MULTI FUNCTION
DIGITAL RELAYS
NP 800 RANGE
APPLICATION GUIDE
ICE - 11, rue Marcel Sembat - 94146 ALFORTVILLE CEDEX - France
PHONE. : +33 1 41 79 76 00 - FAX : +33 1 41 79 76 01 – EMAIL : contact@icelec.com
WEB SITE: www.groupeice.com
Application Guide
NP800 range
Issue : D
File : A0331E1E
Date : 08/2006
This document is the sole property of the ICE. No duplication nor release to third party is allowed without prior authorization
FOREWORD
The aim of this guide is the introduction of the functions and the settings of the relays of
NP800 series as well as examples of application.
The guide of application comprises, for each function available of each relay, following
information:
♦ Description of the function
♦ Parameters of setting
♦ Setting advice.
This guide comes in complement from the other documents from the NP800 series:
♦ "General presentation of the NP800 range", which mainly presents the functions of each
product of the range, its physical characteristics and withstands to the environmental
standards.
♦ "User’s Guide for setting software for the NP800 range ", which describes the available
tool of configuration and its use on PC or in connection with an electric SCADA, as well
as the description of the communication protocols.
♦ "User’s Guides” for each kind of relay, which present the local Man Machine Interface,
available through display and keyboard. These guides are different for the following
relays:
♦ NPI800 and NPID800 relay
♦ NPIH800 and NPIHD800 relay
♦ NPM800 relay
♦ NPU800 relay
♦ NPUH800 relay
♦ "First Handling Guides” for each kind of relay", which present information necessary to
the setting and the operation of the relays, such as their mode of connection and a
sample of recommended tests. These guides are different for the following relays:
♦ NPI800 relay
♦ NPID800 relay
♦ NPIH800 relay
♦ NPIHD800 relay
♦ NPM800 relay
♦ NPU800 relay
♦ NPUH800 relay
The functions of protection and operation described in the following chapters are user
configurable locally or using the setting software.
This document is the sole property of ICE.
No duplication nor release to third party is
allowed without prior authorization
Application Guide
NP800 range
Date : 08/2006
Sheet : 1
Print : 09/03/2007
Issue : d
CONTENTS
1.
GETTING STARTED ________________________________________________________________ 6
1.1
SUMMARY TABLE OF THE AVAILABLE FUNCTIONS ................................................................................... 6
1.2
WARNING ................................................................................................................................................ 7
1.2.1
Operating time ................................................................................................................................ 7
1.2.2
Permanent and short time withstand for the current inputs............................................................ 7
1.2.3
Configuration of the output relays .................................................................................................. 7
1.2.4
NPU-NPUH-NPID, relay secondary nominal voltage configuration (Un)..................................... 7
2. PHASE OVER CURRENT FUNCTION [50] [51]__________________________________________ 8
2.1
DESCRIPTION OF THE FUNCTION ............................................................................................................... 8
2.2
SETTING CHARACTERISTICS ..................................................................................................................... 8
2.3
SETTING ADVISES ..................................................................................................................................... 9
2.3.1
Choice of the time/current characteristic - [51] ............................................................................. 9
2.3.2
Setting example - [50] [51] ........................................................................................................... 10
3. DIRECTIONAL PHASE OVER CURRENT FUNCTION [67]______________________________ 11
3.1
DESCRIPTION OF THE FUNCTION ............................................................................................................. 11
3.1.1
Principle of measurement.............................................................................................................. 12
3.1.2
Operating modes ........................................................................................................................... 13
3.2
SETTING CHARACTERISTICS ................................................................................................................... 13
3.3
SETTING ADVISES ................................................................................................................................... 13
4. EARTH FAULT FUNCTION [50N] [51N]_______________________________________________ 15
4.1
DESCRIPTION OF THE FUNCTION ............................................................................................................. 15
4.2
SETTING CHARACTERISTICS ................................................................................................................... 15
4.3
SETTING ADVISES ................................................................................................................................... 16
4.3.1
Network with isolated neutral ....................................................................................................... 16
4.3.2
Network with impedance earthed neutral ..................................................................................... 16
4.3.3
Network with solidly earthed neutral (or low impedance) ............................................................ 17
4.3.4
Setting example - [50N] [51N] – 3CTs – CBCT 100/1 – CBCT 1500/1 ....................................... 17
5. DIRECTIONAL EARTH FAULT PROTECTION FUNCTION [67N] _______________________ 18
5.1
DESCRIPTION OF THE FUNCTION ............................................................................................................. 18
5.1.1
Operating modes ........................................................................................................................... 19
5.1.2
Inhibition of the function [67N] .................................................................................................... 20
5.2
SETTING CHARACTERISTICS ................................................................................................................... 20
5.3
SETTING ADVISES ................................................................................................................................... 20
6. NEGATIVE PHASE SEQUENCE OVERCURRENT FUNCTION [46] ______________________ 21
6.1
DESCRIPTION OF THE FUNCTION ............................................................................................................. 21
6.2
SETTING CHARACTERISTICS ................................................................................................................... 21
6.3
SETTING EXAMPLE ................................................................................................................................. 22
7. MINIMUM OF CURRENT FUNCTION [37] ____________________________________________ 23
7.1
DESCRIPTION OF THE FUNCTION ............................................................................................................. 23
7.2
SETTING CHARACTERISTICS ................................................................................................................... 23
8. TRIPPING CURVES [46], [51] AND [51N] ______________________________________________ 24
8.1
TIME DELAY WITH DEFINITE TIME CHARACTERISTIC .............................................................................. 24
8.2
DEPENDENT SPECIFIED TIME ACCORDING TO IEC STANDARD ................................................................ 24
8.2.1
Equation ........................................................................................................................................ 24
8.2.2
Choice example for a dependent specified time curve .................................................................. 24
8.2.3
IEC - Inverse Time Curves ............................................................................................................ 27
8.2.4
IEC - Very Inverse Time Curves.................................................................................................... 28
8.2.5
IEC - Extremely Inverse Time Curves ........................................................................................... 29
8.3
DEPENDENT SPECIFIED TIME ACCORDING TO ANSI/IEEE STANDARD .................................................... 30
8.3.1
Equation ........................................................................................................................................ 30
8.3.2
Setting advises............................................................................................................................... 30
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Application Guide
NP800 range
Date : 08/2006
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8.3.3
ANSI/IEEE - Moderately Inverse Time Curves ............................................................................. 31
8.3.4
ANSI/IEEE – Very Inverse Time Curves ....................................................................................... 32
8.3.5
ANSI/IEEE – Extremely Inverse Time Curves............................................................................... 33
8.4
DEFINITE TIME CHARACTERISTIC FOR ELECTROMECHANICAL RELAYS TYPE (RI CURVES) ..................... 34
8.4.1
Equation ........................................................................................................................................ 34
8.4.2
Application .................................................................................................................................... 34
8.4.3
Relatively Inverse Curves.............................................................................................................. 35
8.5
USER PROGRAMMABLE DEPENDENT TIME CURVES ............................................................................... 36
9. DETECTION OF BROKEN CONDUCTOR FUNCTION [46 BC]___________________________ 37
9.1
DESCRIPTION OF THE FUNCTION ............................................................................................................. 37
9.2
SETTING CHARACTERISTICS ................................................................................................................... 37
9.3
SETTING ADVISES ................................................................................................................................... 37
10. OVER-VOLTAGE FUNCTION [59] ___________________________________________________ 38
10.1 DESCRIPTION OF THE FUNCTION ............................................................................................................. 38
10.2 EXAMPLES ............................................................................................................................................. 38
10.3 SETTING CHARACTERISTIC ..................................................................................................................... 39
10.4 SETTING EXAMPLE ................................................................................................................................. 39
11. UNDER VOLTAGE FUNCTION [27] __________________________________________________ 40
11.1 DESCRIPTION OF THE FUNCTION ............................................................................................................. 40
11.2 SETTING CHARACTERISTICS ................................................................................................................... 40
11.3 SETTING EXAMPLE ................................................................................................................................. 41
12. POSITIVE SEQUENCE VOLTAGE DROPS FUNCTION [27P] ____________________________ 42
12.1 DESCRIPTION OF THE FUNCTION ............................................................................................................. 42
12.2 CARACTÉRISTIQUES DE RÉGLAGES......................................................................................................... 42
12.3 SETTING EXAMPLE ................................................................................................................................. 43
13. ZERO-SEQUENCE OVER-VOLTAGE FUNCTION [59N] ________________________________ 44
13.1 DESCRIPTION OF THE FUNCTION ............................................................................................................. 44
13.2 SETTING CHARACTERISTICS ................................................................................................................... 44
13.3 > SETTING EXAMPLE .............................................................................................................................. 44
13.3.1
Setting example in measured mode ............................................................................................... 45
13.3.2
Setting example in calculated mode .............................................................................................. 45
14. TRIPPING CURVES [27], [27P], [59] AND [59N] ________________________________________ 46
14.1 DEFINITE TIME DELAY [27], [59] AND [59N].......................................................................................... 46
14.2 DEPENDENT SPECIFIED TIME ACCORDING TO IEC STANDARDS [27] ....................................................... 46
14.2.1
Equation ........................................................................................................................................ 46
14.2.2
IEC - Inverse Time Curves ............................................................................................................ 47
14.2.3
IEC - Very Inverse Time Curves.................................................................................................... 48
14.2.4
IEC - Extremely Inverse Curves.................................................................................................... 49
14.3 DEPENDENT SPECIFIED TIME ACCORDING TO ANSI/IEEE STANDARDS [27]........................................... 50
14.3.1
Equation ........................................................................................................................................ 50
14.3.2
ANSI/IEEE - Moderately Inverse Time Curves ............................................................................. 51
14.3.3
ANSI/IEEE - Very Inverse Time Curves........................................................................................ 52
14.3.4
ANSI/IEEE - Extremely Inverse Time Curves ............................................................................... 53
15. UNDER AND OVER FREQUENCY FUNCTION [81] ____________________________________ 54
15.1 DESCRIPTION OF THE FUNCTION ............................................................................................................. 54
15.2 SETTING CHARACTERISTICS ................................................................................................................... 54
16. THERMAL IMAGE CABLE AND TRANSFORMER FUNCTION [49]______________________ 55
16.1 CABLE THERMAL IMAGE FUNCTION [49]................................................................................................ 55
16.1.1
Description of the function............................................................................................................ 55
16.1.2
Setting characteristics ................................................................................................................... 56
16.1.3
Setting example ............................................................................................................................. 56
16.2 TRANSFORMER THERMAL IMAGE FUNCTION [49] .................................................................................. 57
16.2.1
Description of the function............................................................................................................ 57
16.2.2
Value of the Time-constant Ct....................................................................................................... 57
16.2.3
Setting characteristics ................................................................................................................... 58
16.2.4
Setting example ............................................................................................................................. 58
16.3 THERMAL HEATING CURVES (CABLE AND TRANSFORMER)..................................................................... 59
16.3.1
Characteristic of the thermal image.............................................................................................. 59
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NP800 range
Date : 08/2006
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Issue : d
16.3.2
Thermal cooling curves (cable and transformer).......................................................................... 60
16.4 HOT RESTARTING INHIBITION - CABLE AND TRANSFORMER .................................................................. 61
16.4.1
Description of the function............................................................................................................ 61
16.5 SETTING CHARACTERISTICS ................................................................................................................... 61
17. ON LOAD RECLOSING FUNCTION __________________________________________________ 62
17.1 DESCRIPTION OF THE FUNCTION ............................................................................................................. 62
17.2 SETTING CHARACTERISTICS ................................................................................................................... 62
18. MOTOR THERMAL IMAGE FUNCTIONS [49]_________________________________________ 63
18.1 DESCRIPTION OF THE THERMAL IMAGE FUNCTION ................................................................................. 63
18.1.1
General.......................................................................................................................................... 63
18.1.2
Time-constant................................................................................................................................ 63
18.2 DESCRIPTION OF THE HOT MOTOR RESTARTING INHIBITION FUNCTION .................................................. 64
18.3 SETTING CHARACTERISTICS ................................................................................................................... 64
18.4 SETTING ADVISES ................................................................................................................................... 65
18.5 THERMAL HEATING CURVES (MOTOR).................................................................................................... 67
18.6 THERMAL COOLING CURVE (MOTOR) ..................................................................................................... 68
19. TOO LONG START [48] AND LOCKED ROTOR FUNCTIONS [51LR] ____________________ 69
19.1 DESCRIPTION OF THE FUNCTIONS ........................................................................................................... 69
19.2 SETTING CHARACTERISTICS ................................................................................................................... 69
19.3 SETTING ADVISES ................................................................................................................................... 69
20. NUMBER OF STARTS RESTRICTION FUNCTION [66] _________________________________ 71
20.1 DESCRIPTION OF THE FUNCTION ............................................................................................................. 71
20.2 SETTING CHARACTERISTICS ................................................................................................................... 71
20.3 SETTING ADVISES ................................................................................................................................... 71
21. PHASE TO PHASE [50] AND EARTH-FAULT [51N] SHORT-CIRCUIT ____________________ 72
21.1 DESCRIPTION OF THE FUNCTION ............................................................................................................. 72
21.2 SETTING CHARACTERISTICS ................................................................................................................... 72
21.3 SETTING ADVISES ................................................................................................................................... 73
21.4 FUNCTION [50]....................................................................................................................................... 73
21.4.1
Function [51N] ............................................................................................................................. 73
22. MINIMUM OF LOAD - UNPRIMING [37]______________________________________________ 75
22.1 DESCRIPTION OF THE FUNCTION ............................................................................................................. 75
22.2 SETTING CHARACTERISTICS ................................................................................................................... 75
22.3 SETTING ADVISES ................................................................................................................................... 75
23. UNBALANCE, REVERSAL AND LOSS OF PHASE [46]__________________________________ 76
23.1 DESCRIPTION OF THE FUNCTION ............................................................................................................. 76
23.2 SETTING CHARACTERISTICS ................................................................................................................... 76
23.3 SETTING ADVISES ................................................................................................................................... 76
23.4 NEGATIVE SEQUENCE CURRENT TRIP CURVES ........................................................................................ 77
24. LOAD-SHEDDING WITH EXTERNAL INPUT AND HIGH SPEED RESTARTING __________ 78
24.1 DESCRIPTION OF THE FUNCTION ............................................................................................................. 78
24.2 SETTING CHARACTERISTICS ................................................................................................................... 78
25. INPUTS – OUTPUTS RELAYS CONFIGURATION & LED INDICATORS__________________ 79
25.1 DIGITAL INPUTS ..................................................................................................................................... 79
25.2 OUTPUTS RELAYS AND FUNCTION [86]................................................................................................... 79
25.3 LED INDICATORS................................................................................................................................... 79
26. CIRCUIT-BREAKER MAINTENANCE________________________________________________ 81
26.1 TRIP CIRCUIT SUPERVISION OF THE CIRCUIT-BREAKER [74TC] ............................................................. 81
26.1.1
Calculation of the additional resistor ........................................................................................... 84
26.1.2
Operating mode of the digital input .............................................................................................. 85
26.1.3
Wiring of the trip circuit................................................................................................................ 85
26.1.4
Characteristics of the function [74TC] ......................................................................................... 85
26.2 CIRCUIT-BREAKER FAILURE [50BF] ...................................................................................................... 86
27. LOGICAL SELECTIVITY FUNCTION ________________________________________________ 88
27.1 DESCRIPTION OF THE FUNCTION ............................................................................................................. 88
27.2 OPERATING MODE OF THE LOGICAL SELECTIVITY INPUT ........................................................................ 90
27.3 SETTING CHARACTERISTICS ................................................................................................................... 90
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NP800 range
Date : 08/2006
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Issue : d
28. REMOTE CONTROL FUNCTION ____________________________________________________ 91
28.1 TRIP BY REMOTE CONTROL .................................................................................................................... 91
28.2 CLOSING BY REMOTE CONTROL ............................................................................................................. 91
28.3 LOAD-SHEDDING BY PRIORITY LEVEL .................................................................................................... 91
28.4 RECONNECTION ..................................................................................................................................... 92
29. PROGRAMMABLE GENERIC FUNCTIONS ___________________________________________ 93
30. RELAY PARAMETERS _____________________________________________________________ 94
30.1 SETTING GROUPS 1 AND 2 ...................................................................................................................... 94
30.2 PRIORITIES MANAGEMENT ..................................................................................................................... 94
31. EVENTS___________________________________________________________________________ 95
31.1 STORAGE/ACKNOWLEDGEMENT ............................................................................................................. 95
31.2 CONTENTS OF AN INTERNAL EVENT ....................................................................................................... 95
31.3 EVENTS MODES MANAGEMENT .............................................................................................................. 95
31.4 TIME-STAMPING ..................................................................................................................................... 95
31.5 CHARACTERISTICS ................................................................................................................................. 95
32. DISTURBANCE RECORDING _______________________________________________________ 96
33. OPERATING PARAMETERS ________________________________________________________ 97
34. COMMUNICATION ________________________________________________________________ 98
This document is the sole property of ICE.
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Application Guide
NP800 range
Date : 08/2006
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Issue : d
1.
Getting started
1.1
Summary table of the available functions
Function
Phase Over-current Function [50] [51]
NPI
800
NPID
800
X
X
Directional phase fault protection Function [67]
NPIH
800
NPIHD
800
X
X
NPU
800
NPUH
800
NPM
800
X
Earth fault Function [50N] [51N]
X
Directional earth fault protection Function [67N]
X
X
Negative Phase Sequence Overcurrent Function [46]
X
X
X
Consult
us
Minimum of current Function [37]
Detection of Broken conductor Function [46 BC]
X
X
Over-voltage Function [59]
X
Zero-sequence Over-Voltage Function [59N]
X
Under-voltage Function [27]
X
Positive Sequence Voltage Drops Function [27P]
X
Minimum and Over Frequency Function [81]
X
Cable thermal image Function [49]
X
X
Transformer Thermal image Function [49]
X
X
Hot restarting Inhibition Function [49]
X
X
On Load Reclosing Function
X
X
X
Motor Thermal image Functions [49]
X
Too Long Start [48] and Locked Rotor Functions [51LR]
X
Starts Limiter Function [66]
X
Phase to Phase Short-Circuit [50] and Earth-fault [51N]
X
Minimum of Load - Unpriming [37]
X
Unbalance, Rotation and Loss of Phase [46]
X
Load-shedding with External Input and High Speed
Restarting
X
Circuit-breaker Failure [50BF]
X
X
X
X
Trip Circuit Supervision of the circuit-breaker [74TC]
X
X
X
X
X
X
X
Output contact maintained - Function [86]
X
X
X
X
X
X
X
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Application Guide
NP800 range
X
Date : 08/2006
Sheet : 6
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1.2
Warning
All the technical characteristics described in this guide indicate the specificities of the NP800
range. The following warnings must be taken into account, in order to ensure their correct
operation.
1.2.1 Operating time
This guide refers to the curves with dependent specified time in accordance with the IEC
60255-4 and ANSI-IEEE standards. The setting of the relays authorizes the choice of points
of operation on these curves, by setting the desired value (modulo in step of setting).
The internal response time of the protection (measurement and chain of trip) is 20 ms.
To obtain the real tripping time of the protection, an additional time of 20 ms must thus be
added.
In order to keep the best accuracy, Standard curves or formulas should be used, as curves
shown in this guide may be not precise enough.
1.2.2 Permanent and short time withstand for the current inputs
Phase Inputs: if the phase threshold is higher than 3 x In, it should be checked that the value
of the time delay or the choice of the curve is not prejudicial to the thermal withstand of the
phase inputs: 3 x In permanent, 24 x In 20s, 100 x In 1s.
Earth-fault Input: if the earth threshold is higher than 2 x In0, it should be checked that the
value of the time delay or the choice of the curve is not prejudicial to the thermal withstand of
the earth-fault input: 2 x permanent In0, 10 x In0 20s, 40 x In 1s.
1.2.3 Configuration of the output relays
The protective functions described hereafter do not carry out automatically the configuration
of trip output relay.
After the activation and the setting of these functions, it will be necessary to proceed to the
configuration of the protection by the matrix assignment of the output relays by taking
account of their breaking capacity.
1.2.4 NPU-NPUH-NPID, relay secondary nominal voltage configuration (Un)
The configuration of the nominal voltage value of the relay (Un) must be carried out
according to the secondary wiring connection of the voltage transformers (VTs) and their
secondary rated voltage value. (Ex: 100/√3, 110/√3, 100, 110 …)
Configuration according to the characteristics describe below:
Parameter range for the nominal value of the
measurement voltage (Un)
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Application Guide
NP800 range
33 V up to 120 V
(step of 0.1 V)
Date : 08/2006
Sheet : 7
Print : 09/03/2007
Issue : d
2.
Phase Over Current Function [50] [51]
2.1
Description of the function
The phase over-current functions ensure the elimination of overload or short-circuit, phase to
phase or phase to earth faults.
Three thresholds are available:
♦ one instantaneous or definite time "very high" threshold [50]
♦ one "high" threshold [51-1] with 8 modes of time delay: definite time, IEC or ANSI
dependent specified time, or configurable (factory set, please consult us)
♦ one "low" threshold [51-2] with 8 modes of time delay: definite time, IEC or ANSI
dependent specified time, or configurable (factory set, please consult us).
2.2
Setting characteristics
CHARACTERISTICS
Values
Accuracy
Resetting Percentage
94 %
± 1.5 %
Response time of the instantaneous outputs
60 ms
Typical for I ≥ 2
Is
Overshoot
< 35 ms
Time delays and threshold of 51-1 -- 51-2 functions
Definite time delay - t (I >) (I > >)
Inverse time curve IEC 60255-4 - t (I >) t (I > >)
Very inverse time curve IEC 60255-4 - t (I >) t (I > >)
Extremely inverse time curve IEC 60255-4 - t (I >) t (I
> >)
Moderately inverse time curve ANSI/IEEE - t (I >) t (I
> >)
Very inverse time curve ANSI/IEEE - t (I >) t (I > >)
Extremely inverse time curve ANSI/IEEE - t (I >) t (I
> >)
Relatively Inverse time curve - t (I >) t (I > >)
High-set I> > - [ 51-2 ]
Low-set I> - [ 51-1 ]
Time delay and threshold of the 50 function
Definite time delay - t (I > > >)
Very high-set - I> > >
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Application Guide
NP800 range
Setting
40 ms up to 300 s
In step of: see *
T++: 30 ms up to 3 s
in step of 0.01s
T++: 30 ms up to 3 s
in step of 0.01s
T++: 30 ms up to 3 s
in step of 0.01s
T++: 30 ms up to 3 s
in step of 0.01s
T++: 30 ms up to 3 s
in step of 0.01s
T++: 30 ms up to 3 s
in step of 0.01s
100 ms up to 20 s in
step of 0.1 s
0.3 up to 24.0 In
in step of 0.1 In
0.3 up to 24.0 In
in step of 0.1 In
Accuracy
± 2 % or ± 20 ms
Setting
40 ms up to 300 s
In step of: see *
0.3 up to 24.0 In
in step of 0.1 In
Accuracy
± 2 % or ± 20 ms
Class 5
Class 5
Class 5
Class 5
Class 5
Class 5
Class 5
±5%
±5%
±5%
Date : 08/2006
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Print : 09/03/2007
Issue : d
*: from 0.04 up to 9.99 s in step of 0.01 s, 10.0 s up to 29.9 s in step of 0.1 s, 30 up to 300 s
in step of 1s
The accurate characteristics of the curves with dependent specified time are defined in the
chapter "Tripping curves [46], [51] and [51N]".
2.3
2.3.1
Setting advises
Choice of the time/current characteristic - [51]
Overcurrent protective relay which constitutes the basic protection of an electrical supply
network must be both sensitive and fast in order to minimize the stress on the equipment
during the fault period (electro dynamical strains and heating effects).
It also must be selective, i.e. able to clear only the faulty element and thus to preserve the
electric supply of the healthy elements.
This is why an over-current protective relay is mainly specified by its time/current
characteristic:
♦ Definite time: the response time is independent of the current.
♦ Dependent time: the response time depends on the current, according to IEC 602554 and ANSI-IEEE standards:
♦ inverse - IEC 60255-4 / moderately inverse - ANSI-IEEE
♦ very inverse - IEC 60255-4 / very inverse - ANSI-IEEE
♦ extremely inverse - IEC 60255-4 / extremely inverse - ANSI-IEEE
♦ Dependent time, according to Relatively Inverse curves "RI" (electromechanical).
No technical criterion exists for a systematic choice of one of these eight characteristics.
However there is an historical tendency to the use of protective relay with definite time
characteristic in Continental Europe and with dependent specified time characteristic in the
Anglo-Saxon countries. The ANSI-IEEE standard is followed in a prevalent way in the United
States and in the South Pacific countries.
Nowadays, digital multi-function and multi-curves protective relays attenuate these
differences by offering choice between different curves.
Dependent time characteristics are advised when:
♦ Significant and short time overloads may occur during operation
♦ High magnetizing or inrush currents may appear during several tenths of seconds
♦ The operation of the protective relays must be coordinated with a great number of
fuses.
On the other hand, the use of definite time relays is preferable when short-circuit currents are
extremely high, or when they are likely to vary very widely at a given point of the network.
This may happen for instance when a network includes small generators with rapidly
decreasing short-circuit currents.
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Application Guide
NP800 range
Date : 08/2006
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Issue : d
2.3.2 Setting example - [50] [51]
According to the value determined by a co-ordination study or a setting table study, the
thresholds [50] and [51] set on the protection must be adapted to the rated value of the
current transformers (CTs) and possibly corrected according to the steps of the setting
range. Let us consider as an example the following data:
♦ CT = 250/5 A
♦ In Relay = 5 A
♦ Trip value calculated in the event of short-circuit = 2470 A with an instantaneous
response time.
♦ Trip value calculated in the event of overload = 380 A with a definite time
characteristic and a time delay of 4.5 s.
Calculation of the thresholds and parameters to be set on the protection:
♦ For detection of short-circuits, the function [50] will be set as follows:
I> > > = 2470/250=9.88,
corrected by the setting step: 9.9 x In CT.
An output relay will be parameterized with "instantaneous" function.
♦ For overload, the function [51-1] will be set as follows:
I> = 380/250=1.52,
corrected by the setting step: 1.5 x In CT.
The operating feature will be a definite time characteristic and the time delay set at
4.5 s.
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NP800 range
Date : 08/2006
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3.
Directional Phase Over Current Function [67]
3.1
Description of the function
This type of protection is used to determine and clear the faulty element whenever either
several sources feed the same bus bar, or several cables in parallel connect two bus bars.
Example of application #1:
In case of a fault located in "A" on the
network, the currents measured by the
incomer’s protection "TR" and "G" are of
identical amplitude, but in opposite
directions.
A directional criterion [67] allows clearing
the generator "G" and letting the "TR"
transformer feed the network.
TR
G
A
I
[67]
[50]
I
[50]
[67] ↑: the arrow indicates the orientation
of the tripping zone of the relay.
[67]
[50]
[50]
[67]
[67]
Example of application #2:
In case of a fault located in "B" on the
network, the currents measured by the
downstream bus bar incomer’s protection,
fed by two cables in parallel, are of
identical amplitude, but in opposite
directions.
A directional criterion [67], allowing
insulation the faulty cable, must be
selected for these incomers protections. In
this case the fault will be cleared initially
by the [67] protection then, thanks to a
time selectivity, by the upstream
protection, thus allowing the supply of the
network by the operational cable.
TR
G
[67]
[50]
[67]
[50]
[50]
[50]
B
I
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[67]
I
[67] ↑: the arrow indicates the orientation
of the tripping zone of the relay.
[67]
Application Guide
NP800 range
Date : 08/2006
Sheet : 11
Print : 09/03/2007
Issue : d
The directional function does not require time selectivity with the former protections of the
network. However its time delay must be sufficient to eliminate the risks of trip due to the
transient’s phenomena. With sensitive settings, dependent specified time characteristic
should be chosen.
To fit with these applications, the directional phase function [67] of the NPID800 relays is
linked to:
♦ The phase over-current functions, [50] [51-1] [51-2]
♦ A phase comparator intended to determine the direction of the fault current.
The detection of the fault is conditioned by 2 criteria:
♦ The threshold of one of the phase over-current functions, [50] [51-1] [51-2] assigned
of a directional criterion, is overreached during a time greater than the time set or
according to the chosen curve
♦ The fault current is located in the tripping zone.
The phase comparator allows, using measurement of phase shift between current and
associated phase to phase voltage: I1/U32 and I3/U21, to determine the direction of the fault
current. Let us note that the voltage of the fault phase is weak in the case of close faults and
is not used for measurement.
3.1.1 Principle of measurement
From the reference voltage U32 (compared to current I1), the polarization voltage VP
determines a zone of non trip. The vector representative of this voltage is located at the
centre of a 180°zone delimiting the zones of trip a nd non trip.
The position of this zone can be changed by modifying the value of the α characteristic
angle.
+ 30°
V1
line=-60°
I1 (short-circuit
line side "B")
U32
α
=30°
Vp
I1 (short-circuit
substation side)
- 150°
Non trip zone
According to the application example #2, if θline (argument of the line) corresponds to a selfinductive line, with a current I1 lag of approximately 60°, the α characteristic angle will be set
to +30° (see the SETTING ADVISE table). In this cas e the relay will be authorized for tripping
with currents shift from +30° up to –150°.
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NP800 range
Date : 08/2006
Sheet : 12
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Issue : d
Under normal operation, the I1 current will be located in the non tripping zone, lag to V1.
In case of short-circuit, the current will be located in the tripping zone for a "B" side line shortcircuit, therefore in opposition of phase with Vp, and in the zone of non tripping for a shortcircuit substation side. The principle is similar for I3 and V3 compared to U21.
3.1.2 Operating modes
If the polarization voltage is weak, the angle of the directional function cannot be accurately
measured. In this case, the operating mode of protection depends on the chosen operation
mode (common choice for the functions [67] and [67N]):
Permission Mode
When voltage is lower than the operating level of polarization, the protection does not take
into account the directional criterion [67] and trips by the over-current [50] [51-1] [51-2]
functions assigned with this criterion.
Blocking Mode
In the event of voltage lower than the operating level of polarization, the trip by the overcurrent [50] [51-1] [51-2] functions assigned with a directional criterion [67] is forbidden.
3.2
Setting characteristics
CHARACTERISTICS
Values
Accuracy
Measurement angle Vp/I1 and Vp/I3
-180° up to +180°
± 5°
α angle setting
-180° up to +180°
in step of 1°
3% of Un*
± 5°
Operating level
± 1%
* See chapter 3.2.1: NPU-NPUH-NPID, relay secondary nominal voltage configuration (Un)
3.3
Setting advises
As described in the two previous paragraphs, the optimum setting of the α characteristic
angle must be such that the supervised fault current is in opposition of phase with the Vp
polarization voltage.
In this case, the fault current is in the centre of the trip zone and gives the maximum
sensitivity.
Three parameters allow determining the α angle:
♦ direction of the tripping zone wished for protection
♦ argument θ (value without sign) corresponding to the impedance of the line
(generally self-inductive)
♦ type of fault: three-phase, two-phase.
The last parameter is generally not taken into account because its influence is very poor for
the setting of the α angle.
The optimal α angle is provided by the relation:
♦ "line side" trip direction: α = 90 ° - θ
♦ "substation side" trip direction: α = - (90 ° + θ).
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NP800 range
Date : 08/2006
Sheet : 13
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Issue : d
Argument θ corresponding to the selfinductive impedance of the line
θ = 75 °
Setting of α according to the supervised direction
"line side" direction
"substation side" direction
+ 15 °
- 165 °
θ = 60 °
+ 30 °
- 150 °
θ = 45 °
+ 45 °
- 135 °
θ = 30 °
+ 60 °
- 120 °
The only conditions to take into account are those which exist at the time of fault. Thus, if we
consider a line AB, of a ring main system, at the time when the fault appears between A and
B, the two ends must be considered as a source and the direction of the currents is as
indicated below. The two currents at the two ends of the line are nearly in opposition of
phase and feed the fault.
A
B
In this example, at each end A and B a directional relay is installed, intended to trip his own
circuit-breaker. In the case of a fault located between A and B, the two directional protections
are directed "line side". They will operate both for a fault which will be located downstream
for each one of them, because when fault occurs, the A and B ends behave like sources. For
a fault located on the left side of A, the directional protection of A detects it as upstream fault
and the directional protection of B as downstream one. This situation is reverse for a fault on
the right side of B.
For some application of bus bars protection, in substation A, for instance, directional relays
can be installed on the three lines which converge towards as A. A bus bar fault is detected if
the three directional detects the fault in the "substation side" direction. In this case, the
tripping zone of the directional relays must be set "substation side".
The α angle, such as it is defined in the above "Settings characteristics” paragraph is used to
adjust monitoring towards "line side" or "substation side” and this independently of the
direction of the flow of energy in normal circumstances. The orientation of directional is
defined according to the conditions of currents and existing voltages at the fault time.
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NP800 range
Date : 08/2006
Sheet : 14
Print : 09/03/2007
Issue : d
4.
Earth Fault Function [50N] [51N]
4.1
Description of the function
The earth fault function ensures the clearance of the faults between phase and earth.
Two thresholds are available:
♦ one "high" threshold [50N] instantaneous or with a definite time characteristic
♦ one "low" threshold [51N] with 8 modes of time delay: definite type, curves with
dependent specified time IEC or ANSI, or configurable (factory set, please consult us)
4.2
Setting characteristics
CHARACTERISTICS
Values
Accuracy
Resetting Percentage
94 %
± 1.5 %
Response time of the instantaneous outputs
60 ms
Typical for I ≥ 2 Is
Overshoot
< 35 ms
Time delays and threshold of the function 51N
Definite time delay - t (Io >)
Setting
40 ms up to 300 s
In step of: see *
Inverse, very inverse, extremely inverse, time curves T++: 30 ms up to
IEC 60255-4 - t (Io >)
3
s
in step of 0.01 s
Moderately inverse, very inverse, extremely inverse, T++: 30 ms up to
time curves ANSI/IEEE - t (Io >)
3
s
in step of 0.01 s
Relatively Inverse time curve - t (Io >)
100 ms up to 20 s
in step of 0.1 s
Low-set - Io > CT connection
0.03 up to 2.40 In
in step of 0.01 In
Low-set - Io > ICE Ring CT** connection (prim.)
0.6 up to 48 A
in step of 0.1 A
Accuracy
± 2 % or ± 20 ms
Time delay and threshold of the function 50N
Definite time delay - t (Io >>)
Accuracy
± 2 % or ± 20 ms
High-set - Io > > CT connection
High-set - Io > > ICE Ring CT** connection (prim.)
Setting
40 ms up to 300 s
In step of: see *
0.03 up to 2.40 In
in step of 0.01 In
0.6 up to 48 A
in step of 0.1 A
Class 5
Class 5
Class 5
±5%
±5%
±5%
±5%
*: from 0.04 up to 9.99 s in step of 0.01 s, 10.0 s up to 29.9 s in step of 0.1 s, 30 up to 300 s
in step of 1s
** CBCT 100/1 and use of BA800 for CBCT 1500/1
The accurate characteristics of the curves with dependent specified time are defined in the
chapter "Tripping curves [46], [51] and [51N]".
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NP800 range
Date : 08/2006
Sheet : 15
Print : 09/03/2007
Issue : d
4.3
Setting advises
An industrial electrical network may have three distinct types of neutral systems. The three
possibilities will be described below: isolated neutral (or un-earthed), impedance earthed
neutral, solidly earthed neutral (or low impedance).
4.3.1 Network with isolated neutral
In isolated neutral networks, the earth fault current amplitudes are limited to the total
capacitive current of the different elements of the installation.
An insulation monitoring device must be used to allow, after detection of the fault, its
clearance as quickly as possible and thus to avoid the risk of a second fault appearing before
this clearance.
This function [59N] is provided by a zero sequence voltage NPUH800 relay (neutral
displacement) (see the paragraph dedicated to this function).
In some cases, an automatic selective clearance of a fault may be obtained as soon as it
appears with a phase to earth sensitive over-current relays [50N] or [51N] fed by a ring CT
including the three phases of the cables. These functions are available with NPI800,
NPID800 and NPIH800 relays.
The setting of these relays must be fixed at approximately 1 time ½ the capacitive current of
the protected feeder. When a fault affects a nearby feeder, the capacitive current of the two
healthy phases "goes up" the remaining healthy feeder to feed the fault, with the risk of a
spurious trip of the protection in case threshold is too weak.
In addition, in order to obtain enough sensitivity in the event of a resistant fault, it is
necessary that the total capacitive current of the network be higher than 5 times that of the
longest feeder, i.e. equal to approximately 3 times the highest setting of the relays of the
installation.
If this condition cannot be satisfied due to the presence of a too long feeder, it is possible to
use a directional earth fault protection relay [67N]. These functions are available with
NPID800 and NPIHD800 relays (see the paragraph dedicated to this function).
Please note that this type of protection can operate satisfactorily only if the number of
operating feeders (thus the capacity phase - earth) remains relatively constant. A selective
detection is hardly obtained when the electrical supply network comprises loops.
4.3.2 Network with impedance earthed neutral
For these networks, the earth-fault current is limited to a given value which can be
comprised, approximately, between ten and a thousand amps. The different feeders must be
fitted with an earth-fault protection [50N] or [51N], fed by a ring CT or by a residual
connection of the 3 line CTs. In this last case, the threshold should not be set below 6% of In
CT.
In the event of phase to phase short-circuit, the current transformers may saturate in a nonsymmetrical manner, and this can cause spurious tripping of a protection set with a too low
threshold. If a protection fed by a ring CT is used, the threshold could be set at 1 time ½ the
capacitive earth-fault current of the feeder.
The [50N] or [51N] functions are available with NPI800, NPID800 and NPIH800 relays.
When several neutral points are earthed simultaneously, it is necessary to use directional
earth fault relays type [67N] in order to disconnect selectively one of the sources of zerosequence current at fault time (see the paragraph dedicated to this function).
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NP800 range
Date : 08/2006
Sheet : 16
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Issue : d
4.3.3 Network with solidly earthed neutral (or low impedance)
The network is generally earthed on the neutral of a delta-star transformer incomer.
When this neutral is not available, the zero sequence generators consist of a coil with zigzag
coupling or a star-delta transformer connected on the main bus-bars. Thus the earth fault
current is limited only by the zero sequence reactance of the transformer or by the coil and
its maximum value will be of close of the three-phase short-circuits.
It is thus possible to use with a good sensitivity NPI800 or NPID800 protections fed by a
residual connection of the 3 line CTs.
4.3.4 Setting example - [50N] [51N] – 3CTs – CBCT 100/1 – CBCT 1500/1
According to the value determined by a co-ordination study or a setting table study, the
thresholds [50N] and [51N] set on the protection must be adapted to the rated current of the
current transformers and possibly corrected according to the step of the setting range.
Let us consider as an example the three following cases:
Measure of the zero sequence current using a residual connection of 3 line CTs:
♦ CT = 250/5 A
♦ In Relays = 5 A (nominal current of earth input = nominal current of phase input)
♦ Value of trip in the event of earth fault = 16 A with a definite time delay of 0.5 s.
Calculation of the thresholds and parameters to be set on protection:
♦ For the detection of the earth faults, the function [51N] will be set as follows:
Io > = 16/250=0.064.
The operating feature will be chosen with a definite time characteristic and the time
delay set at 0.5 s.
Measure of the zero sequence current using CBCT 100/1:
♦ ICE Ring CT TF 80-1
♦ In Relay = 0.2 A (earth nominal current for ring CT)
♦ Value of trip in the event of earth fault = 16 A with a definite time delay of 0.5 s.
Calculation of the thresholds and parameters to be set on protection:
♦ For the detection of the earth faults, the function [51N] will be set as follows:
Io > = 16/20=0.8.
The operating feature will be chosen with a definite time characteristic and the time
delay set at 0.5 s,
Note: 20 = coefficient taking account of the ring CT ratio, 100/1, and the nominal current of
the earth input, 0.2 A.
Measure of the zero sequence current using CBCT 1500/1:
♦ CEE Ring CT TF 80-15 and BA800
♦ In Relay = 0.2 A (earth nominal current for ring CT)
♦ Value of trip in the event of earth fault = 16 A with a definite time delay of 0.5 s.
Calculation of the thresholds and parameters to be set on protection:
♦ For the detection of the earth faults, the function [51N] will be set as follows:
Io > = 16/20=0.8.
The operating feature will be chosen with a definite time characteristic and the time
delay set at 0.5 s,
Note: 20 = coefficient taking account of the ring CT ratio, 1500/1, the BA800 ratio and the
nominal current of the earth input, 0.2 A.
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Application Guide
NP800 range
Date : 08/2006
Sheet : 17
Print : 09/03/2007
Issue : d
5.
Directional Earth Fault Protection Function [67N]
5.1
Description of the function
This type of protection is used in two main applications:
♦ As a complement of directional phase protection, to determine and disconnect the
faulty element whenever several sources feed the same bus bar
♦ On radial feeders in strongly capacitive network, if neutral is isolated or impedance
earthed, in order to obtain a sensible earth fault protection without risk of spurious trip
due to the zero sequence capacities.
Application example #1:
In case of fault located in "A" on the
network, the currents measured by the
incomer protections "TR" and "G" are of
identical amplitude, but in opposite
directions.
A directional criterion [67N] is used to
disconnect the generator "G" and to let the
"TR" transformer feed the network.
TR
G
A
I
I
[67N]
[67N]
[67N] ↑: the arrow indicates the orientation
of the tripping zone of the relay.
[50]
[50]
[50]
[50]
Application example #2:
TR
3V0
Z
Io
Vr=V1+V2+V3
Io
Vr
Vr
Vr
[67N]
[67N]
[67N]
Io
Io
In case of a fault located in “B” on the
network, the zero sequence current of the
faulty feeder is equal to the sum of the
currents going through the impedance of
the neutral earthing and due to the zero
sequence capacities of the healthy phases
for the other feeders.
The fault current measured by a healthy
feeder increases proportionally to its zero
sequence capacity and the value of the
earth impedance.
To obtain a sensitive earth fault protection,
a directional criterion allows to disconnect
only the faulty feeder and to let the healthy
feeders feed the network.
B
[67N] ↑: the arrow indicates the orientation
of the tripping zone of the relay.
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NP800 range
Date : 08/2006
Sheet : 18
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Issue : d
According to the application and the type of relay, the zero sequence voltage Vo is calculated
from the measurement of the phase to neutral voltages V1, V2, V3 or from the residual
voltage Vr measured with three open delta voltage transformers.
Note: The phase to earth voltage Vr is equal to three times the zero sequence voltage Vo.
In addition, an operating threshold allows to be freed from the residual voltage due to the
natural unbalance of the healthy network and to the phase shifts introduced by the VT.
With the zero sequence voltage Vo as a reference, the polarization voltage VP determines a
non tripping zone. The vector representative of this voltage is located at the centre of a
180°zone delimiting the zones of trip and non trip.
The position of this zone can be modified according to the setting of the α characteristic
angle.
+ 135°
Io (healthy feeder)
Vp
α
( = + 45 ° )
V0
Io (faulty feeder,
line side)
- 45°
Non tripping zone
According to the application example #1, network with isolated neutral, if the θo argument of
the characteristic angle is 45°, value correspondin g to an approximately 90° phase lead of Io
current referring to zero sequence voltage, the α characteristic angle will be set to 45° (see
the Setting Advises table). In this case the relay will be authorized for tripping with earth fault
currents shift from +135° up to – 45°.
5.1.1 Operating modes
If the polarization voltage is weak, the angle of the directional function cannot be accurately
measured. In this case, the operating mode of protection depends on the chosen operation
mode (common choice for the functions [67] and [67N]):
Permission Mode
When voltage is lower than the operating level of polarization, the protection does not take
into account of the directional criterion [67N] and trips by the earth fault [50N] [51N] functions
assigned of this criterion.
Blocking Mode
In the event of voltage lower than the operating level of polarization, the trip by the earth fault
[50N] [51N] functions assigned of a directional criterion [67N] is forbidden.
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NP800 range
Date : 08/2006
Sheet : 19
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Issue : d
5.1.2 Inhibition of the function [67N]
The directional function may be temporarily inhibited by a digital input or by the digital
communication.
5.2
Setting characteristics
CHARACTERISTICS
Values
Accuracy
Measurement angle Vp/Io angle
-180°à +180°
± 5°
Operating level of Vo
3 % up to 20 % Un*
in step of 1 %
-180° up to +180°
in step of 1°
± 5 % or 1 V
Angle α setting
± 5°
* See chapter 3.2.1: NPU-NPUH-NPID, relay secondary nominal voltage configuration (Un)
5.3
Setting advises
As for the phase directional function, in order to obtain the maximum sensitivity, the setting of
the characteristic angle α must be such that the zero-sequence current due to an earth fault
is as much as possible in opposition of phase with the voltage of polarization Vp.
Two essential parameters are useful to determine the α angle:
♦ direction of the tripping zone wished for protection
♦ θo argument according to the type of neutral system (isolated, impedance earthed or
solidly earthed neutral) and of the capacitive current of the network.
The optimal α angle can be chosen as follows:
♦ "line side" trip direction: α = θo
♦ "substation side" trip direction: α = θo ± 180 °.
The following table is obtained:
Argument θo of the
characteristic angle
Neutral system
Capacitive network with isolated
neutral or neutral connected to the earth
through a high impedance
Network with neutral connected to the
earth through resistance or impedance
Network with solidly earthed neutral
(or low impedance)
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allowed without prior authorization
+ 45 °
Setting of α according to the
supervised direction
"line side"
"substation
direction
side" direction
+ 45 °
- 135 °
+10 °
+10 °
- 170 °
- 20 °
- 20 °
160 °
Application Guide
NP800 range
Date : 08/2006
Sheet : 20
Print : 09/03/2007
Issue : d
6.
Negative Phase Sequence Overcurrent Function [46]
6.1
Description of the function
Any unbalance of an electrical supply network generates a phase negative sequence current.
This function allows the detection of phase to phase or phase to earth fault in network
configurations for which standard over-current protections are unsuccessful:
♦ Inversion or loss of a phase
♦ Two-phase overcurrent low amplitude fault (feeders of great length)
♦ Loss of earthing system (isolated neutral)
♦ Fault in the delta windings of transformers.
This function offers a greater sensitivity than standard phase and earth overcurrent
protections.
6.2
Setting characteristics
CHARACTERISTICS
Values
Accuracy
Resetting Percentage
94 %
Response time of the instantaneous outputs
60 ms
± 1.5 %
Typical
for I ≥ 2 Is
Overshoot
< 35 ms
Time delay and threshold of function 46
Definite time delay
Setting
40 ms up to 300 s
In step of: see *
Inverse, very inverse, extremely inverse, time curves IEC
T++: 30 ms up to 3 s
in step of 0.01 s
Moderately inverse, very inverse, extremely inverse, times T++: 30 ms up to 3 s
curves ANSI/IEEE
in step of 0.01 s
Relatively Inverse time curve
100 ms with 20 s
in step of 0.1 s
Iinv threshold
0.1 up to 2.4 In
in step of 0.1 In
Accuracy
± 2 % or ± 20 ms
Class 5
Class 5
Class 5
±5%
for Iphase > 0.3 In
*: from 0.04 up to 9.99 s in step of 0.01 s, 10.0 s up to 29.9 s in step of 0.1 s, 30 up to 300 s
in step of 1s
The accurate characteristics of the curves with dependent specified time are defined in the
chapter "Tripping curves [46], [51] and [51N]".
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NP800 range
Date : 08/2006
Sheet : 21
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Issue : d
6.3
Setting example
According to the value determined by a co-ordination or a setting table study, the threshold
[46] set on the protection must be adapted to the rated value of the current transformers and
possibly corrected according to the step of the setting range. Let us consider as an example
the following data:
♦
♦
♦
♦
CT = 250/5A
In relay = 5A
Rated current of the equipment to be protected: 22A
Trip value in the event of phase negative sequence = 30% with a definite time
characteristic and a time delay of 3 s.
Calculation of the threshold and the parameters to be set on protection:
♦ The negative phase sequence unit [46] will be set as follows:
I2> = (0,3x225)/250 = 0.27 In CT, unchanged by the setting step.
The operating feature will be a definite time characteristic and the time delay set to
3s.
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NP800 range
Date : 08/2006
Sheet : 22
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7.
Minimum of Current Function [37]
7.1
Description of the function
This function is only available with one specific variant of the zero-sequence current relay
(please consult us).
This function allows detection of a minimum current for the components of the electrical
network. It can be used, for instance, to check the opening of a compensation coil.
7.2
Setting characteristics
CHARACTERISTICS
Values
Accuracy
Resetting Percentage
103 %
± 1.5 %
Response time of the instantaneous outputs
60 ms
Typical for I ≥ 2 Is
Overshoot
< 35 ms
Time delays and threshold of function 37
Definite time delay
I0< threshold
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allowed without prior authorization
Setting
40 ms up to 10 s
in step of 0.01 s
0.03 up to 2.00 in
step of 0.01 In
Application Guide
NP800 range
Accuracy
± 2 % or ± 20 ms
±5%
Date : 08/2006
Sheet : 23
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8.
Tripping Curves [46], [51] and [51N]
8.1
Time delay with definite time characteristic
The phase and earth thresholds can be chosen with a definite time delay.
The time delay integrates all the processing times of the fault until the activation of the output
relay.
The real tripping time of the relay is equal to the value of the time delay, plus an additional
time of about 15 ms.
8.2
Dependent specified time according to IEC standard
8.2.1 Equation
NPI800 and NPID800 relays allow the selection of 3 dependent specified time curves
according to the IEC 60255-4 standard.
The characteristic equation of these curves is:
⎞
⎛ K
⎟⎟
t = T * ⎜⎜
α
(I/Is)
−
1
⎠
⎝
♦ t
Tripping time
♦ I
Value of the measured current
♦ Is
Value of the programmed threshold
♦ α, K Coefficients of definition of the curves (inverse, extremely inverse…)
♦ T++ Multiplier of time setting from 0.03 s to 3 s.
These curves are limited by I values: 1,1 Is < I < 20 Is.
Type of curves
Inverse time
Very inverse time
Extremely inverse time
Limit of curves
1.1 Is < I < 20 Is
T
K
Adjustable from
0.03 up to 3 s
in step of 0.01 s
0.140
13.5
80
α
0.02
1
2
8.2.2 Choice example for a dependent specified time curve
As a non restrictive example, the following figure shows the selectivity between NPI800-1
relay as protection of a power transformer, and NPI800-2 relay used in protection of a feeder
located on the secondary side of this transformer.
The operating feature of NPI 800-2 relay is a definite time characteristic with two thresholds
and two time delays [51] [50].
An IEC inverse time characteristic authorizing significant and short time overloads was
chosen for the function [51] of NPI800-1. The characteristic of the unit [50] is definite time.
To ensure the selectivity between the two relays, the [50] threshold setting value, 300 A, of
the NPI800-2 was taken into account as a constraint.
To select the most adapted T++ curve of the relay NP800-1, it is necessary to take into
account of the following elements:
♦ curve matching at 2s for a 300 Amps current
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♦ setting value of the threshold [ 51 ] of the NP800-1 relay: 100 Amps.
This choice is carried out by applying the following formula *:
⎡⎛ I ⎞ 0,02 ⎤
t × ⎢⎜ ⎟ − 1⎥
⎥⎦
⎣⎢⎝ Is ⎠
T++ =
0.140
With:
♦ T++ = curve to be set on the relay
♦ I/Is
= multiple of setting of the threshold [ 51 ], function of the current value
♦ t
= theoretical value of the tripping time at I/Is current value
For our example:
♦ I/Is
= 3 (I=300 Amps and Is=100 Amps)
♦ t
= 2 seconds
With a result of 0.317 and corrected by the setting step of the relay, the T++ curve chosen is:
0.32.
* extrapolated formula from the calculation of IEC inverse time curves.
1000
100
NPI 800-1
10
NPI 800-2
NPI 800-1
S
NPI 800-2
T
I
M
E
1
I
N
0.10
S
E
C
O
N
D
0.01
0.5 1
10
100
1K
ICC Sec Tr
ICC Pri Tr
10K
CURRENT IN AMPERE - SCALE x10^1
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The following formulas * can be used for the choice of:
♦ Very inverse IEC curve:
⎡⎛ I ⎞
⎤
t × ⎢⎜ ⎟ − 1⎥
⎢⎣⎝ Is ⎠
⎥⎦
T++ =
13,5
♦ Extremely inverse IEC curve:
⎡⎛ I ⎞2 ⎤
t × ⎢⎜ ⎟ − 1⎥
⎣⎢⎝ Is ⎠
⎦⎥
T++ =
80
With:
♦ T++
♦ I/Is
♦ T
= curve to be set on the relay
= multiple of setting of the threshold [51], function of the current value
= theoretical value of the tripping time at I/Is current value
* extrapolated formula from the calculation of IEC inverse time curves
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8.2.3 IEC - Inverse Time Curves
t=
0.140 T + +
for 1.1Is < I < 20 Is
(I/Is) 0.02 − 1
Inverse (CEI)
1000,000
T++ = 3 s
T++ = 1 s
T++ = 0,5 s
T++ = 0,1 s
T++ = 0,03 s
100,000
t (seconds)
10,000
1,000
0,100
0,010
1
10
100
I/Is
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8.2.4
IEC - Very Inverse Time Curves
t=
13.5 T + +
for 1.1Is < I < 20 Is
(I/Is) − 1
Very inverse CEI
1000,000
100,000
T++ = 3 s
T++ = 1 s
T++ = 0,5 s
T++ = 0,1 s
T++ = 0,03 s
t (seconds)
10,000
1,000
0,100
0,010
1
10
100
I/Is
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8.2.5 IEC - Extremely Inverse Time Curves
t=
80 T + +
for 1.1Is < I < 20 Is
(I/Is) 2 − 1
Extremely Inverse (CEI)
10000,000
1000,000
T++ = 3 s
T++ = 1 s
T++ = 0,5 s
T++ = 0,1 s
T++ = 0,03 s
t (seconds)
100,000
10,000
1,000
0,100
0,010
1
10
100
I/Is
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8.3
Dependent specified time according to ANSI/IEEE standard
8.3.1 Equation
NPI800 and NPID800 relays allow the selection of 3 dependent specified time curves
according to the ANSI/IEEE standard.
The characteristic equation of these curves is:
⎛ A
⎞
+ B ⎟⎟
t = T * ⎜⎜
α
⎝ (I/Is) − 1
⎠
♦
♦
♦
♦
t
Tripping time *
I
Value of the measured current
Is
Value of the programmed threshold
α, A, B
Coefficients of definition of the curves (inverse, very inverse or
extremely inverse)
♦ T ++
Multiplier of time setting between 0.03 and 3 s.
These curves are limited by I values: 1.1 Is < I < 20 Is.
Type of curve
Limit of curves
Moderately inverse time
1.1 Is < I < 20 Is
Very inverse time
1.1 Is < I < 20 Is
Extremely inverse time
1.1 Is < I < 20 Is
T
A
Adjustable from
0.03 up to 3
seconds
(according to
type of curve)
α
B
0.0515
0.02
0.1140
19.61
2
0.4910
28.2
2
0.1217
8.3.2 Setting advises
Refer to the examples related to standard IEC 60255-4.
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8.3.3 ANSI/IEEE - Moderately Inverse Time Curves
⎛ 0.0515
⎞
⎟⎟ for 1.1 Is < I < 20 Is
t = T * ⎜⎜
+
0
.
1140
0.02
⎝ (I/Is) − 1
⎠
Moderately Inverse (ANSI / IEEE)
100,000
T++ = 3 s
T++ = 1 s
T++ = 0,5 s
10,000
T++ = 0,1 s
t (seconds)
T++ = 0,03 s
1,000
0,100
0,010
0
1
10
100
I/Is
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8.3.4 ANSI/IEEE – Very Inverse Time Curves
⎛ 19.6
⎞
t = T * ⎜⎜
+ 0.4910 ⎟⎟ for 1.1 Is < I < 20 Is
2
⎝ (I/Is) − 1
⎠
Very Inverse (ANSI / IEEE)
1000,000
100,000
T++ = 3 s
T++ = 1 s
T++ = 0,5 s
T++ = 0,1 s
T++ = 0,03 s
t (seconds)
10,000
1,000
0,100
0,010
0
1
10
100
I/Is
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8.3.5 ANSI/IEEE – Extremely Inverse Time Curves
⎛ 28.2
⎞
t = T * ⎜⎜
+ 0.1217 ⎟⎟ for 1.1Is < I < 20 Is
2
⎝ (I/Is) − 1
⎠
Extremely Inverse (ANSI / IEEE)
1000,000
T++ = 3 s
T++ = 1 s
T++ = 0,5 s
T++ = 0,1 s
100,000
T++ = 0,03 s
t (seconds)
10,000
1,000
0,100
0,010
0
1
10
100
I/Is
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8.4
Definite time characteristic for electromechanical relays type (RI curves)
8.4.1 Equation
Relays NPI800 and NPID800 allow the selection of Relatively Inverse time curve of
electromechanical type.
The characteristic equation of this curve is:
t=
T++
0.236
0.339 (I/Is )
for 1.1 Is < I < 20 Is
8.4.2 Application
This characteristic is recommended in case of no required selectivity with former protections
of the network.
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8.4.3 Relatively Inverse Curves
Relatively Inverse Curves
1000,0
T++ = 20 s
T++ = 16 s
T++ = 12 s
T++ = 8 s
T++ = 6 s
T++ = 4 s
T++ = 2 s
T++ = 1 s
T++ = 0.8 s
T++ = 0.6 s
T++ = 0.4 s
T++ = 0.2 s
T++ = 0.1 s
t (seconds)
100,0
10,0
1,0
0,1
1,0
1.2
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10,0
100,0
I/Is
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8.5
User programmable Dependent Time Curves
Relays NP800 are designed to operate according to two configurable inverse time curves.
These curves must be defined by the user and will be downloaded by ICE in its factory.
Please consult us.
As for IEC or ANSI/IEEE standard dependent specified time curves, these two characteristics
can then be used by the functions of protection:
♦ Phase protection [51-1] and [51-2]
♦ Earth-fault protection [51N]
♦ Negative sequence overcurrent protection [46].
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9.
Detection of Broken Conductor Function [46 BC]
9.1
Description of the function
The fault corresponds to the opening of a current circuit, for instance due to break of a
conductor.
This type of faults does not produce significant overcurrent value. Consequently, it cannot be
detected by the functions [50] or [51].
The percentage of unbalance under normal operation varies. On the other hand, it is
modified in the event of rupture of the conductor.
Percentage.of .unbalance =
.
.
I .negative.sequence
I . positive .sequenece
The measurement of the percentage of unbalance allows the detection of the opening of a
circuit.
The detection of negative sequence current is not very sensitive in the case of weak load
line.
It also must be reminded that the value of the percentage of unbalance can vary according to
the localization of the fault.
9.2
Setting characteristics
CHARACTERISTICS
Values
Accuracy
Resetting Percentage
94 %
± 1.5 %
Response time of the instantaneous outputs
60 ms
Minimum negative sequence current to enable the
function
Overshoot
Time delay and threshold of function 46BC
Definite time delay
Threshold
sequence
I2/I1>
Negative
sequence/
Positive
Threshold I2/I1> > Negative sequence/ Positive
sequence
9.3
Typical for I ≥ 2 Is
I2 > 0.08 In
< 35 ms
Setting
40 ms up to 300
s
10 up to 250 %
Accuracy
± 2 % or ± 20 ms
10 up to 250 %
±5%
for Iphase > 0.3 In
±5%
for Iphase > 0.3 In
Setting advises
Let us consider as an example the following data:
♦ Trip value calculated in the event of broken conductor detection: 25%
♦ Definite time delay: 20 s.
Calculation of the threshold to be set on protection:
The broken conductor unit [46BC] will be set as follows: I2/I1 = 0.25.
The operating feature will be a definite time characteristic and the time delay set at 20 s.
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10. Over-voltage Function [59]
Protection allows supervising phase to phase voltages or phase to neutral voltage (threephase or single voltage input).
It is necessary at commissioning, according to wiring of the protection, to set the type and the
number of voltages to be supervised:
♦ three phase to phase voltages (or phase to neutral) U12 (V1), U23 (V2) and U31 (V3)
♦ two phase to phase voltage (or phase to neutral): U12 (V1) and U23 (V2)
♦ one phase to phase voltage (or phase to neutral): U12 (V1).
In case of monitoring of phase to neutral voltages, a trip and a signalling output relay can be
assigned to each phase.
10.1 Description of the function
This function ensures the detection of abnormal overvoltages on a three-phase network.
Protection supervises phase to phase voltages U23, U12 and U31 or phase to neutral
voltages V1, V2 and V3 by comparison to a high threshold and a very high threshold. Each
threshold can be put in or out of order when setting parameters.
As soon as the value of one of the three voltages exceeds one of the thresholds, an alarm is
generated by the instantaneous output and simultaneously a time delay is started.
At the end of the time delay the delayed output is activated.
As soon as all the three voltages decrease under 97 % of the threshold (3 % resetting
percentage), protection recovers its initial status.
The setting of the thresholds is carried out as a percentage of the relay nominal voltage Un,
whatever the wiring (phase to neutral voltages or phase to phase voltages).
10.2 Examples
The function allows a normal setting according to following examples':
♦ Phase to neutral voltage mode:
Un = 63.3 V,
threshold = 110 % Un
= > detection of the fault is carried out when Vx > 1.1 * 63.3 = 70 V
♦ Phase to phase voltage mode:
Un = 110 V,
threshold = 120 % Un
= > detection of the fault is carried out when Uxy> 1.2 * 110 = 132 V.
However, "abnormal" settings are also tolerated by the relay:
♦ Phase to neutral voltage mode:
Un = 63.3 V,
threshold = 120 % Un
= > detection of the fault is carried out when Vx > 1.2 * 63.3 = 76 V
♦ Phase to phase voltage mode:
Un = 110 V,
threshold = 40 % Un
= > detection of the fault is carried out when Uxy > 0.4 * 110 = 44 V.
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10.3 Setting characteristic
CHARACTERISTICS
Values
Resetting Percentage
97 %
Response time of the instantaneous outputs
Overshoot
Time delay and thresholds of function 59
Definite Time delay:
t(U >) – t(U > >)
High-set U >
Very high-set U > >
60 ms
< 55 ms
Accuracy
± 1%
typical
Setting
60 ms up to 300 s
in step of: see *
Accuracy
± 2 % or ± 20 ms
0.40 up to 2.00 Un
in step of 0.01 Un
0.40 up to 2.00 Un
in step of 0.01 Un
±5%
±5%
* 0.06 up to 9.99s in step of 0.01s, 10 up to 29.9s in step of 0.1s, 30 up to 300s in step of 1s.
10.4 Setting example
According to the value determined by a co-ordination study or a settings table, the thresholds
[59] set on protection must be adapted to the rated value of the voltage transformers (PT)
and be parameterized according to the steps of the setting range.
Let us consider as an example the following data:
♦ Network 6 kV
♦ PT = 6 kV / 3 / 100 V / 3
♦ Value of trip calculated in the event of overvoltage for the first level: 6.6 kV with a
definite time delay of 1 s
♦ Value of trip calculated in the event of overvoltage for the second level: 7.2 kV with a
definite time delay of 0.5 s.
Calculation of the thresholds and parameters to be set on protection:
♦ For the first level, the high-set unit U > of the function [59] will be set as follows:
U > = 6.6/6 = 1.1
The t(U>) time delay will be set at 1 s.
♦ For the second level, the very high-set unit U >> of the function [59] will be set as
follows:
U >> = 7.2/6 = 1.2
The t(U>>) time delay will set at 0.5 s.
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11. Under Voltage Function [27]
11.1 Description of the function
Warning: If the function [27P] is use this function is put automatically out of service.
This function ensures the detection of voltage drops due for instance to dysfunctions of
voltage regulation, or losses of excitation of generators…
As soon as the value of one of the monitored voltages is lower than the set thresholds, an
alarm is generated (instantaneous output) and simultaneously a time delay is started. At the
end of the time delay, the delayed output is activated.
When the three voltages again exceed 103 % of threshold (3 % percentage of release)
protection recovers its initial status.
The setting of the thresholds is carried out as a percentage of the relay nominal voltage Un,
whatever the wiring (phase to neutral voltages or phase to phase voltages).
Example:
♦ Phase to neutral voltage mode:
Un = 63.3 V,
threshold = 40 % Un
= > detection of the fault is carried out when Vx < 0.4 * 63.3 = 25.3 V
♦ Phase to phase voltage mode:
Un = 110 V,
threshold = 40 % Un
= > detection of the fault is carried out when Uxy < 0.4 * 110 = 44 V.
In case of monitoring of phase to neutral voltages, a trip and a signalling output relay can be
assigned to each phase.
To prevent useless alarms during reclosing cycles or during connection of the relay to a dead
voltage network, the under-voltage function can be inhibited when the measured voltage is
lower than 10 % Un (threshold of inhibition). The measurement of the inhibition threshold is
done input by input with the phase to neutral mode and thanks to one “or” function with the
phase to phase mode.
11.2 Setting characteristics
CHARACTERISTICS
Values
Resetting Percentage
103 %
Response time of the instantaneous outputs
Overshoot
Optional threshold of inhibition of under-voltage
function
Time delay of function 27
Definite time delay:
t(U<) t(U<<)
IEC Inverse time curves IEC:
t(U<) – t(U<<)
IEC Very inverse time curves:
t(U<) – t(U<<)
IEC Extremely inverse time curves:
60 ms
< 55 ms
10 % Un
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Accuracy
± 1%
typical
Setting
40 ms up to 300 s
In step of: see *
Accuracy
± 2 % or ± 20 ms
T++: 30 ms up to 3 s
in step of 0.01s
Class 5
T++: 30 ms up to 3 s
in step of 0.01s
Class 5
T++: 30 ms up to 3 s
Class 5
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t(U<) – t(U<<)
ANSI/IEEE Moderately inverse time curves:
t(U<) – t(U<<)
ANSI/IEEE Very inverse time curves:
t(U<) – t(U<<)
ANSI/IEEE Extremely inverse time curves:
t(U<) – t(U<<)
Thresholds of function 27
Low-set
(U<)
Very low-set
(U<<)
in step of 0.01s
T++: 30 ms up to 3 s
in step of 0.01s
Class 5
T++: 30 ms up to 3 s
in step of 0.01s
Class 5
T++: 30 ms up to 3 s
in step of 0.01s
Class 5
Setting
0.05 up to 1.20 Un
in step of 0.01 Un
0.05 up to 1.20 Un
in step of 0.01 Un
Accuracy
±5%
±5%
* 0.04 up to 9.99s in step of 0.01s, 10 up to 29.9s in step of 0.1s, 30 up to 300s in step of
1s
The accurate characteristics of the curves with dependent specified time are defined in the
chapter "Tripping curves [27], [27P], [59] and [59N]".
11.3 Setting example
According to the value determined by a co-ordination study or a settings table, the thresholds
[27] set on protection must be adapted to the rated value of the voltage transformers (PT)
and parameterized according to the steps of the setting range.
Let us consider as an example the following data:
♦ Network 6 kV
♦ PT = 6 kV / 3 / 100 V / 3
♦ Value of calculated trip value in the event of undervoltage for the first level: 5.1 kV
with a definite time delay of 1 s.
♦ Value of calculated trip value in the event of undervoltage for the second level: 4.2 kV
with a definite time delay of 0.5 s.
Calculation of the thresholds to be set on protection:
♦ For the first level, the low-set unit U< of the function [27] will be set as follows:
U< = 5.1/6 = 0.85.
The t(U<) time delay will be set at 1 s.
♦ For the second level, the very low-set unit U<< of the function [27] will be set as
follows:
U<< = 4.2/6 = 0.7.
The t(U<<) time delay will be set at 0.5 s.
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12. Positive Sequence Voltage Drops Function [27P]
12.1 Description of the function
Warning: If this function is use the function [27] is put automatically out of service.
By the measurement of the positive sequence component*, this function ensures an overall
three-phase voltage supervision or rotating machine torque in the case of temporary or
permanent operation (single phase reclose) with an unbalanced network. The calculation of
the positive sequence voltage is carried out from the phase to neutral or phase to phase
voltages applied to the three analogue inputs of the relay.
As soon as the value of the positive sequence of the monitored voltages is lower than the set
thresholds, an alarm is generated (instantaneous output) and simultaneously a time delay is
started. At the end of the time delay, the delayed output is activated.
When the three voltages again exceed 103 % of threshold (3 % percentage of release)
protection recovers its initial status.
* measurement implying a connection of the three inputs voltage to a three-phase network,
phase to neutral voltages or phase to phase voltages.
The setting of the thresholds is carried out as a percentage of the relay nominal voltage Un,
whatever the wiring (phase to neutral voltages or phase to phase voltages).
Example:
♦ Phase to neutral voltage mode:
Un = 63.3 V,
threshold = 85 % Un
= > detection of the fault is carried out when Vd < 0.85 * 63.3 = 53.8 V
♦ Phase to phase voltage mode:
Un = 110 V,
threshold = 85 % Un
= > detection of the fault is carried out when Ud < 0.85 * 110 = 93.5 V.
The function can be inhibited when the positive sequence voltage measured is lower than 10
% Un (threshold of inhibition).
12.2 Caractéristiques de réglages
CHARACTERISTICS
Values
Resetting Percentage
103 %
Response time of the instantaneous outputs
Overshoot
Optional threshold of inhibition of under-voltage
function
Time delay of function 27P
Definite time delay:
t(Ud<) t(Ud<<) t(Ud<<<)
Thresholds of function 27P
Low-set
Ud<
Very low-set
Ud<<
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60 ms
< 55 ms
10 % Un
Setting
40 ms up to 300 s
In step of: see *
Setting
0.05 up to 1.20 Un
in step of 0.01 Un
0.05 up to 1.20 Un
in step of 0.01 Un
Accuracy
±1%
typical
Accuracy
± 2 % ou ± 20 ms
Accuracy
±5%
±5%
Date : 08/2006
Sheet : 42
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Very very low-set
Ud<<<
0.05 up to 1.20 Un
in step of 0.01 Un
±5%
* 0.04 up to 9.99s in step of 0.01s, 10 up to 29.9s in step of 0.1s, 30 up to 300s in step of 1s
12.3 Setting example
According to the value determined by a co-ordination study or a settings table, the thresholds
[27P] set on protection must be adapted to the rated value of the voltage transformers (PT)
and parameterized according to the steps of the setting range.
Let us consider as an example the following data:
♦ Network 6 kV
♦ PT = 6 kV / 3 / 100 V / 3
♦ Value of calculated trip value in the event of drop of positive sequence voltage for the
first level: 5.1 kV with a definite time delay of 1 s.
♦ Value of calculated trip value in the event of drop of positive sequence voltage for the
second level: 4.2 kV with a definite time delay of 0.5 s.
Calculation of the thresholds to be set on protection:
♦ For the first level, the low-set unit Ud< of the function [27P] will be set as follows:
Ud< = 5.1/6 = 0.85.
The t(Ud<) time delay will be set at 1 s.
♦ For the second level, the very low-set unit Ud<< of the function [27P] will be set as
follows:
Ud<< = 4.2/6 = 0.7.
The t(Ud<<) time delay will be set at 0.5 s.
♦ The third level, the very very low-set unit Ud<<< of the function [27P] will be put out of
service.
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13. Zero-sequence Over-Voltage Function [59N]
13.1 Description of the function
This function ensures the detection of earth-faults.
Two versions of NPUH800 relays, to be determined at the order, allow the measurement of
the zero-sequence voltage either by a measured zero sequence voltage, or calculated by
measurement of the three-phase voltages.
Protection monitors the zero-sequence voltage by comparison to a low threshold and a high
threshold. Each threshold can be put in or out of order when setting parameters.
As soon as the value of the voltage exceeds one of the set thresholds, an alarm is generated
by the instantaneous output and simultaneously a time delay is started.
13.2 Setting characteristics
CHARACTERISTICS
Values
Accuracy
Resetting Percentage
Response time of the instantaneous outputs
97 %
60 ms
Overshoot
< 55 ms
Time delay and thresholds of function 59N
Definite time delay
t(Uo >) – t(Uo > >)
Low-set
Uo >
High-set
Uo > >
Setting
60 ms up to 300 s
In step of: see *
Accuracy
± 2 % or ± 20 ms
0.02 up to 0.80 Un
in step of 0.01 Un
±2%
0.02 up to 0.80 Un
in step of 0.01 Un
±2%
typical for Vo ≥ 2 Vs
* 0.06 up to 9.99s in step of 0.01s, 10 up to 29.9s in step of 0.1s, 30 up to 300s in step of 1s.
13.3 > Setting example
According to the value determined by a co-ordination study or a setting table, the thresholds
[59N] set on protection must be adapted to the rated value of the voltage transformers (PT)
and be parameterized according to the steps of the setting range.
According to the application and the type of relay, the V0 zero-sequence voltage, is
calculated from the measurement of the phase to neutral voltages V1, V2, V3 or measured
from the residual voltage supplied by three voltage transformers connected in open delta.
Note: the residual voltage Vr is equal to three times the zero-sequence voltage V0.
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13.3.1 Setting example in measured mode
Let us consider as an example the following data:
♦ Network 6 kV
♦ TP = 6 kV / 3 / 100 V / 3 Unrel = 57.7 V
♦ Value of calculated trip in the event of earth-fault for the first level: 10% of the phase
to neutral network voltage with a definite time delay of 1 s.
♦ Value of calculated trip in the event of earth-fault for the second level: 20% of the
phase to neutral network voltage with a definite time delay of 0.5 s.
Calculation of the thresholds to set on protection:
♦ For the first level, the low-set unit Uo > of the function [59N] will be set as follows:
Taking into account the star/open delta PT connection, the voltage applied to the
relay will be equal to the triple of the measured voltage. (i.e. Vr)
Uo> = 0.1 x 3 x Unrel = 0.3 Unrel
The t(Uo>) time delay will be set at 1 s.
♦ For the second level, the high-set unit Uo >> of the function [59N] will be set as
follows:
Taking into account the star/open delta PT connection, the voltage applied to the
relay will be equal to the triple of the measured voltage.
Uo>> = 0.2 x 3 x Unrel = 0.6 Unrel
The t(Uo>>) time delay will be set at 0.5 s.
13.3.2 Setting example in calculated mode
Let us consider as an example the following data:
♦ TP = 6 kV / 3 / 100 V / 3 Unrel = 57.7 V
♦ Value of calculated trip in the event of earth-fault for the first level: 10% of the phase
to neutral network voltage with a definite time delay of 1 s.
♦ Value of calculated trip in the event of earth-fault for the second level: 20% of the
phase to neutral network voltage with a definite time delay of 0.5 s.
Calculation of the thresholds to set on protection:
♦ For the first level, the low-set unit Uo > of the function [59N] will be set as follows:
U0 > = 0.1 x Unrel = 0.1 Unrel.
The t(Uo>) time delay will be set at 1 s.
♦ For the second level, the high-set unit Uo >> of the function [59N] will be set as
follows:
U0 > > = 0.2 x Unrel = 0.2 rel
The t(Uo>>) time delay will be set at 0.5 s.
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14. Tripping Curves [27], [27P], [59] and [59N]
14.1 Definite time delay [27], [59] and [59N]
The phase and earth thresholds can be chosen with a definite time delay.
The time indicated integrates all the processing times of the fault until activation of the output
relay.
The real tripping time of the relay is equal to the value of the time delay, plus an additional
time of about 15 ms.
14.2 Dependent specified time according to IEC standards [27]
14.2.1 Equation
Considering the under-voltage [27] function, NPU800 relays allow the selection of 3
dependent specified time curves according to IEC standards.
The characteristic equation of these curves is:
⎛ k × (U / Us )
t = ⎜⎜
α
⎝ 1 − (U / Us )
α
⎞
⎟×T + +
⎟
⎠
♦ T
Tripping time
♦ U
Value of the measured voltage
♦ Us
Value of the programmed threshold
♦ α, K Coefficients of definition of the curves (inverse, extremely inverse…)
♦ T ++ Multiplier of time setting between 0.03 and 3 s
These curves are limited to settings between 0.9 > U/Us > 0.2
Type of curves
Inverse time
Very inverse time
Extremely inverse time
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Limit of curves
0.2 U < Us< 0.9 U
T
K
Adjustable
from 0.03 up to
3 seconds
Application Guide
NP800 range
0.140
13.5
80
α
0.02
1
2
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Sheet : 46
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14.2.2 IEC - Inverse Time Curves
⎛ 0.14 × (U / Us )0.02 ⎞
⎟ × T + + for U/Us < 0.9
t = ⎜⎜
0.02
⎟
1
(
/
)
−
U
Us
⎠
⎝
1000,00
T++ = 3 s
T++ = 1 s
T++ = 0,5 s
T++ = 0,1 s
T++ = 0,03 s
100,00
t (seconds)
10,00
1,00
0,10
0,01
0,1
1,0
U/Us
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14.2.3 IEC - Very Inverse Time Curves
⎛ 13.5 × (U / Us )
t = ⎜⎜
⎝ 1 − (U / Us )
⎞
⎟ × T + + for U/US < 0.9
⎟
⎠
1000,00
T++ = 3 s
T++ = 1 s
T++ = 0,5 s
T++ = 0,1 s
T++ = 0,03 s
100,00
t (seconds)
10,00
1,00
0,10
0,01
0,10
1,00
U/Us
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14.2.4 IEC - Extremely Inverse Curves
⎛ 80 × (U / Us )2 ⎞
⎟ × T + + for U/Us < 0.9
t = ⎜⎜
2 ⎟
−
U
Us
1
(
/
)
⎝
⎠
T++ = 3 s
T++ = 1 s
T++ = 0,5 s
T++ = 0,1 s
T++ = 0,03 s
1000,00
100,00
t (seconds)
10,00
1,00
0,10
0,01
0,10
1,00
U/Us
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14.3 Dependent specified time according to ANSI/IEEE standards [27]
14.3.1 Equation
Considering the under-voltage function [27], NPU800 relays allow the selection of 3
dependent specified time curves according to ANSI/IEEE standards.
The characteristic equation of these curves is:
⎛ A × (U / Us )α
⎞
t = ⎜⎜
+ B ⎟⎟ × T + +
α
⎝ 1 − (U / Us )
⎠
♦
♦
♦
♦
T
Tripping time
U
Value of the measured voltage
Is
Value of the programmed threshold
α, A, B
Coefficients of definition of the curves (inverse, very inverse or
extremely inverse)
♦ T++
Multiplier of time setting between 0.03 and 3 s
These curves are limited to settings between 0.9 > U/Us > 0.2
Type of curves
Moderately inverse time
Very inverse time
Extremely inverse time
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Limit of curves
0.2 U < Us < 0.9 U
Application Guide
NP800 range
T
Adjustable
from 0.03 to
3 seconds
A
α
B
0.0515
19.61
28.2
0.02
2
2
0.1140
0.4910
0.1217
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14.3.2 ANSI/IEEE - Moderately Inverse Time Curves
⎛ 0.0515 × (U / Us )0.02
⎞
t = ⎜⎜
+ 0.1140 ⎟⎟ × T + + for U/Us < 0.9
0.02
⎝ 1 − (U / Us )
⎠
1000,00
T++ = 3 s
T++ = 1 s
T++ = 0,5 s
T++ = 0,1 s
T++ = 0,03 s
t (seconds)
100,00
10,00
1,00
0,10
0,01
0,10
1,00
U/Us
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14.3.3 ANSI/IEEE - Very Inverse Time Curves
⎛ 19.61 × (U / Us )2
⎞
⎟ × T + + for U/Us < 0.9
t = ⎜⎜
+
0
.
491
2
⎟
1
−
U
/
Us
(
)
⎝
⎠
1000,00
T++ = 3 s
T++ = 1 s
T++ = 0,5 s
T++ = 0,1 s
T++ = 0,03 s
100,00
t (seconds)
10,00
1,00
0,10
0,01
0,10
1,00
U/Us
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14.3.4 ANSI/IEEE - Extremely Inverse Time Curves
⎛ 28.2 × (U / Us )2
⎞
t = ⎜⎜
+ 0.1217 ⎟⎟ × T + + for U/Us < 0.9
2
⎝ 1 − (U / Us )
⎠
1000,00
T++ = 3 s
T++ = 1 s
T++ = 0,5 s
T++ = 0,1 s
T++ = 0,03 s
100,00
t (seconds)
10,00
1,00
0,10
0,01
0,10
1,00
U/Us
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15. Under and Over Frequency Function [81]
15.1 Description of the function
The measurement of the frequency is carried out from the positive sequence component of
the voltage calculated by protection, in order to obtain a significant accuracy of measurement
even during the falls of voltages due to phase to phase faults.
15.2 Setting characteristics
CHARACTERISTICS
Values
Value of release
Maximum response time of the outputs
Overshoot
Operating voltage
0.2 Hz
< 150 ms
< 55 ms
> 0.10 Un
Over-frequency Function
F >, F > >, F > > >, F > > > >
Time delay
Threshold (Fn = 50 Hz)
Threshold (Fn = 60 Hz)
Under-frequency function
F<, F<<, F<<<, F<<<
Time delay
Threshold (Fn = 50 Hz)
Threshold (Fn = 60 Hz)
Accuracy
± 0.1 Hz
Setting
80 ms up to 10 s
in step of 10 ms
50.01 up to 54.0 Hz
in step of 0.01 Hz
60.01 up to 64.0 Hz
in step of 0.01 Hz
Setting
80 ms up to 10 s
in step of 10 ms
46.0 up to 49.99 Hz
in step of 0.01 Hz
56.0 up to 59.99 Hz
in step of 0.01 Hz
Accuracy
± 2 % or ±20 ms
± 0.1 Hz
± 0.1 Hz
Accuracy
± 2 % or ±20 ms
± 0.1 Hz
± 0.1 Hz
Out of the range of operation, the accuracy is not guaranteed.
Below 10% of Fn, the function is inhibited.
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16. Thermal Image Cable and Transformer Function [49]
This function ensures the detection of thermal overload. Two types of thermal images are
implemented in the NPI800 and NPID800 overcurrent relays:
♦ The Cable thermal image function ensures the protection of the cables against the
long-standing overloads. The calculation of the thermal image is carried out by phase
♦ The Transformer thermal image function ensures the protection of the power
transformers against overloads. The calculation of the thermal image is carried out
using the positive sequence component of the current. This function allows to use a
cooling time constant different from the heating one.
According to the need and the type of relay, the User will select one of the two modes.
16.1 Cable thermal image Function [49]
16.1.1 Description of the function
The principle of this type of protection is that the heat released inside a cable corresponds to
an ohmic loss R I² t. So, by carrying out an integration of the current, an image of the thermal
state of the protected can be obtained.
The tripping time after detection of an overload current is given by the following formula
(according to standard IEC 255-8):
⎛ I 2 − Ipre 2
t = C ∗ ln⎜⎜ 2
2
⎝ I − Ib
♦
♦
♦
♦
♦
I
t
C
Ipre
IB
⎞
⎟⎟
⎠
= overload current.
= tripping time after detection of the overload.
= heating and cooling time-constant of the element to be protected.
= current before the overload.
= reference current for which the cable reaches a maximum thermal state of
100%.
The trip is obtained when the thermal state of the protected element reaches 100 %.
Thermal alarm is enabled when the thermal state reaches the thermal alarm threshold: 80%
up to 100 %.
The curve, showed next page, indicates the tripping time according to the preload current Ipre,
for a time-constant C = 10 min.
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16.1.2 Setting characteristics
CHARACTERISTICS
Heating and cooling Time-constant
Thermal alarms threshold
Thermal trip threshold (reference current Iref)
Restarting thermal threshold inhibition
Values
Accuracy
4 min up to 180 min
in step of 1 min
80 up to 100 % Thermal
state in step of 1%
0.4 up to 1.3 In
in step of 0.01 In
40% up to 100 % Thermal
state in step of 1%
Class 5
Class 5
Class 5
Class 5
16.1.3 Setting example
According to the value determined by a co-ordination study or settings table, the threshold
[49] set on protection must be adapted to the rated current of the current transformers (CT)
and possibly corrected according to the steps of the setting range. Let us consider as an
example the following data to protect a cable:
♦ CT = 500/5 Amps
♦ In Relay = 5 Amps
♦ Value of the calculated trip for the thermal threshold * = 565 Amps
♦ Heating time-constant = 60 min. (given by the transformer maker)
♦ Restarting thermal threshold inhibition = 90% of the thermal state
* function of the following data’s of the cable maker:
♦ Maximum current rating in steady state condition,
♦ Acceptable current density under overload condition.
Calculation of threshold and parameters to be set on protection:
The Ib trip threshold will be set at the following value: Ib = 565/500 = 1.13.
The heating time-constant will be set at the required value: 60 min.
Implicitly, the cooling time constant will be also 60 min.
The restarting thermal threshold inhibition will be set at the required value: 90%
In addition, the thermal alarm threshold could be set at 95% and thus warns the operator
before trip.
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16.2 Transformer Thermal image Function [49]
16.2.1 Description of the function
This function is used to protect a power transformer against an excessive rise of its
temperature, due to a long overload.
When the calculated thermal state reaches 100 %, the supply of the transformer is stopped.
This state is obtained at the end of a t time given by the following relation (Standard IEC 60
255-8):
⎛
⎜ I transf 2 − I pre 2
t = C t ∗ ln⎜
2
⎜ I transf − I b ²
⎝
♦ Ct
♦ IB
♦ Ipre
♦ Itransf
⎞
⎟
⎟
⎟
⎠
= thermal time-constant of the transformer
= reference current for which the transformer reaches a maximum thermal
state of 100 % in stabilised mode
= current of load at the initial status
= real current of load of the transformer at the t time
I transf
=
I pos ² + K * I neg ²
In order to give a more realistic image of the thermal stress bore by the power transformer,
the thermal image calculation takes into account the positive and the negative phase
sequence components of the current, balanced by a factor K (representative of the
unbalance).
The positive and the negative phase sequence components are calculated from the three
currents phases.
A thermal alarm is generated when the thermal state reaches an adjustable alarm threshold
from 80 up to 100 %.
The thermal trip occurs for a thermal state of 100 %.
16.2.2 Value of the Time-constant Ct
The time-constant Ct of a power transformer is different according to its operating mode. To
take into account this criterion, the thermal image of the NPI800 and NPID800 relays is
calculated according to three operating modes:
16.2.2.1 Closing function
During the energizing time of a power transformer, the presence of inrush currents involves a
heating faster than in normal circumstances. In order to integrate this phenomenon, the CTE
heating time-constant used in the calculation of the relay can decrease consequently.
So, when the dedicated input: "Closing mode" is activated, the CTE heating time-constant is
multiplied by a factor FD lower than 1 (factor of reclosing). Weighting lasts the time set in the
function "closing mode".
Thermal time-constant to the reclosing: Ct = FD * CTE
NOTE: in order that the "closing mode" function does not balance the calculation of the
heating time-constant of the thermal image CTE, the FD factor must be set at 1.
16.2.2.2 Normal operating mode
The normal operating mode starts at the end of the “closing function" time delay.
Normal operating thermal time-constant: Ct = CTE
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16.2.2.3 Cooling mode (I trans < 0.15 In)
As soon as the transformer is not supplied any more, the time-constant increases because of
the less effectiveness (even stop) of the cooling system.
Thermal time-constant under cooling operation: Ct = 1.0 up to 6.0 * CTE
16.2.3 Setting characteristics
CHARACTERISTICS
CTE : heating time constant
CTR: cooling time-constant
K: negative sequence factor
FD: Closing factor
Thermal reference current IB
Thermal alarm threshold
Restarting thermal threshold inhibition
Values
Accuracy
4 min up to 180 min
in step of 1 min
1.0 up to 6.0 CTE
in step of 0.1
0 up to 9
in step of 1
50 up to 100 %
in step of 1%
0.40 up to 1.30 In
in step of 0.01 In
80 up to 100 %
in step of 1%
Class 5
40 up to 100 % Thermal state
in step of 1%
Class 5
Class 5
Class 5
Class 5
16.2.4 Setting example
According to the value determined by a co-ordination study or settings table, the threshold
[49] set on protection must be adapted to the rated current of the current transformers (CT)
and possibly corrected according to the steps of the setting range. Let us consider as an
example the following data to protect a power transformer:
♦ CT = 250/5 A
♦ In Relay = 5 A
♦ Rated current of the transformer = 210A
♦ Heating time-constant * = 60 min.
♦ Transformer with natural circulation of oil and air (ONAN)
* manufacturer’s data
Calculation of the threshold and parameters to be set on protection:
The Ib trip threshold will be set at the following value: Ib = (210/250)x1.07** = 0.898,
corrected by the setting step: 0.90.
The heating time-constant will be set at the required value: 60 min.
According to the cooling process, the cooling time constant will be also set at 60 min. (CTR =
CTE)
The restarting thermal threshold inhibition will be set at the required value: 90%
The installation not being subject to significant unbalanced currents, the negative sequence
weighting factor will be set to 0. So the unbalances will not be taken into account in the
calculation of the thermal image.
The closing factor will be set at 100%, not balancing thus the heating time constant.
In addition, the thermal alarm threshold could be set at 90% and thus warns the operator
before trip.
** continuous overload factor
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16.3 Thermal heating curves (cable and transformer)
16.3.1 Characteristic of the thermal image
This curve is defined for a time-constant equal to 10 minutes:
t(s)
1000
8
100
Ipre = 0
Ipre = 0.40 (Θ = 16 %)
10
Ipre = 0.60 (Θ = 36 %)
Ipre = 0.80 (Θ = 64 %)
Ipre = 0.90 (Θ = 81 %)
1
1
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10
100
Application Guide
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I/Ib
Date : 08/2006
Sheet : 59
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Issue : d
τ = 10 min
16.3.2 Thermal cooling curves (cable and transformer)
The following curve indicates the necessary time for the cooling, starting from an initial
thermal state with no transformer current flowing.
The curves correspond to a time-constant cooling CTR of 1 min.
For another value of time-constant, it is necessary to multiply the indicated times of the curve
by the value of the time-constant used in minutes.
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16.4 Hot Restarting Inhibition - Cable and transformer
16.4.1 Description of the function
Sometimes manufacturers impose that no restarting or energizing of their equipment is
carried out if the operating temperature has not decreased below a specified threshold.
For NPI800 and NPID800 relays, in relation with the cable and transformer thermal functions,
it is possible to forbid energizing of the protected element until its thermal state has
decreased below an user configurable threshold.
In relation with an output relay, this function allows the control of the start of the equipment.
16.5 Setting characteristics
CHARACTERISTICS
Restarting thermal threshold inhibition
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Values
40 up to 100 % Iref
in step of 1%
Application Guide
NP800 range
Accuracy
Class 5
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Sheet : 61
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17. On Load Reclosing Function
17.1 Description of the function
This function allows avoiding, at the energizing time of the equipment, additional constraints
to the selectivity chain of the protections of a network. It allows thus, during the closing of the
circuit-breaker, to prevent the spurious trips due to inrushes of significant currents such as
the magnetizing current of the transformers and the starting current of the motors.
In this case, this function temporarily modifies the thresholds of the functions of protection
after activation of the dedicated input: "mode of reclosing". This input must be connected to a
signal representative of the closing of the circuit-breaker.
The ratio of modification is user programmable and is applied only to the chosen thresholds
of set 1 and set 2. After the set time, the thresholds are set again to their normal values.
Thresholds of relays NPI800 and NPID800 that may be modified at the closing time of a CB
are:
♦ Phase overcurrent threshold I>, I> >, I > > > [51-1] [51-2] [50]
♦ Earth fault overcurrent threshold Io>, Io> > [51N] [50N]
♦ Negative phase sequence overcurrent threshold I inv > [46]
♦ Broken conductor Low-set I inv / I D [46BC]
♦ Broken conductor High-set I inv / I D [46BC]
♦ Io> and Io>> [51N] [50N] for the NPIH800 and NPIHD800 relays
For the transformer thermal image function [49] of the NPI800 and NPID800 relays, the
dedicated input: “closing mode" acts, during the closing, on the thermal time-constant Ct.
(see the paragraph dedicated to the thermal function transformer)
Only the factor FD is taken into account. The K ratio used for the other functions of the
protection is not:
Ct = FD * CTE
17.2 Setting characteristics
CHARACTERISTICS
Values
Ratio K of the closing mode
Time of the closing mode
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50 up to 200 %
40 ms up to 300 s
Application Guide
NP800 range
Accuracy
±5%
± 2 % or 20 ms
Date : 08/2006
Sheet : 62
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18. Motor Thermal image Functions [49]
18.1 Description of the thermal image function
18.1.1 General
This function is used to protect the motor against an excessive rise of its temperature, due to
a long overload.
With NPM800 relay, the thermal state of the motor is calculated from an internal thermal
image.
When the calculated thermal state reached 100 %, the trip by this unit is ordered.
This state is obtained at the end of a t time given by the relation (IEC Standard 255-8):
⎛ I mot 2 − I pre 2 ⎞
⎟
t = Ct ∗ ln⎜⎜
2
⎟
I
I
−
²
⎝ mot
ref ⎠
= motor thermal time-constant, according to the operating mode (in seconds).
♦ Ct
♦ Iref.
= reference current for which the motor reaches a maximum thermal state of
100 % in stabilized mode (I ref. is adjustable expressed as a percentage of the rated
current In).
♦ Ipre
= current of load of the motor at the initial status.
♦ Imot
= real current of load of the motor at the t time:
I mot
=
I pos ² + K * I neg ²
In order to obtain a more realistic image of the thermal stress bore by the motor, the positive
sequence component of the current (representative of the torque motor) and the negative
sequence component with a weighting factor K (representative of the unbalance) are taken
into account.
The positive and negative sequence components are calculated from the I1 and I3 currents.
Before the trip (for a thermal state of 100 %), a thermal alarm is generated when the thermal
state reaches its alarm threshold, adjustable from 80 to 100 %.
18.1.2 Time-constant
The time-constant Ct used by the thermal image varies according to three modes depending
on the threshold IDem of start and locked rotor (see the paragraph dedicated to this function).
18.1.2.1 Mode of start (Imot > Idem starting threshold)
The starting threshold Idem is determined according to Iref..
The mode of start of the motor is noted as soon as Imot current becomes higher than the
adjustable starting threshold Idem.
During the starting period, heating is faster than in normal circumstances, because the motor
has not still reached its normal speed. The heating time-constant can be balanced and
decreased consequently.
In this case, CTE is multiplied by a constant FD (factor of start) lower than 1:
Starting time-constant Ct = FD * CTE.
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18.1.2.2 Normal operation (Imot < Idem - starting threshold)
The motor is considered in normal circumstances, as soon as Imot current is lower than the
starting threshold Idem.
In this case, the heating time-constant of CTE motor is not balanced:
Ct = CTE
18.1.2.3 Mode of cooling (Imot < 0.05 Idem starting threshold)
The motor is considered stopped as soon as Imot current becomes < 0.05 Idem . As soon a
motor is not fed any more, its speed quickly decreases and the time-constant increases
because of the less effectiveness of cooling system:
Cooling time-constant CTR = 1.0 up to 6.0 * CTE.
18.2 Description of the hot motor restarting inhibition function
When the motor reaches a temperature close to the thermal trip, a new start of the motor can
cause very quickly the thermal trip. To avoid this situation, it is possible to prohibit any new
start of the motor as long as its thermal state θ has not decreased below a specified
threshold.
This function trips one relay “INHIBITION OF START” which will be inserted in series in the ready
to start control chain of the motor.
It is recommended to use the change-over relay C which has a normally closed contact in
steady state condition:
- cold motor ( θ < set threshold): the chosen relay is unenergized (closed contact).
Start is authorized.
- hot motor ( θ > set threshold): the chosen relay is activated (open contact). Start is
prohibited.
18.3 Setting characteristics
CHARACTERISTICS
Values
CTE : Heating time-constant
4 up to 180 min
in step of 1min
1.0 up to 6.0 CTE
in step of 0.1
0 to 9
in step of 1
50 to 100 %
in step of 1%
Iref = 0.40 up to 1.30 In
in step of 0.01 In
CTR : Cooling time-constant
K : Negative sequence factor
FD : Factor of start
Iref : Thermal current of reference
Accuracy
Class 5
Class 5
Class 5
Thermal alarm threshold
80 up to 100 % θ thermal state
in step of 1%
Class 5
Motor hot starting thermal threshold inhibition
40 to 100 % θ thermal state
in step of 1%
Class 5
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18.4 Setting advises
Let us consider as an example the following data to protect an induction type motor:
♦ CT = 100/5 Amps - 5VA 5P15
♦ In Relay = 5 Amps
♦ Rated current of the motor = 90 Amps
♦ Motor load factor = 100%
♦ Starting current of the motor = 450 Amps (= 5 times In motor)
♦ Starting time of the motor = 4 s
♦ Heating thermal time-constant * = 20 min
♦ Cooling of the motor by fan at the end of shaft.
* motor maker’s data
Adaptation of the rated current of the motor to the relay:
The rated current of the motor must be adapted to:
♦ Current transformers (CT)
♦ The setting steps of the thermals reference current I ref.
♦ Motor load factor "Fc". If the load factor of the motor is lower than its rated power, the
“Fc" coefficient is not used (case of an oversized motor). If the motor must be used at
its rated power, "Fc" must be set between 1.05 and 1.07 (values corresponding to a
permanent overload from 5 to 7 % without reaching the thermal trip).This parameter
must be taken into account at the time of the setting calculation, and is not a setting
parameter of the relay.
Iref. = (In motor/CT) x "FC"
Calculation of the thermal threshold and parameters to be set on protection:
The trip threshold Iref. will be set at the following value: I ref. = (90/100)x1.07 = 0.963 corrected
by the setting step: 0.96.
The heating time-constant CTE will be set at the requested value: 20 min.
Taking into account the cooling mode, constant CTR will be set at twice the heating time
constant.
Calculation of the thermal inhibition threshold of restarting:
In order not to disturb operation, this threshold, if possible, must be set at 90% of the thermal
state calculated by the protection. In this case, the lack of trip of the motor during the hot
starting time is checked with the equation of the thermal image and according to the motor
characteristics:
t = CTE
⎛ I mot 2 − I pre 2 ⎞
⎟
∗ ln⎜
⎜I 2 − I ²⎟
ref ⎠
⎝ mot
With:
♦ t
= tripping time (in seconds) by the thermal function during the start
♦ CTE
= 1200 s (20min)
♦ Imot
= 5 (450A/90A)
♦ Iref.
= 1.07
♦ Ipre
=1
The result of 7.26 s, taking into account the motor starting time (4 s), enables us a setting of
90% for the thermal inhibition threshold of restarting.
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Weighting by the negative sequence:
The current transformers being of Class 5 P and the installation not being subject to
significant unbalanced currents, the weighting factor of the negative sequence will be set to
9. So unbalances lower than the operating threshold of the negative phase sequence unit
[46] will be taken into account in the calculation of the thermal image.
The factor of start will be set at 90%, thus balancing the heating time constant during the
phases of start.
In addition, the alarm threshold could be set on 95% and thus warns the operator before trip.
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18.5 Thermal heating curves (motor)
The following curve indicates the tripping time according to the initial preload current Ipre, for
a time-constant CTE = 10 min.
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18.6 Thermal cooling curve (motor)
The following curve indicates the necessary time for cooling from an initial thermal state with
no motor current flowing.
The curves correspond to a time-constant cooling CTR = 1 min.
For another value of time-constant, it is necessary to multiply the time indicated on the curve
by the value of the used time-constant in minutes.
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19. Too Long Start [48] and Locked Rotor Functions [51LR]
19.1 Description of the functions
The “too long start” function protects the motor if over current during start lasts more than
one adjustable time setting (representative of a normal start).
The start function of the motor is enabled when the current is above 5 % of IDem.
When the start is carried out normally, the currents (I1 or I3) become higher than the starting
threshold Idem during a specified time and then drop below IDem.
As IDem, is reached, a starting time delay is enabled.
If at the end of this time delay, the current is still higher than IDem, trip by the too long start
function is given.
The "locked rotor" function is put in service when a current above the starting threshold Idem
is measured out of the starting period. This function starts only three seconds after the end of
a starting period, that is to say that the measured currents (I1 or I3) becomes lower than the
starting threshold IDem.
.
19.2 Setting characteristics
CHARACTERISTICS
Values
Starting and locked rotor threshold (IDem)
Too long start time delay
Locked rotor time delay
1 up to 10 Iref.
in step of 0.1 Iref.
2 up to 200 s
in step of 1 s
0.2 up to 2 s
in step of 0.1 s
Accuracy
±5%
±5%
±5%
19.3 Setting advises
Let us consider as an example the following data in order to set this function:
♦ CT = 100/5 A - 5VA 5P15
♦ In Relays = 5 A
♦ Motor rated current = 90A
♦ Starting current of the motor = 450A (5 times In motor)
♦ Motor start in "direct" mode
♦ Starting time of the motor = 4 s
♦ Rotor stall withstand (cold) = 10 s.
Setting of the starting and locked rotor thresholds:
Taking into account the starting current which is equal to 5 times the rated current of the
motor, the starting threshold IDem will be set at 3 times the reference current Iref.. This setting
value will allow detecting a start independently of the value of the network voltage. In addition
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the locked rotor current of a running induction type motor being close to its starting current,
starting threshold IDem set at 3 times the reference current Iref. satisfies to the criterion of
detection of this risk.
Setting of the too long start time delay:
The time delay of too long start will be set with the value of 4 s. So if at the time of the start
the current of the motor is higher than I Dem during more than 4 s, protection will trip.
Setting of the locked rotor time delay:
For our application, the time delay, taking into account its operating threshold, will be set at 1
s. This value allows freeing from possible short time overloads during the operation of the
motor.
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20. Number of Starts Restriction Function [66]
20.1 Description of the function
This function is designed to avoid an excessive heating caused by too frequent starts. It
particularly avoids overheating of the fuses and starting system.
This function counts the number of starts carried out during a reference period Tnd.
In the event of number of start reached the same output relay that control the motor by the
hot starting thermal threshold inhibition is enabled.
The contact is held during one blocking period Tint, which must be set at a value higher (or
equal) than Tnd in order to allow a sufficient cooling of the motor after a sequence of starts.
The remaining number of authorized starts is indicated by protection (measurement menu of
the HMI).
20.2 Setting characteristics
CHARACTERISTICS
Values
Maximum numbers of starts during Tnd
Tnd: Reference period
Tint: Blocking period
1 up to 4
in step of 1
15 up to 60 min
in step of 1 min
15 up to 60 min
in step of 1 min
Accuracy
±5%
±5%
20.3 Setting advises
This function must be parameterized compared to the motor maker’s data. For example 2
starts per hour authorized:
♦ Number of starts = 2
♦ Tnd = 60 min
♦ Tint = 60 min
NOTE: The motor hot starting thermal threshold inhibition function is a feature designed to
complete the limitation of the number of starts for the supervision of hot motor.
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21. Phase to Phase [50] and Earth-Fault [51N] Short-Circuit
21.1 Description of the function
Phase over-current 50 function ensures the detection of the phase to phase short-circuits.
Maximum of zero-sequence current 51N function ensures the detection of the faults between
phase and earth.
In order to prevent trips by false earth-fault current during the phase detection of start of the
motor, the earth-fault protection function may temporarily be inhibited. This should
particularly be done if phases CTs are used for the calculation of the residual component
instead of a ring CT (risk of CT saturation during the starting time).
21.2 Setting characteristics
CHARACTERISTICS
Resetting Percentage
Response time of the instantaneous outputs
Overshoot
Time delay and phase short circuit threshold 50
Definite time delay
Phase threshold
Time delay and earth fault threshold 51N
Earth-fault threshold Inhibition during start time
Definite time delay
Earth threshold CTs connection
Earth threshold ICE ring CT* connection (6 to 48 A)
Values
94 ± 1.5 %
60 ms
< 55 ms
Setting
40 ms up to 3 s
in step of 0.01 S
3.0 up to 2.0 In
in step of 0.1 In
Setting
On/Off
40 ms up to 3 s
in step of 0.01 S
0.03 up to 0.40 In
in step of 0.01 In
0.03 up to 2.40 In
in step of 0.01 In
Accuracy
typical for I ≥ 2 Is
Accuracy
± 5 % or 20 ms
±5%
Accuracy
± 5 % or 20 ms
±5%
±5%
* CBCT 100/1 and use of BA800 for CBCT 1500/1
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21.3 Setting advises
21.4 Function [50]
Enabling or disabling this function depends, generally, of the breaking capacity of the control
unit of the motor:
♦ fuses contactor: setting out of service of the function [50]
(fuses must clear the short-circuits)
♦ circuit-breaker: setting in service of the function [50]
(CB having the breaking capacity to clear the short-circuit currents)
If the function [50] is enabled, its setting must consider the motor starting current. In order to
authorize the starts, the threshold [50] must be higher than the motor starting current. A
setting level of 40% above the starting current will usually fit.
Concerning the protection selectivity chain, the [50] short-circuits detection unit of a motor
protection relay is the downstream located function. So to isolate, as quickly as possible, the
faulty part of the network and not bring additional time constraint, the trip will be
instantaneous or a little bit time delayed.
Let us consider as an example the following data to protect an induction type motor:
♦ CT = 100/5 A - 5VA 5P15
♦ In Relay phase = 5 A
♦ ICE ring CT - T0 105.1
♦ In Relay earth = 0.2 A (earth nominal current for ring CT)
♦ Motor starting current = 450A
♦ Control unit of the motor = circuit-breaker.
♦ Capacitive current downstream protection = 0.8 A
The [50] trip threshold will be set at the following value: I>> = (450x1.4)/100=6.3 In.
The trip will be chosen "instantaneous".
21.4.1 Function [51N]
As a general rule, it is advised, according to the neutral system type of the electrical supply
network feeding the motors, to use this unit with measurement of the zero-sequence current
by ring CT. This method allows detection of a low current characterizing a resistive earthfault. The detection of the resistive earth faults will limit the costs of repair (rewinding could
be enough without requiring the replacement of the motor).
If the measurement of the earth fault current by a ring CT is not possible, the use of the
maximum of zero-sequence current unit fed by a residual connection of 3 CTs can be
considered. Possibly an inhibition during the start period will have to be examined or the
threshold will not be fixed below 0.15 to 0.2 In CT in order to avoid spurious trips.
There is a lower limit for the setting of the earth-fault unit threshold. The self capacitive
current of the protected feeder, feeding a fault to a nearby feeder, is likely to trip the
considered earth-fault unit inappropriately. As an indication, the capacitive current per
kilometre of cable, for 5-6 kV networks, is about 1 up to 2 Amps.
If the control unit of the motor is a circuit-breaker, as for the function [50], for the protection
selectivity chain, the earth faults unit detection [51N] of a motor protection relay is the
downstream located function. So to isolate the faulty part of the network as quickly as
possible and not to bring additional time constraint, the trip will be instantaneous. On the
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other hand, if the control unit is a fuses contactor, a minimal operating time of 0.25 s up to
0.5 s will have to be taken into account for the trip unit to keep it selective with the fuses blow
in the case of earth fault current evolving to two-phase fault.
The [51N] threshold of the earth-fault protection unit will be set at 1.5 times the capacitive
current suitable for the feeder:
Io > = 0.8 x 1.5 = 1.2A. Threshold to be set on the relay will be: 1.2A / 20 = 0.06
NOTE: 20 = coefficient taking account of the ring CT ratio, 100/1, and the nominal current of
the earth input, 0.2A. In case of use of CBCT 1500/1 and BA800 the coefficient is as well 20.
The control unit being a circuit-breaker, the trip will be chosen "instantaneous".
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22. Minimum of Load - Unpriming [37]
22.1 Description of the function
The detection of a current lower than an adjustable threshold allows carrying out a trip during
the pump unpriming or a rupture of mechanical drive.
The phase positive component of the current is used for this function. It is calculated from the
phase currents I1 and I3.
When the current becomes lower than the threshold, the trip is carried out at the end of a
user programmable time delay.
Clearance of the fault is noted when lack of current is detected (5 % I Dem) during at least 100
ms.
22.2 Setting characteristics
CHARACTERISTICS
Resetting Percentage
Minimum of load trip time delay
Values
Minimum of load threshold - I positive
106 %
0.05 up to 120 s
In step of: see *
0.10 up to 2.40 In
in step of 0.1 In
Accuracy
±1%
±5%
±5%
* from 0.05 to 0.99 s in step of 0.01 s, 1 s with 59.9 s in step of 0.1 s, 60 to 120 s in step of
1s
22.3 Setting advises
To detect a pump unpriming or a minimum of load, the threshold of the function [37] must be
compared to the current of the motor corrected by the setting step of the relay. A value lower
than 40% of the rated current of a motor generally indicates a no load run.
Let us consider as an example the following data to set this function:
♦ CT = 100/5 A
♦ In Relays = 5 A
♦ Motor rated current = 90A
♦ Pump unpriming current = 16A
The unpriming threshold will be set as follows: 16/100=0.16 In.
The setting value of the time delay will be chosen according to the process data and taking
account of the starting phase (time of no load of the motor before the priming of the pump).
NOTE: sometimes, the current criterion alone does not allow the detection of unpriming or of
minimum of load; it is then necessary to use a minimum of active power relay.
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23. Unbalance, Reversal and Loss of Phase [46]
23.1 Description of the function
The purpose of this function is to prevent the possible damage resulting from the
unbalances, reversal or loss of phases.
The detection of these unbalances is based on the measure of the negative sequence of the
current, calculated from the phase currents I1 and I3.
The characteristic of the phase negative sequence is a dependent specified time curve. This
allows on one hand the protection not to trip for small temporary unbalances, particularly at
the starting time period and on the other hand quickly trip during a real reversal or loss of
phase. The equation of the curves is (Iinv/In)² x t = Constant. These curves are defined at
100% of Iinv/In.
23.2 Setting characteristics
CHARACTERISTICS
Resetting Percentage
Dependent specified time curve (for Iinv = 100% Iinv/In)
Minimum time delay of trip
Negative sequence threshold Iinv
Values
94 %
1 up to 10 s
in step of 1 S
200 ms up to 10 s
in step 10 ms.
0.20 up to 0.80 In
in step of 0.1 In
Accuracy
± 1%
±5%
±5%
±5%
23.3 Setting advises
To ensure the detection and the clearance of single-phase current or of resistive two-phase
faults, a setting of 20 % for the [46] function (compared to the rated current of the motor
possibly corrected by the setting step of the relay) allows the detection of a phase loss.
A curve set at 2 s will allow the correct protection of the motor while avoiding spurious trips
during start.
The minimum setting of the time delay of trip will have to allow the fuses* to eliminate all the
heavy unbalanced faults before action of the associated contactor. A setting of 0.5 s will
generally meet this condition.
* fuses contactor cases
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23.4 Negative sequence current trip curves
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24. Load-Shedding with External Input and High Speed Restarting
24.1 Description of the function
In the event of network fault such as a strong voltage or frequency drop, a load-shedding of
the motor may be carried out by using the binary input "load-shedding".
The trip is carried out at the end of an adjustable time delay.
If the external order disappears before the end of the time delay, the relay does not send a
trip order and allows a reacceleration during a delay corresponding to a start.
24.2 Setting characteristics
CHARACTERISTICS
Load-shedding time delay
Values
60 ms up to 120 s
Accuracy
±5%
* from 0.06 to 2.99 s in step of 0.01 s, 3 s with 29.9 s in step of 0.1 s, 30 to 120 s in step of
1s
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25. Inputs – Outputs Relays Configuration & LED Indicators
Functions described hereafter are only available with PC setting software.
25.1 Digital inputs
A list of functions can be assigned to the available digital inputs (1 group of 4 inputs or 2
groups of 4 inputs, according to relay or option).
The setting software checks that an input is only affected to only one function and that the
enabled functions have the necessary inputs for proper operation.
For instance, the remote control function requires the assignment of the four* following
inputs:
♦ Interlock O/O input: closed position of the circuit-breaker
♦ Interlock C/O Input: open position of the circuit-breaker
♦ Local Input: operation of the cubicle in local mode
♦ Remote Input: operation of the cubicle in remote mode.
* since the software version V2.20 of the NP800 relays the number of input(s) dedicated to
the supervision of the local/remote mode are user-definable (1 or 2 DI). Two inputs are
necessary for the management of the Local/Remote discrepancy.
It is possible to select the operating mode of each input:
♦ Positive true-data: the input is enabled when polarized
♦ Negative true-data: the input is enabled when not polarized. This mode is to be used
for operation in the event of loss of a connection wire.
Level 0: < 10V range of auxiliary supply voltage from 19 up to 70 VDC
< 33V range of auxiliary supply voltage from 85 up to 255 VDC
Level 1: > 20V range of auxiliary supply voltage from 19 up to 70 VDC
> 37V range of auxiliary supply voltage from 85 up to 255 VDC
Burden: < 20 mA
25.2 Outputs relays and function [86]
It is possible to affect one or several of the 7 output relays to each protection function and to
select its operating mode:
♦ Output contact latched after the loss of the fault, function [86]. Resetting is carried out
by the activation of an input (digital or by the communication) dedicated to this
functionality. Since the software version V2.20 of the NP800 relays the reset is
available by the local HMI.
♦ The output contact drops down, if the fault disappeared at the end of the pulse order.
NOTE: when a “trip by the remote control” relay is used, as a general rule, it must be the
same relay used for the trip of the protection functions.
25.3 LED Indicators
Protection is fitted with 4 indicators LEDs (yellow) user programmable and assignable to:
♦ a trip by a protection function. This status remains stored, until the acknowledgement
of the events by the local HMI or by the PC setting software
♦ a trip by a generic function (storage status)
♦ a trip or a closing by remote control (non stored status)
♦ all type of trip
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♦ alarms status: maximum number of trips, circuit-breaker failure; no complementarity
O/O - C/O, local/remote discrepancy, circuit-breaker fail (non stored status)
♦ The status of the binary inputs: O/O - C/O, Local - Remote (non stored status)
♦ Operating mode: setting group 2, remote mode (non stored status)
♦ Miscellaneous: PC communication, detection of network messages (non stored
status)
It is possible to choose an operation with a fixed lit or blinking indicator.
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26. Circuit-Breaker Maintenance
This function monitors the circuit-breaker in order to ease its maintenance. Sum of cut off
square amps as well as number of “open/close” cycles are counted. Please consult the
circuit breaker manufacturer instruction manual in order to use the data’s.
The cumulative of the break current kA² is validated when the following conditions are met:
- trip ordered by protection.
- disappearance of the current during the tripping time period. Period corresponding to
the minimum trip pulse of the output unit which is added a fixed time delay of 100ms.
Further this period, the cumulative of the current is not carried out.
The number of operations of the circuit breaker is incremented when:
- protection orders a trip and that the conditions described above are observed.
- the remote control mode is enabled and there is one remote opening order of the
circuit breaker.
In the event of use of the relay in link with existing equipment, the setting software allows
preconfigured values.
CHARACTERISTICS
kA² cut off alarm (on trip)
Circuit breaker number of operations
Range
1 à 64000000
1 à 10000
Accuracy
± 10%
26.1 Trip Circuit Supervision of the circuit-breaker [74TC]
This function, available since the software version V2.10 of the NP800 relays, allows the
supervision of the trip circuit of the CB.
In the event of lack of continuity, the alarm “COIL CIRCUIT BREAKER" » is generating. The
function is inhibited during the action of the output relay(s) assign for the trip of the circuitbreaker. This function implies the use of a group of 4 digital inputs. [74TC] function available
for all the NP800 relays.
The use of the PC software is required for the configuration of this function. For the
assignment of the digital input, the trip relay(s), C-D-G prefer, and eventually the alarm relay.
The 3 following application diagram cover the usual case of circuit-breakers control.
Diagram 74TC-1:
The trip coil terminals of the circuit breaker are available. In this case only one o/o interlock
allows the supervision of the trip circuit of the CB whatever its position. (Close or Open) The
polarizing current of the DI throughout the coil is about 10mA for the 19-70 VDC auxiliary
voltage and about 4mA for the 85-255 VDC auxiliary range.
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+ VDC
52 o/o
NP800
C-D-G
DI
52 - Trip coil
- VDC
Diagram 74TC-1
Diagram 74TC-2:
The trip coil terminals of the circuit breaker are not available. In this case only one o/o
interlock, connected in serial with the trip coil, and one f/0 interlock allows the complete
supervision of the trip circuit of the CB closed and partially CB open. The polarizing current of
the DI throughout the coil is about 10mA for the 19-70 VDC auxiliary voltage and about 4mA
for the 85-255 VDC auxiliary range.
The use of one additional* resistor is necessary for limiting the current during the activation
and in case of latch of the output relays (C-D-G).
* not supply with the NP800 relay
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NP800 range
Date : 08/2006
Sheet : 82
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+ VDC
NP800
C-D-G
52 o/o
DI
52 f/o
R. add.
52 - Trip coil
- VDC
Diagram 74TC-2
Diagram 74TC-3:
The trip coil terminals of the circuit breaker are not available, however the o/o interlock
terminals connected in serial with the coil are available. In this case the o/o interlock and one
o/f interlock allows the complete supervision of the trip circuit of the CB whatever its position.
(Close or Open) The polarizing current of the DI throughout the coil is about 10mA for the 1970 VDC auxiliary voltage and about 4mA for the 85-255 VDC auxiliary range.
The use of one additional* resistor is necessary for limiting the current during the activation
and in case of latch of the output relays (C-D-G).
* not supply with the NP800 relay
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NP800 range
Date : 08/2006
Sheet : 83
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+ VDC
NP800
C-D-G
DI
52 f/o
R. add.
52 - Trip coil
- VDC
Diagram 74TC-3
26.1.1 Calculation of the additional resistor
The calculation according the application diagram take account of the minimum current value
flowing through the digital input. This minimum value is related to the voltage polarisation of
the digital input and the auxiliary voltage supply of the relay.
Drawing 74TC2:
The ohmic value of the additional resistance is defined by the following equation:
R. add. < (0.8 * Vdc- Vmin) / Imin
With:
Vdc: value of the auxiliary voltage
Vmin: minimum internal voltage value necessary for the operation of the digital input
Imin: minimum current value necessary for the operation of the digital input
Auxiliary voltage supply range of the NP 800 relays
19 – 70 Vdc
85 – 255 Vdc
R. add. < (0,8 * Vdc- 12)/ 0,01 R. add. < (0,8 * Vdc- 33) / 0,004
The power of the additional resistor (in Watt) is defined as follow:
Pr > 2 * (1.2 * Vdc)² / R
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NP800 range
Date : 08/2006
Sheet : 84
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Drawing 74TC3:
The ohmic value of the additional resistance is defined by the following equation:
R.add. < (0.8 * Vdc- Vmin)/ Imin – Rcoil
With:
Vdc: value of the auxiliary voltage
Vmin: minimum internal voltage value necessary for the operation of the digital input
Imin: minimum current value necessary for the operation of the digital input
Rcoil: resistance value of the trip coil
Auxiliary voltage supply range of the NP 800 relays
19 – 70 Vdc
85 – 255 Vdc
R. add. < [(0,8 * Vdc- 12) / 0,01] – Rcoil
R. add. < [(0,8 * Vcc- 33) / 0,004] – Rcoil
The power of the additional resistor (in Watt) is defined as follow:
Pr > 2 * (1.2 * Vdc)² / (R + Rcoil)
Remarks:
In case of presence of auxiliary relays for anti-pumping in the trip circuit, they will have to be
taken into account during the calculation of the ohmic value of the additional resistor.
For the two applications we assume that the maximum variation of the auxiliary supply is
about +/- 20%.
26.1.2 Operating mode of the digital input
The fault detection of the circuit-breaker trip circuit carried being out by the passage of level
1 to level 0 of the digital input, the operating mode of this input will have to be configured,
thanks to the configuration software, as a “ positive true-data mode”.
26.1.3 Wiring of the trip circuit
If several protective relays are wired in the trip circuit of the circuit-breaker, the [74TC]
function will have to be enabled only on only one of these relays. To avoid spurious alarms,
this one will have to receive thanks of one of its generic inputs the trip order from the other
relays. This order will have to be switch to the trip relay (C-D-G) of the circuit-breaker.
26.1.4 Characteristics of the function [74TC]
CHARACTERISTICS
Values
Response time (trip coil circuit faulty)
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200 ms - fixed
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NP800 range
Date : 08/2006
Sheet : 85
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26.2 Circuit-breaker Failure [50BF]
This function, available since the software version V2.10 of the NP800 relays, checks the
opening of the poles of the circuit-breaker after a trip order given by protection. (order from
protective functions or via the communication network )
The function monitors the opening time of the circuit-breaker. Relay checks that the phase
and/or earth-fault currents are lower than a user programmable threshold at the end of the
circuit-breaker failure time delay.
If not, a "CIRCUIT-BREAKER FAILURE" alarm is generated.
The circuit-breaker failure function is available on the following relays: NPI800, NPID800,
NPIH800, NPIHD800 and NPM800.
The use of the PC software is required for the configuration of this function. For the
assignment of the digital input, the trip relay(s) and eventually the alarm relay.
CHARACTERISTICS
Values
Circuit-breaker failure threshold*
[50BF] [50NBF]
Circuit-breaker failure time delay (tBF)
5 to 30 % InPh in step of 1%
0.5 to 3 % In0 in step of 1%
60 to 500 ms in step of 10 ms
*common adjustment phase and earth, in the ratio, for NPI(D)800 and NPM800
Remarks:
- the setting adjustment of failure acts implicitly on the measured values of the
protection. (« noises threshold»)
The three [50BF] drawings describe the function:
The curve 1 show a normal operation of the circuit breaker with a trip order followed by a
measurement of the current, at the end of the time delay tBF, lower than the circuit-breaker
failure threshold. (no current flowing)
The curve 2 show an abnormal operation of the circuit breaker with a trip order followed by
a measurement of the current, at the end of the time delay tBF, not lower than the circuitbreaker failure threshold. (current still flowing)
The curve 3 show an abnormal operation of the circuit breaker with a trip order not followed
by the opening of the poles of the circuit-breaker. (current still flowing)
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NP800 range
Date : 08/2006
Sheet : 86
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Trip pulse
[50BF] Time-delay (tBF)
Current still flowing ( < [50BF] thresold)
1
Current still flowing ( > [50BF] thresold)
2
Circuit-breaker failure
No opening of the circuit-breaker
3
Drawing [50BF]
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NP800 range
Date : 08/2006
Sheet : 87
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27. Logical Selectivity Function
27.1 Description of the function
The logical selectivity function is used when the number of relays becomes too significant to
allow use of time selectivity. In a radial network, during the fault time, upstream protections of
the faulty part are solicited. On the other hand, all downstream protections are not. Due to
this fact, it is easy to locate without delay the faulty part, and define without ambiguity the
only circuit-breaker to be ordered.
Each solicited protection for the phase and earth-fault protection functions must:
♦ As soon as a threshold of these functions is reached and using an output relay in
"instantaneous mode", activate* the selectivity logical input of the immediate
upstream protection in order to add a time lag to its tripping time delay.
♦ Give a trip order to its associated circuit-breaker; the trip occurs if no time lag order is
received from the immediate downstream protection.
* using a pilot wire connection
Thus, the downstream and closest to the fault protection trips first. The upstream relays act
as back-up of downstream protection.
In conclusion this function allows to reduce the selectivity step-times between various
protections and to set all the protections with a short operating time.
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NP800 range
Date : 08/2006
Sheet : 88
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Issue : d
I
X
0.1s
0.3s
t1
ta(sl)
El(sl)
t2
2
B
X
Instantaneous
output unit
I
t1
0.1s
1
A
I= I fault
El(sl) = logical input dedicated to the logical selectivity function
1= tripping time = t1
2= tripping time if El(sl) = 1 => t2= t1+ ta(sl)
2= tripping time if El(sl) = 0 => t2= t1
t1+ta(2)
0.4s
t1(1)
0.1s
0.1s
"A" FAULT
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t1(2)
"B" FAULT
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NP800 range
Date : 08/2006
Sheet : 89
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27.2 Operating mode of the logical selectivity input
Positive true-data mode
The function is enabled by a level 1.
In this case, loss of pilot wire forbids activation of the function. Nevertheless protection of the
network is maintained by the relay.
Negative true-data mode
The function is enabled by a level 0.
In this case, loss of pilot wire is interpreted like a permanent request for selectivity.
Nevertheless protection of the network is maintained by the relay at the end of the selectivity
time delay.
27.3 Setting characteristics
CHARACTERISTICS
Accuracy
Step
Very high-set phase [50] logical selectivity time 60 ms up to 3 s
delay
Low-set and high-set [51-1] [51-2] phase logical 60 ms up to 3 s
selectivity time delay
High-set earth [50N] logical selectivity time delay
60 ms up to 3 s
± 2 % or 20 ms
10 ms
± 2 % or 20 ms
10 ms
± 2 % or 20 ms
10 ms
Low-set earth [51N] logical selectivity time delay
± 2 % or 20 ms
10 ms
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Values
60 ms up to 3 s
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Date : 08/2006
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28. Remote Control Function
The remote control function allows, according to the Local and Remote inputs, to send
closing and tripping order with the communication network:
♦ Deliberate remote order of trip
♦ Deliberate remote order of closing
♦ Load-shedding with level of priority
♦ Reconnection.
Operation:
In local mode, the remote orders are inhibited.
This function uses 2 complementary binaries inputs: LOCAL / REMOTE. In the event of non
complementarity of these 2 inputs a DISCREPANCY LOCAL / REMOTE alarm is generated and
the local mode is forced.
An output relay may be assigned to this alarm.
The operator is warned of the switch to remote mode by a "REMOTE MODE " message on the
display. An event “REMOTE MODE " is generated at change of mode.
Since the software version V2.20 of the NP800 relays the number of input(s), 1 or 2 DI, is
configurable for the management of the local/remote mode. In the case of use of only one
input, status 1 corresponds to remote and status 0 to local.
NB: for the management with 2 inputs if the status is 0 for the 2 inputs, the function is
considered in Local mode.
28.1 Trip by remote control
When protection receives a trip order by remote control, the following actions are carried out:
♦ Activation of the output relay(s) associate(d) to the remote control (A-B-C-D-E-F)
♦ Display of the message: "TRIP BY REMOTE CONTROL" on LCD
♦ Generation of an event: " TRIP BY REMOTE CONTROL "
This order is taken into account except in the event of circuit-breaker failure.
28.2 Closing by remote control
When protection receives a close order by remote control, the following actions are carried
out:
♦ Activation of the output relay(s) associate(d) with the remote control (A-B-C-D-E-F)
♦ Display of the message: "CLOSING BY REMOTE CONTROL " on LCD
♦ Generation of an event: "CLOSING BY REMOTE CONTROL"
This order is taken into account except in the event of circuit-breaker failure.
28.3 Load-shedding by priority level
This order is carried out if the load-shedding level is higher or equal to the level, between 1
and 5, programmed in protection. No load shedding is available in case of level 6 of priority
corresponding to a prioritary feeder.
If a protection receives a load-shedding order whereas the circuit-breaker is already open,
this order will be ignored as well as the reconnection order which will follow.
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NP800 range
Date : 08/2006
Sheet : 91
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Issue : d
28.4 Reconnection
This order is carried out independently of the levels, and only if protection has previously
received an order of load-shedding. The reclose order is given at the end of the adjustable
time delay of reconnection separately for each relay.
In the event of switch to local mode, the reconnection will not be carried out.
CHARACTERISTICS
Time delay before reclosing
Pulse of trip
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Values
1 up to 120 s
in step of 1 s
100 up to 500 ms
in step of 10 ms
Application Guide
NP800 range
Accuracy
± 2 % or 20 ms
Date : 08/2006
Sheet : 92
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29. Programmable Generic Functions
Up to 8 programmable generic functions may be configured according to the following
parameters:
♦ Setting in and out of order
♦ Operating time delay
♦ Identification of the function with a maximum wording length of 14 characters
♦ Assignment of the function to a binary input
♦ Assignment of one or several output relay.
Activation of an input starts an adjustable time delay. At the end of this time delay a trip order
is given to the programmed output relays.
A dated event indicating the name of the function is automatically added to the event log.
Since the software version V2.20 of the NP800 relays the generic inputs can be configured
as “report” mode of dated event.
CHARACTERISTICS
Processing time
Operating time delay
Values
Accuracy
15 ms
40 ms up to 300 s in step of 10 ms
typical
± 2 % or 20 ms
Application example: for a power transformer, treatment of the Buchholz and thermostat
contacts in order to record and date the events and to obtain a redundancy of the alarm and
trip circuits of these “direct” protections.
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Application Guide
NP800 range
Date : 08/2006
Sheet : 93
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Issue : d
30. Relay Parameters
30.1 Setting groups 1 and 2
NP800 relays are fitted with two selectable parameters groups for the following functions:
NPI800
NPID800 NPIH800 NPIHD800 NPM800 NPU800 NPUH800
[37/I]
X
[46]
X
X
X
[46BC]
X
X
[48]
X
[49]
X
X
X
[51-1][51-2]
X
X
[51LR]
X
[50]
X
X
X
[51N]
X
X
X
X
X
[50N]
X
X
X
X
[66]
X
[67]
X
[67N]
X
X
[27]
X
[27P]
X
[59]
X
[59N]
X
[81.U]
X
[81.O]
X
Logical
X
X
X
X
selectivity
The request for use of the setting group 2 is realized by activation of:
♦ Binary Input: Set 2
♦ Remote communication network
♦ Software PC (during commissioning)
By default Set 1 is active.
It is possible to read the active table by:
♦ Local HMI: measurements menu
♦ PC Setting software (tabs Set 1 and Set 2 of functions)
♦ Remote communication network
30.2 Priorities management
Priority is given to use of the setting group 2, whether this request is done from the binary
input or from a communication network order.
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NP800 range
Date : 08/2006
Sheet : 94
Print : 09/03/2007
Issue : d
31. Events
31.1 Storage/acknowledgement
When protection gives a trip order, an event is automatically generated. The event function
can memorize the last 250 events, as well in case of auxiliary supply loss (200 in this case).
The oldest events are removed from the memory of the protection. (FIFO stack)
It is possible to program a LED to indicate the presence of an event to be acknowledged.
Acknowledgement is carried out locally by the successive action on the CLEAR and ENTER
keys of the relay, or by the setting software or by the communication channel.
31.2 Contents of an internal event
♦
♦
♦
♦
♦
Type of event
Appear/Disappear (Appear only in reading simplified mode)
Time-stamping in step of 10 ms
Electrical measures at tripping
Active setting group
31.3 Events modes management
Two modes of management of the events are provided in order to allow either a simplified
management, or a more detailed analysis of the faults. Programming of the mode can only
be done from the OPERATING menu of the PC software.
♦ Simplified mode:
only appearance of tripping or alarm events is memorized. Use
of this mode is advised if the operator acknowledges the events by the local HMI
♦ Complete mode:
Tripping, instantaneous and signalling events, either at
appearance or disappearance are memorized.
This mode is particularly useful during commissioning of the equipment or when
protection is connected to a SCADA for time-tagged log detailing its operation.
31.4 Time-stamping
At the power on time, the protection is set in relative time mode. The reference of time is
maintained with the clock time of the internal quartz of the protection.
The time is maintained during at least 72h in case of auxiliary supply loss.
After having carried out a setting time of protection by the commissioning PC or by the
communication network, Protection passes in non synchronous time mode.
When time messages are sent in an interval lower than one minute, the protection is in
synchronous time mode, allowing a time-stamping of the events with accuracy better or
equal than 10 ms.
31.5 Characteristics
CHARACTERISTICS
Relative time mode
Non synchronous time mode
Synchronous time mode
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Accuracy
< 10 s/day
< 10 s/day
≤ 10 ms
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NP800 range
Date : 08/2006
Sheet : 95
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32. Disturbance recording
The disturbance recording function is able to memorize 4 records, each of 52 cycles.
Pre-time is user programmable.
Format is COMTRADE binary format. It is possible to read the disturbance recording files by
the MODBUS ® communication network.
The PC setting software allows the analysis of these disturbance recordings: transfer,
display, saving, printing, measurement of various times and instantaneous or rms values...
It is also possible to carry out a manual trigger of disturbance recording, by the PC setting
software, a dedicated input or by a network order.
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Application Guide
NP800 range
Date : 08/2006
Sheet : 96
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Issue : d
33. Operating parameters
Some of the setting parameters of the relays are operating parameters.
The general parameters, according the type of the relay, are used by the entire functions of
the protection:
♦ Choice of the language use for the local HMI
♦ Customisation of the parameters file (sub-station and feeder identification)
♦ Phase and earth CTs rated value (InP)
♦ VTs rated value (UnP and configuration of Uns)
♦ Voltage operating mode (phase to neutral or phase to phase)
♦ Number of voltage(s) monitored
♦ Management of the events (simplified or with details)
♦ Instantaneous trips time delays
♦ Integration time period for the calculation of the average value of powers, currents or
voltages
♦ Minimal pulse time of trip
♦ Operating mode of the logical inputs (positive or negative true-data )
♦ The number of input(s) required for the Local/Remote management
♦ Operating mode of the output relays (pulse or maintained)
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Application Guide
NP800 range
Date : 08/2006
Sheet : 97
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Issue : d
34. Communication
Protection can be fitted with an optional RS485 communication interface. This function is
available on the back terminal block of the protection. It is independent of the front RS232
communication.
The communications protocols available are as follows:
♦ MODBUS ®
♦ IEC 870-5-103 (please consult us)
The necessary data's for the parameter of the communications are as follow:
♦ Slave Number
♦ Transmission Mode of the characters
♦ Transmission Speed in Bauds
♦ Transmission Format
CHARACTERISTICS
Slave Number
Transmission Speed
ASCII Format
Binary format
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Values
1 to 255
300, 600, 1200, 1800, 2400, 4800,9600, 19200, 38400, 57600 and
115200 bauds
8 bits without parity, 2 stops
8 bits without parity, 1 stop
8 bits even parity, 1 stop
8 bits odd parity, 1 stop
7 bits even parity, 1 stop
7 bits even parity, 2 stops
7 bits odd parity, 1 stop
7 bits odd parity, 2 stops
7 bits parity forced to 0, 2 stops
7 bits parity forced to 1, 2 stops
8 bits without parity, 2 stops
8 bits without parity, 1 stop
8 bits even parity, 1 stop
8 bits odd parity, 1 stop
Application Guide
NP800 range
Date : 08/2006
Sheet : 98
Print : 09/03/2007
Issue : d