Special Requirements
of IEEE C37.013 for
Generator Circuit Breaker
Applications
November 20, 2009
Schutzvermerk / ©Copyright-Vermerk
Siemens AG 2009
Sector Energy, Business Unit Medium Voltage
Generator Circuit Breaker Applications
What is different about generator
circuit breakers?
ƒ Applicable standards
ƒ Special considerations
ƒ Vacuum versus SF6 technology
ƒ Questions.
© Siemens AG 2009
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Generator and Distribution Circuit Breakers
Generator circuit breaker
Distribution circuit breaker
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Circuit Breakers for Distribution
Requirements
Standards:
ƒ IEEE C37.04
ƒ IEEE C37.09
ƒ IEEE C37.10
Rating structure for HV circuit breakers
Tests for HV circuit breakers
Application guide for HV circuit breakers.
ƒ X/R ratio:
17 (60 Hz).
ƒ Time constant of dc decay:
45 ms.
ƒ
ƒ
ƒ
ƒ
TRV typical values (15 kV, class S1 cable):
Peak voltage
(uc) = 25.7 kV
Time-to-peak
(t3) = 66 µs
RRRV
0.39 kV/µs.
ƒ Duty cycle:
Folie 4
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O – t’ – CO – t – CO
t’ = 0.3 s for reclosing / 15 s for non-reclosing
© Siemens AG 2009
t = 3 minutes.
Sector Energy, Business Unit Medium Voltage
Circuit Breakers for Generation
Requirements
Standards:
ƒ IEEE C37.013
Generator circuit breaker.
ƒ X/R ratio:
50 (60 Hz).
ƒ Time constant of dc decay:
133 ms.
ƒ
ƒ
ƒ
ƒ
TRV typical values (15 kV, 100 MVA machine):
Peak voltage
(E2) = 1.84 V = 1.84 x 15.0 = 27.6 kV
Time-to-peak
(T2) = 0.62 V = 0.62 x 15.0 = 9.3 µs
RRRV
3.5 kV/µs.
ƒ Duty cycle:
CO – 30 min – CO.
© Siemens AG 2009
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Notes on TRV Representation
IEEEC37.04 for distribution circuit
breakers expresses TRV in terms
harmonized with IEC with peak voltage
uc, and
time-to-peak t3.
IEEE C37.013 still uses old TRV
expressions with peak voltage E2 and
time-to-peak T2. Peak voltage is not
changed, but t3 is approximately 0.88 x
T2.
The physics are not changed, just the
representation.
© Siemens AG 2009
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IEEE C37.04-1999 Scope
IEEE Standard Rating Structure for AC High-Voltage Circuit Breakers
1. Scope
This standard establishes a symmetrical current rating structure and construction
requirements for all indoor and outdoor types of ac high-voltage circuit breakers
rated above 1000 V. It is only applicable to three-pole circuit breakers used in
three-phase systems and single-pole circuit breakers used in single-phase
systems.
This standard does not cover circuit breakers used at frequencies other than
50 Hz or 60 Hz, or generator circuit breakers that are covered in IEEE
Standard C37.013-1997.
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IEEE C37.013-1997 Scope
IEEE Standard for AC High-Voltage Generator Circuit Breakers Rated on a
Symmetrical Current Basis
1. Scope
This standard applies to all ac high-voltage generator circuit breakers rated on a
symmetrical current basis that are installed between the generator and the
transformer terminals...
Note: Since no other national or international standard on generator circuit
breakers exists, this standard is used worldwide.
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IEEE C37.013 – the International Standard
for Generator Circuit Breakers
IEEE C37.013 Revision PAR (Project)
ƒ PAR approved by IEEE-SA
Standards Board, March, 2009
ƒ Joint development with IEC SC 17A
(HV Switchgear and Controlgear)
ƒ IEEE WG chair is convenor (WG chair) of
IEC working group.
IEC has no standard for a generator circuit breaker.
The IEEE and IEC intent has been that IEEE
C37.013 would be the global standard.
IEC SC 17A WG 52
ƒ WG scope: Joint IEC/IEEE revision of
IEEE C37.013: IEEE Standard for AC HighVoltage Generator Circuit Breakers Rated on a
Symmetrical Current Basis
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X/R Ratio Determines %dc Component
X/R = 17, τ = 45 ms
X/R = 50, τ = 133 ms
%dc vs Contact Part for X/R = 17 and X/R = 50
120.0
%dc Component
100.0
80.0
60.0
40.0
20.0
0.0
0
5
10
15 20
25
30
35
40
45
50 55
60
Contact Part tim e (m s)
65
70
75
80 85
90
95 100
X/R = 17
X/R = 50
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X/R Ratio Effect on Asymmetrical Interrupting
3.00
Instantaneous (total) current
2.50
S-factor (C37.04-1979)
dc component
dc component (in decimal form)
(multiply by 100 for %dc component)
(C37.04-1999)
Current (Isc = 1.00)
2.00
1.50
1.00
0.50
0.00
-0.50
-1.00
-1.50
Symmetrical current (ac component)
3600
3420
3240
3060
2880
2700
2520
2340
2160
1980
1800
1620
1440
1260
1080
900
720
540
360
180
0
-2.00
Time (in degrees)
© Siemens AG 2009
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X/R Ratio Effect on Asymmetrical Interrupting
S=
I total
I symmetrical
= 1 + 2(%dc / 100)
S factor (from IEEE C37.04-1979)
Ratio of rms asymmetrical current to rms symmetrical current
Assume contact part time of 55 ms, and 50 kA symmetrical current
X/R = 17
%dc = 29.5
S = 1.084
I = 54.2 kA
X/R = 50
%dc = 66.1
S = 1.369
I = 68.5 kA
over 26% higher
© Siemens AG 2009
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Short-Circuit Currents
Consider system shown:
ƒ Transformer
ƒ 1,000 A full load (self-cooled)
ƒ impedance = 10%
ƒ Generator
ƒ 1,000 A full load
ƒ Xd’’ (subtransient reactance) = 20%
ƒ For fault at F2, circuit breaker sees transformer
fault current, roughly 1,000 A / 0.10 = 10 kA
ƒ For fault at F1, circuit breaker sees generator
fault current, roughly 1,000 A / 0.20 = 5 kA
F1
F2
G
Note:
Fault current for generator
source fault is only about
50% of fault current for
system (transformer)
source fault
© Siemens AG 2009
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Generator Circuit Breaker Ratings
Characteristic
Unit
Drawout
(Metal-Clad)
FixedMounted
Maximum voltage
kV
15.0
17.5
Dielectric 60 Hz / BIL
kV/kV
38 / 95
50 / 110
Short-circuit current
ƒ Transformer source
ƒ Generator source
kA
kA
40 / 63
20 / 31.5
50 / 63 / 72
25 / 31.5 / 36
%dc component
%
73 / 61
75 / 65 / 65
Delayed current zero*
ms
40 / 30
30 / 30 / 30
TRV parameters
ƒ Peak voltage (1.84 V)
ƒ RRRV transformer source
ƒ RRRV generator source
kV
kV/µs
kV/µs
27.6
3.5 / 4.5
1.6 / 1.8
32.2
4.5 / 4.5 / 4.5
1.4 / 1.8 / 1.8
* Higher values may be available
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© Siemens AG 2009
Sector Energy, Business Unit Medium Voltage
Generator Circuit Breakers
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Generator Circuit Breakers
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Out-of-Phase Switching
Circuit Breakers for Standard Applications:
ƒ IEEE C37.04 (clause 5.12):
ƒ Out-of-phase switching is optional, not required for general purpose circuit
breakers
ƒ If a rating is assigned, the preferred rating is 25% of the rated symmetrical
interrupting rating, with recovery voltage of (250% rated voltage / 1.732).
ƒ Therefore, out-of-phase ratings are not typically assigned to general purpose
circuit breakers rated per IEEE C37.04 and tested to IEEE C37.09.
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Out-of-Phase Switching
Circuit Breakers for Generator Switching Applications:
ƒ IEEE C37.013 (clause 6.2.9):
ƒ Out-of-phase switching is optional, not required for generator circuit breakers
ƒ If a rating is assigned, the assigned rating is shall be 50% of the rated
symmetrical interrupting rating (transformer or system source).
ƒ Out-of-phase switching recovery voltage values are based on a maximum
out-of-phase condition of 90 degrees between generator and system. This is
reasonable as more extreme angles would result in damage to the machine.
ƒ The likelihood of out-of-phase switching is influenced by generator inertia, i.e.,
low-inertia machines are more likely to be subject to out-of-phase switching
conditions.
ƒ Generator circuit breakers should have an assigned out-of-phase switching
rating.
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Other Differences
Reclosing:
ƒ Reclosing duty not required for generator circuit breakers.
ƒ Short-time current duration:
ƒ Normal circuit breakers
ƒ 3 seconds (metal-clad switchgear = 2 seconds)
ƒ Generator circuit breakers
ƒ 1.0 second (typically test to 3 seconds).
ƒ Closing & latching rating:
ƒ Normal circuit breakers
ƒ Peak current 260% of symmetrical short-circuit (60 Hz)
ƒ With X/R = 17, “real” peak is 259.3%
ƒ Generator circuit breakers
ƒ Peak current 274% of symmetrical short-circuit (60 Hz)
ƒ With X/R = 50, “real” peak is 274.2%.
© Siemens AG 2009
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160
150
140
130
120
110
100
90
80
70
60
50
40
30
20
10
0
Delayed Current Zero Example – C37.013
0.500
0.000
-0.500
Current (unitized)
-1.000
-1.500
-2.000
-2.500
-3.000
-3.500
-4.000
Time (ms)
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Delayed Zero Test Example
20.6 ms
30.0 ms
40.1 ms
57.7 ms
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Generator Circuit Breaker Technologies
Vacuum
ƒ Well-suited to smaller units
(up to 6,000 A or so)
SF6
ƒ Only option for very large units
ƒ
ƒ Most economic for small units
ƒ VERY expensive
ƒ Derived from proven distribution unit
operators and interrupters
ƒ High experience-base
ƒ Unlike distribution products
ƒ Very low arc voltage (20 - 50 V)
ƒ Little affect on X/R ratio
ƒ Lower arc voltage = less arc energy =
lower contact erosion
ƒ SF6 low arc voltage (several 100 V)
ƒ Somewhat higher impact on X/R ratio
ƒ Higher arc voltage = higher arc energy =
greater contact erosion
ƒ Lower experience-base
ƒ Extremely rapid recovery of dielectric
ƒ Less able to cope with high TRV levels
strength between contacts after
interruption – good for extreme TRV levels
© Siemens AG 2009
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