Type HSDI – 3
Voice Frequency
Intertripping Equipment
Features
● High speed digital intertripping
with very high security
● Single channel bi-directional
equipment with option of two
separate intertrip commands
● British Approvals Board for
Telecommunications (BABT)
approved 600 and 1200 baud
modem options using
internationally recognised CCITT
signalling frequencies
● Alarms for communication failure
and scheme faults
● LED indication of trips set/received
and test and alarm status
● 20 user selectable operating codes
● Timing test monitor sockets
● Auxiliary ports for additional voice
frequency equipment
● Detachable hinged lockable steel
door restricts unauthorised access
Application
The HSDI – 3 is a voice frequency,
high-security, bi-directional,
intertripping equipment which can
provide two separate protection
signalling commands over a single
telecommunications link.
Intertripping, also known as transfer
tripping, is the controlled tripping of a
circuit breaker so as to complete the
isolation of a circuit or piece of
apparatus. It is initiated from
protection at a remote location to
effect local tripping independent of
the state of the local protection. The
HSDI – 3 is used in a two-point scheme
to effect the tripping of remote circuit
breakers and to disconnect faulty
lines, transformers, generators,
2
Figure 1: HSDI – 3 with hinged front door open.
reactors, capacitors and other main
plant from remote current infeeds, and
to relieve abnormal system loading
conditions, see Figure 2: Principle of
intertripping.
A flexible design together with a
choice of modem signalling speeds
allows the equipment to be configured
to meet requirements for maximum
intertripping times ranging between
19.5ms and 61ms.
20 unique codes provide very high
inter-system security, so that many
systems can be installed in the same
substation with safety.
Economies in the provision of
VF circuits can be realised by the use
of the second trip facility as a contactto-contact repeat of another intertrip
command from a second location.
Equally when the 600 baud modem is
fitted, bandwidth is available for the
combination of other narrow band
protection signalling equipment such
as GEC ALSTHOM SD15, via the
auxiliary ports.
Description
The HSDI – 3 consists of plug in
modules housed together in a 6U
(266mm) high case suitable for
483mm rack mounting.
The modem is available as either 600
baud or 1200 baud option using
internationally recognised signalling
frequencies.
Trip inputs to the equipment are via
opto-isolated circuitry contained in an
interface module along with the
outputs in the form of high speed reed
relay elements.
When two trips are required, a
second interface module is supplied.
The functional block diagram for
HSDI – 3 is shown in Figure 3.
Opto-isolated inputs control the
transmitter where a digital bit pattern
or coded message is generated at a
baud rate determined by a clock
pulse from the modem.
Normally a channel monitoring
message is produced. When a trip
input occurs, the monitor message is
replaced by a message with a code
corresponding to Trip 1 or Trip 2 as
appropriate. Code format and
operation are shown in Figure 4.
Location A
Protection
relay
scheme
Location B
Voice frequency
communication
link
HSDI – 3
The message data is transferred
serially into the modem where it is
used to modulate a voice frequency
carrier signal using frequency shift
keying (FSK).
HSDI – 3
Circuit
breaker
The FSK signal is then transmitted over
a suitable voice frequency channel to
the equipment at the remote end.
Upon reception of the voice frequency
signals, the modem demodulates the
received FSK signals and transfers the
received data to the receiver module.
When a complete message has been
received, which exactly matches the
monitor, Trip 1 or Trip 2 code settings
of the receiver, the corresponding
output is provided.
Additional security is provided by a
bit width quality check on each bit of
the message and the requirement that
the monitor condition must have been
established for some time before a trip
output is permitted.
Voice frequency signals are always
being sent whether trip conditions are
present or not. This allows the
equipment at the receiver to
continually monitor the integrity of the
communications link and to generate
alarms in the event of the link not
functioning correctly.
Light emitting diodes (led) are
provided to indicate trips set, trips
received, test and alarm status. User
selectable settings for monitor and trip
codes together with a number of timer
settings such as the minimum output
contact closure time etc. are provided
by internal switches and links.
A hinged lockable steel door through
which the led indications are visible, is
provided to enable access to be
restricted to authorised personnel.
Test features are included as an aid to
commissioning work etc.
● Monitor points on front panels
● Analogue loop-back
● Test code generation
Figure 2: Principle of intertripping (unidirectional)
Transmitter
Receiver
Monitor
Monitor
Interface 1
Interface 1
Test
Trip1
input
Send
data
Clock
Trip2
input
Trip1
ouptut
Decode
Code
Interface 2
Intertripping faulty alarm
Receive
data
Interface 2
Trip2
ouptut
Modem
Send
Receive
V.F. alarm
From
aux.
4 wire line
To
aux.
Figure 3: HSDI – 3 functional block diagram
MESSAGE FORMAT (15 BIT)
tm
O O O I
tm = 25ms at 600 baud
(12.5ms at 1200 baud)
X X X X X X X X X X X
Variable
settings
Monitor 'I'
Trip '0'
(20 recommended monitor
and trip codes)
SYNC code
OPERATION
Inputs
Trip 1 1
0
Trip 2 1
0
Messages
M – Monitor code M
T1 – Trip 1 code
T2 – Trip 2 code
Trip 1 1
Inputs
0
Trip 2 1
0
M M M M M
T1 T1 T1 T1 T1
M M
tm
T1 T2 T1 T2 T2 T2 T2 T2 T2 T2
M M M
Count
T2
Figure 4: HSDI – 3 message format and operation
3
Trip1
+110V
+48V
Send
intertrip
command
Intertrip
initiation
Send and
receive
circuits
(48V system)
Common
Source
resistors –VE
"Test
send"
B6
2
1
B4
85–1
B9
B1
10
195
B20
10
195
4
"Timer" 3 85–2
B10
B11
85–3
B12
B13
B3
Test
85–4
B14
B15
85–5
B16
B17
85–6
Initiate
B8
B7
B2
Test
indication
supply (110V)
Test switch
B5
B18
B19
Intertrip
receive (1)
Intertrip
receive (2)
Intertrip
receive (3)
Intertrip
receive (4)
Intertrip
receive (5)
Intertrip
receive (6)
Supply
Reflex
Trip 1
(When supplied)
(When supplied)
When supplied, trip 2 as trip 1 above
(terminals A1 – A20)
Trip 2
Timing
test
facilities
Trip 2
C23
C5
Send and
receive
circuits
(48V system)
RLA–1
+VE
+
–
–
C4
Earth
C2
Equipment 0V
C9
Rated DC supply
48V or 24V
Rated alarm supply
48V or 24V
Clean earth
Protection earth
C26
C7
C8
C1
RLA–2
C24
C25
12V
C3
Earth
C21
C22
C6
Intertripping faulty
alarm (1)
Intertripping faulty
alarm (2)
C20
0V
C18
C19
V.F. Alarm
Earth stud
Modem
Receive
Send
Auxiliary
V.F.
equipment
Send
See note 1
Receive
C16
15
C17
8
C14
SK1
1
C15
9
7
C10
14
C11
PL1
2
10
Note 1:
VF connections may be made directly to the modem using
15 – way "D" type connectors SK1 & PL1. This arrangement is
preferred whenever interposing line isolating transformers
are not utilised. Caution – The method of line termination
and characteristics of any auxiliary equipment may be
subject to approval by the local telecommunication authority.
Figure 5: External connection diagram
4
C12
C13
V.F. Send
See note 1
V.F. Receive
4 wire
line
Technical Data
Trip times
1200 baud
600 baud
}
15 bit message
19.5ms max*
36ms max*
*Note:
These are maximum times for a single trip command. If two trips occur
simultaneously, one of the trip times may be extended to 32ms max (1200 baud)
and 61ms max (600 baud).
Auxiliary supply
Voltage
Nominal (V)
Operative range (V)
Equipment and Alarm
24
48
21 – 30
43 – 60
Burden
10W max
Supply interruptions
IEC 255–11
Supply ripple
IEC 255–11
The equipment is not affected by
interruptions in the auxiliary supply of
up to 10ms duration.
The equipment is not affected by an
ac component in the auxiliary supply
of up to 12% of the rated dc value.
Trip inputs
Send intertrip command voltage
(selected by tap)
ESI 48–4 class EB–I
Burden per input
Minimum trip input pulse
duration
Trip outputs
Trip and alarm output
contact ratings:
Nominal (V)
Operative range (V)
48
110/125
24-60
66-143
2.5W at 54V
7W at 110V
The trip input must be present for the
duration of the trip times given above.
4 form A per trip (optional 6)
(4 normally open)
Make and carry
continuously
50VA with maxima
of 3A and 250V dc
Make and carry
for 0.2s
1200VA with
maxima of 10A and
700V dc (L/R >10ms)
Break
DC 50W resistive
25W inductive
(L/R = 10ms)
5
Modem
BABT approved for 4-wire 600Ω balanced termination. User selectable 2-wire
and high impedance line options for circuits not subject to BABT approval.
Transmission rates
Transmission frequencies
600 baud options
1200 baud
600 baud
1200 baud
1500 ±200 Hz (CCITT V23)
2500 ±200 Hz
1700 ±400 Hz (CCITT V23)
Voltage withstand
Insulation IEC 255-5
2kV rms for 1 minute between all
circuits, apart from power supply
(500V).
1kV rms for 1 minute across normally
open contact pairs.
High voltage impulse†
IEC 255-5
5kV peak, 1.2/50µs, 0.5J between all
independent circuits.
5kV peak, 1.2/50µs, 0.5J across
terminals of the same group.
High frequency disturbance†
IEC 255-22–1 (class III)
2.5kV peak in common mode between
all circuits and case.
1.0kV in differential mode across all
circuits.
Fast transient disturbance†
IEC 255–22–4 (class IV)
4.0kV
Electrostatic discharge
IEC 255–22–2 (class III)
8kV
† Note:
These tests are not applicable to the voice frequency circuits which are intended
for high speed signalling and cannot therefore be protected against galvanically
coupled high frequency interference. Special care must be taken to avoid or
suppress all kinds of interference by careful installation planning and the use of
balanced and shielded interface cables and the use of high voltage isolating
transformers where appropriate.
Environmental withstand
Temperature
Storage and transit
IEC 68-2-1
–25˚C to +70˚C
Operating
IEC 68-2-2
–10˚C to +55˚C
Humidity
IEC 68-2-3
Long term damp heat
56 days at 93% RH and +40˚C
Vibration
IEC 255–21–1 (class I)
6
Mechanical durability
10,000 operations minimum
Weight
14.6 Kg
446
Terminal Terminal Terminal
Block ‘A’ Block ‘B’ Block ‘C’
483
331
Intertripping faulty
Before working on
this equipment
permission must be obtained
from Grid Control and the
appropriate "intertripping
channel test" switches must
be in the "test"position
HSDI–3
NOM
height
6U
Equipment
Rack detail
Transmitter
Receiver
483 (19') rack detail
to IEC 297
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
Rear View
(with cover removed)
Side view
Blank panel
U = 44,45
32
Modem
Front view
Blank panel
38
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
Input/output
266
(6U NOM) 190
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
Blank panel*
6
Power supply
465
Front view showing arrangement of modules
for single trip arrangement (cover removed)
*For two trips, blank panel replaced
by input/output module
Terminal blocks (Klippon type)
RSF–1
A1– A20, B1– B20
RSF– 2
C1– C9
SAK2–5
C10 – C17
SAK– R
C18 – C26
Figure 6: Case outlines
Cases
HSDI – 3 is provided in a 483mm rack
mounted case, (See Figure 6)
Information Required with
Order
Auxiliary supply voltage
Modem baud rate
Modem signalling frequency
(600 baud only) 1500Hz or 2500Hz
Monitor/trip code number
Number of trips
Number of intertrip receive contacts
per trip
Label information
7