Alstom SHPM 101, Service Manual

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SERVICE MANUAL R5888C
QUADRAMHO Chapter 2
Page 58 of 74
Operation of the voltage transformer supervision contact (97X–1) and the power
swing alarm contact (95–1) are described under the appropriate descriptions of
these features.
5.16.31 Trip A, Trip B and Trip C contacts
94A–1 94A–2 94B–1 94B–2 94C–1 94C–2
These contacts are used to initiate single pole tripping of the breaker for single
phase-to-ground faults in Zone 1 or carrier aided Zone 2. Single pole trips can
only be obtained with even numbered scheme options (code selection numbers
X and Y). For all other types of fault, and with odd numbered scheme options, all
these contacts close simultaneously with the three phase tripping contacts 94T–1
and 94T–2. This also occurs if the channel-in-service opto isolator is not energised
and a signal aided scheme has been selected. The trip contacts are latched in for
a minimum of 60ms, and if a 3 phase trip has been issued, it will be maintained
until all trip signals to the trip output logic have been removed. The trip output logic
is implemented as software in the scheme logic microcomputer (see Figure 72).
The single pole tripping contacts can also be used for initiating auto-reclose and
starting the breaker fail protection. In some cases it may be necessary to provide
external repeat relays if multiple, clean contacts are needed.
5.16.32 Trip three phase contacts 94T–1 and 94T–2
These contacts are used for initiating three pole tripping of the circuit breaker,
initiating three pole auto-reclose and starting the breaker fail protection. If it is
intended only to use odd numbered scheme options, then six other repeat contacts
are available.
5.16.33 Any trip contacts 94–1 and 94–2
These contacts close for any trip signal (single or three pole) produced by the relay
and as such, are particularly useful for checking the relay reach, operating time,
etc, during commissioning and routine testing. In order to realise its usefulness
more fully, the contact 9401 has been routed through the heavy current plug
contacts 1Z7–1Z8, in order that it may be accessed from the front of the relay
whilst secondary injecting during commissioning tests, etc. (See Figure 67).
5.16.34 Block auto reclose contacts 96–1
The following conditions will cause the block auto-reclose contact (96–1) to be
closed by the scheme logic:
a) Any Zone 2 time delayed trip.
b) Any Zone 3 time delayed trip.
c) Any switch on to fault trip.
d) Signalling channel not in service (CIS opto isolator not energised) if switch SW6
is set to right hand position and scheme selected is a signal aided scheme.
e) A 3 phase (Zone 1/signal aided trip) fault occurs and switch SW4 is in the
right hand position.
The block auto-reclose logic, Figure 73, is implemented as software in the scheme
logic microcomputer.
The contact is kept closed for a further 100ms after all block auto-reclose
conditions have been removed. This represents a delay in drop off for contact
96–1.