Transfer Trip - GE SPA11A Instructions Manual

PILOT WIRE CONDITION
UNIT
uc
oc
GND
t
Detection time of each function is the time to close its contact upon the
occurrence of the condition listed in the table.
tt Restore time for each function is the time to reopen its contact when the
condition listed in the table is removed and normal circuit conditions are
restored.

TRANSFER TRIP

The SPA 11 B and SPA 12B relays can send a transfer-trip signal over the pilot wire to
initiate tripping at the other terminal(s). The signal can be sent from either the sending­
end relay (SPA 11 B) or the receiving-end relay (SPA 12B). It will initiate the tripping of both
the local and remote breakers on a two-terminal line, or of all three breakers on a three­
terminal line.
The transfer-trip signal is produced by energizing the coil of the TIA unit through an
external contact. When the TIA picks up, it reverses the polarity of the DC voltage applied
to the pilot wire through studs 7 and 8. The reversed-polarity voltage on the pilot wire
causes the operation of the transfer-trip (TI) unit in the local and remote SPA relays. The
n
output contact connected between studs 1 and 11 is provided with a target seal-in unit
and is recommended for tripping duty. The
auxiliary contact and has no target seal-in unit.
The operating time between energizing TIA at one end of the pilot wire and picking
n
up at the other end (remote) varies slightly with the length of the pilot wire, as
indicated below. The time to pick up the local unit is approximately two (2) cycles,
independent of the length of the pilot wire.
Short Pilot Wire
=
(Series R
Long Pilot Wire
=
(Series R
APPROXIMATE OPERATING TIMES
Open Circuit
Short Circuit
Grounded Conductor
0 ohm)
2000 ohms)
GEK-65512
TABLE V
DETECTION TIMEt
300 msec.
300 msec.
300 to 500 msec.
n
contact between studs 2 and 3 is an
Remote TI Pickup Time
approximately 4 cycles
approximately 5 cycles
8
RESTORE TIME tt
2000 msec.
700 to 2000 msec.
400 to 800 msec.
Remote TI Dropout Time
approximately 6 cycles
approximately 6 cycles