GE C60 Instruction Manual page 526

SINGLE-POLE TRIPPING
Because the line is de-energized, the line pickup element is armed. The recloser is presently enabled. An operator requests
that breaker control close the breaker, and it operates output relays to close breaker poles A, B, and C. This operator
manual-close request is also forwarded from breaker control to recloser, which becomes disabled, de-asserting its
"Enabled" output. This output is transferred to trip output, where it converts any input request for a single pole operation
into a three-pole operation. At the recloser, the
The breaker closes and status monitoring contacts on the breaker poles change state; the new breaker pole states are
reported to breaker control, which in turn transfers these states to the recloser, trip output, breaker failure, and open pole
detector. Because a fault is not detected the
asserts the "Enabled" output, informing the trip output element that single-pole trip operations are now permitted. When
normal voltage appears on the line, the line pickup element is disarmed. As the local line breaker has not tripped, the
operator closes the breaker at the remote end of the line, placing the line in service.
Several scenarios are considered as follows.
8.2.1.2 SLG fault
At this moment, the request to trip is placed for the trip output. As the fault is recognized as an AG fault, the
operand is asserted by the trip output. This signal is passed to the breaker control scheme and results in tripping pole A of
the breaker.
Simultaneously with the
detector responds to the
actually opened). The
contact. At this moment the open pole detector responds to the breaker position and continues to indicate phase A
opened. This indication results in establishing blocking signals for distance elements
operands are asserted). If neutral and negative-sequence overcurrent elements are mapped into the trip output to trigger
single-pole tripping, they must be blocked with the
operand must be assigned through the block setting of the overcurrent element. The two latter operands
OPEN POLE BLK N
block phase distance AB and CA elements, respectively (all zones); the
elements (all zones). As a result, the
distance elements remain operational guarding the line against evolving faults: BG, CG, and BC.
The operand initiates automatically a single-pole autoreclose. The autoreclose is started and asserts the
TRIP 1-POLE
operand. This operand keeps blocking the phase selector so that it does not respond to any subsequent events. At the
same time, the operand removes zero-sequence directional supervision from ground distance zones 2 and 3 so that they
can respond to a single-line-to-ground fault during open pole conditions.
The
AR FORCE 3-P TRIP
any existing trip request. In this case, none of the protection elements is picked up at this time, therefore no more trips are
initiated.
When the recloser dead time interval is complete, it signals the breaker control element to close the breaker. The breaker
control element operates output relays to close the breaker.
When pole A of the breaker closes, this new status is reported to the breaker control element, which transfers this data to
the breaker failure, autorecloser, open pole detector and trip output elements. The response at breaker failure depends on
the programming of that element. The response at the autorecloser is not relevant to this discussion. At the open pole
8
detector, the blocking signals to protection elements are de-asserted.
If the fault was transient, then the reset time expires at the autorecloser and the
asserted, returning all features to the state described at the beginning of this description.
If the fault was permanent, appropriate protection elements detect this and place a trip request for the trip output
element. As the
AR FORCE 3-P TRIP
The response of the system from this point is as described earlier for the second trip, except that the autorecloser locks out
upon the next initiation (depending on the number of shots programmed).
8-6
AR1 BLK TIME @ MAN CLOSE
AR1 BLK TIME @ MAN CLOSE
operand, the
TRIP PHASE A
signal by declaring phase A open by asserting
TRIP PHASE A
signal resets only after the breaker actually operates as indicated by its auxiliary
TRIP PHASE A
and
Z1 OP Z2 PKP
operand is asserted 1.25 cycles following autoreclose initiation. This operand acts as an enabler for
is still asserted, the request is executed as a three-pole trip.
timer is started.
times out and the recloser is enabled, which
operand is asserted to activate the open pole detector. This
TRIP 1-POLE
operand, specifically provided for this purpose. The
OPEN POLE BLK N
OPEN POLE FA OP
operands that were picked-up reset immediately. The following
C60 BREAKER PROTECTION SYSTEM – INSTRUCTION MANUAL
CHAPTER 8: THEORY OF OPERATION
TRIP PHASE A
(even before it is
OPEN POLE OP FA
(OPEN POLE BLK
AB, OPEN POLE BLK CA
blocks the ground distance AG
and outputs are de-
AR FORCE 3-P TRIP RIP
AR RIP