GE D60 Instruction Manual page 512

9.5 SINGLE-POLE TRIPPING
• Notify the phase selector when a trip operation is imminent.
When notified that a single pole operation has been initiated open pole detector will:
• Initiate blocking of protection elements that could potentially maloperate when a breaker pole is open.
• Instruct the phase selector to de-assert all outputs, as an open pole invalidates calculations.
The operation of the scheme on a line in a single breaker arrangement will be described. The line is protected by a D60
relay using the line pickup and zone 1 phase and ground distance elements, and a permissive overreaching transfer trip
scheme (using zone 2 phase and ground distance elements as well as negative-sequence directional overcurrent ele-
ments,
GND DIR O/C FWD:
gle-pole trip when appropriate (
the POTT scheme will issue a single-pole trip. It is assumed that when tripping three-poles both the zone 1 and the POTT
shall initiate three-pole reclosing. This is achieved by setting
" ", and
GND DIST Z1 OP
It is assumed for this discussion that the relay features that are shown on Single pole operation diagram above have all
been programmed for the application and are in service. The description begins with line breakers open at both the local
and remote ends, and the operation of the scheme is described in chronological order.
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 man-
ual 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 nor-
mal 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 below.
b) SLG FAULT
An AG fault occurs close to the considered relay. Immediately after the fault, the disturbance detector (50DD) picks-up and
activates the phase selector. The phase selector recognizes an AG fault by asserting its
Ground distance zone 1 (AG element) responds to the fault. As the fault is close to the relay, phase distance zone 1 (AB,
CA elements) may respond to this fault as well. In any case, a single-pole operation is requested by zone 1 via the
and/or
DIST Z1 OP PHS DIST Z1 OP
At this moment the request to trip is placed for the trip output. As the fault is recognized as an AG fault, the TRIP PHASE A
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. The latter detector responds to the
(even before it is actually opened). The
ΦA
by its auxiliary 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 out-
POLE BLK CA
put to trigger single-pole tripping, they must be blocked with the
purpose. The
OPEN POLE BLK N
9
latter operands block phase distance AB and CA elements, respectively (all zones); the
ground distance AG elements (all zones). As a result, the Z1 OP and Z2 PKP operands that were picked-up reset immedi-
ately. The following distance elements remain operational guarding the line against evolving faults: BG, CG and BC.
As zone 2 and/or negative-sequence directional elements pick up due to the fault, the permission to trip is keyed to the
remote end. Assume here that a single-bit channel is used. If so, no extra information is sent to the remote end, just permis-
sion to trip sent over the TX1 operand. Upon receiving permission to trip over RX1, the POTT scheme decides to trip. The
scheme will check the phase selector for phase type identification and will issue a trip for phase A by asserting the
operand. This operand is passed to the trip output and results in exactly same action as described above for zone 1.
TRIP A
9-22
" ",
NEG SEQ OC1 FWD
GND DIR O/C REV:
TRIP 1-POLE INPUT-1:
"
PHS DIST Z1 OP
TRIP RECLOSE INPUT-3:
AR1 BLK TIME @ MAN CLOSE
AR1 BLK TIME @ MAN CLOSE
operands.
operand, the
TRIP PHASE A TRIP 1-POLE
TRIP PHASE A
TRIP PHASE A
operand must be assigned through the block setting of the overcurrent element. The two
D60 Line Distance Protection System
"
NEG SEQ OC1 REV
" ",
GND DIST Z1 OP
TRIP 1-POLE INPUT-2:
TRIP RECLOSE INPUT-1:
".
timer is started.
times out and the recloser is enabled, which
operand is asserted. This operand activates the open pole
signal by declaring phase A open by asserting
signal resets only after the breaker actually operates as indicated
OPEN POLE BLK N
9 THEORY OF OPERATION
"). Zone 1 is configured to issue a sin-
" "). By default
PHS DIST Z1 OP
" ",
POTT TRIP 3P
TRIP RECLOSE INPUT-2:
PHASE SELECT AG
OPEN POLE OP
OPEN POLE BLK AB
operand, specifically provided for this
blocks the
OPEN POLE ΦA OP
GE Multilin
operand.
GND
,
OPEN
POTT