8-34
L60 Line Phase Comparison System
GE Multilin
8.2 SINGLE-POLE TRIPPING
8 THEORY OF OPERATION
8
•
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 in a single breaker arrangement will be described. The line is protected by a L60 using the
87PC, line pickup, and zone 1 phase and ground distance elements. 87PC and/or zone 1 is configured to issue a single-
pole trip when appropriate (
TRIP 1-POLE INPUT-1:
“
GND DIST Z1 OP
”,
TRIP 1-POLE INPUT-2:
“
PHS DIST Z1 OP
”). It is assumed
that when tripping three-poles both Zone 1 and 87PC shall initiate three-pole reclosing. This is achieved by setting
TRIP
RECLOSE INPUT-1:
“
87PC OP
”,
TRIP RECLOSE INPUT-2:
“
GND DIST Z1 OP
”, and
TRIP RECLOSE INPUT-3:
“
PHS 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
AR1 BLK TIME @ MAN CLOSE
timer is started.
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
AR1 BLK TIME @ MAN CLOSE
times out and the recloser is enabled, which
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.
The 87PC element must be applied according to the
Single-pole tripping applications
section in Chapter 9.
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
PHASE SELECT AG
operand. The
line phase comparison element (ANSI 87PC) and/or 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 line phase comparison element (ANSI 87PC) and/or the
GND DIST Z1 OP
and/
or
PHS DIST Z1 OP
operands.
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
TRIP PHASE A
operand, the
TRIP 1-POLE
operand is asserted. This operand activates the open pole
detector. The latter detector responds to the
TRIP PHASE A
signal by declaring phase A open by asserting
OPEN POLE OP
A
(even before it is actually opened). The
TRIP PHASE A
signal resets only after the breaker actually operates as indicated
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 (
OPEN POLE BLK AB
,
OPEN
POLE BLK CA
operands are asserted). If neutral and negative-sequence overcurrent elements are mapped into the trip out-
put to trigger single-pole tripping, they must be blocked with the
OPEN POLE BLK N
operand, specifically provided for this
purpose. The
OPEN POLE BLK N
operand must be assigned through the block setting of the overcurrent element. The two
latter operands block phase distance AB and CA elements, respectively (all zones); the
OPEN POLE
A OP
blocks 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.
Depending on response times, the actual trip is initiated either by zone 1 or by the line phase comparison element (87PC).
At the moment
TRIP 1-POLE
operand is asserted, the phase selector resets and no other trip action could take place. After
the trip command is issued all the picked up elements are forced to reset by the open pole detector.
NOTE
Summary of Contents for L60
Page 10: ...x L60 Line Phase Comparison System GE Multilin TABLE OF CONTENTS ...
Page 57: ...GE Multilin L60 Line Phase Comparison System 2 27 2 PRODUCT DESCRIPTION 2 3 SPECIFICATIONS 2 ...
Page 58: ...2 28 L60 Line Phase Comparison System GE Multilin 2 3 SPECIFICATIONS 2 PRODUCT DESCRIPTION 2 ...
Page 482: ...6 26 L60 Line Phase Comparison System GE Multilin 6 5 PRODUCT INFORMATION 6 ACTUAL VALUES 6 ...
Page 554: ...10 8 L60 Line Phase Comparison System GE Multilin 10 2 BATTERIES 10 MAINTENANCE 10 ...
Page 674: ...B 110 L60 Line Phase Comparison System GE Multilin B 4 MEMORY MAPPING APPENDIX B B ...
Page 704: ...C 30 L60 Line Phase Comparison System GE Multilin C 7 LOGICAL NODES APPENDIX C C ...
Page 720: ...E 10 L60 Line Phase Comparison System GE Multilin E 1 PROTOCOL APPENDIX E E ...
Page 732: ...F 12 L60 Line Phase Comparison System GE Multilin F 2 DNP POINT LISTS APPENDIX F F ...
Page 742: ...H 8 L60 Line Phase Comparison System GE Multilin H 3 WARRANTY APPENDIX H H ...