GE D60 Instruction Manual page 720

SINGLE-POLE TRIPPING
• Determine whether a single or three-pole operation is to be performed
• Initiate tripping of breaker poles A, B, and C, either individually or as a group
• Initiate breaker failure protection for phases A, B, and C, either individually or as a group
• Notify the open pole detector when a single pole operation is imminent
• Initiate either single or three-pole reclosing
• Notify the phase selector when a trip operation is imminent
When notified that a single pole operation has been initiated, the open-pole detector
• Initiates blocking of protection elements that can potentially maloperate when a breaker pole is open
• Instructs 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 is described as follows. 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
elements,
GND DIR O/C FWD
pole trip when appropriate (
scheme issues a single-pole trip. It is assumed that when tripping three poles, both the zone 1 and the POTT initiate three-
pole reclosing. This is achieved by setting
TRIP RECLOSE INPUT-3
It is assumed for this discussion that the relay features that are shown in the Single-Pole Operation figure have 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
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.
9.5.1.2 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
distance zone 1 (AG element) responds to the 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
9
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.
9-24
: "NEG SEQ OC1
GND DIR O/C REV
FWD,"
: "GND DIST Z1
TRIP 1-POLE INPUT-1
TRIP RECLOSE INPUT-1
: "PHS DIST Z1
OP."
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
: "NEG SEQ OC1 REV"). Zone 1 is configured to issue a single-
TRIP 1-POLE INPUT-2
OP,"
: "POTT TRIP
TRIP RECLOSE INPUT-2
3P,"
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
D60 LINE DISTANCE PROTECTION SYSTEM – INSTRUCTION MANUAL
CHAPTER 9: THEORY OF OPERATION
: "PHS DIST Z1 OP"). By default, the POTT
: "GND DIST Z1 OP," and
operand. Ground
PHASE SELECT AG
TRIP PHASE A
(even before it is
OPEN POLE OP FA
(OPEN POLE BLK
AB, OPEN POLE BLK CA
blocks the ground distance AG