GE L90 Instruction Manual page 560

CONTROL ELEMENTS
The trip output element works in association with other L90 elements that must be programmed and in-service for
successful operation. The necessary elements are: recloser, breaker control, open pole detector, and phase selector. The
recloser must also be in the "Reset" state before a single pole trip can be issued. Outputs from this element are also directly
connected as initiate signals to the breaker failure elements.
At least one internal protection element or digital input representing detection of a fault must be available as an input to
this element. In pilot-aided scheme applications, a timer can be used to delay the output decision until data from a remote
terminal is received from communications facilities, to prevent a three pole operation where a single pole operation is
permitted.
The trip output element is used to aggregate inputs from appropriate protection elements (including 87L line differential,
distance, and instantaneous overcurrent functions) to provide single-pole tripping. The line current differential function is
hard-wired through the 87L TRIP function, which has to be enabled and configured properly.
The 87L TRIP function collects inputs from both the 87L line differential and 87L DTT functions. It can be supervised by the
disturbance detector and determines if the fault type is single-line-to-ground or multi-phase. The 87L TRIP function sends
a direct command to the trip output element to execute appropriate tripping action without any consultation with phase
selector.
Other protective functions, such as distance and overcurrent, need to be assigned to appropriate trip output single pole or
three pole inputs and require phase selector fault identification for tripping action. A timer defined by the
setting can be used to delay the output decision from other local protection elements to give 87L operational
PRIORITY
priority. This prevents three pole operation where a single pole operation is permitted.
To ensure correct operation of the single pole tripping feature, any non-distance protection used for single pole
tripping (such as high-set overcurrent using the instantaneous or directional overcurrent elements) must be
blocked by the
overcurrent phase A is blocked by
5
protection.
The following settings are available for the trip output element.
— This setting is used to select the required mode of operation. If selected to "3 Pole Only" outputs for all three
TRIP MODE
phases are always set simultaneously. If selected to "3 Pole & 1 Pole" outputs for all three phases are set simultaneously
unless the phase selector or a pilot aided scheme determines the fault is single-phase-to-ground. If the fault is identified as
being AG, BG, or CG only, the operands for the faulted phase are asserted.
TRIP 3-POLE INPUT1
that is not wanted to initiate a single pole operation (for example, phase undervoltage). Use a FlexLogic OR-gate if more
than six inputs are required.
TRIP 1-POLE INPUT1
that is wanted to initiate a single pole trip-and-reclose if the fault is single phase to ground (for example, distance zone 1).
Use a FlexLogic OR-gate if more than six inputs are required. The inputs do not have to be phase-specific as the phase
selector determines the fault type.
The
AR FORCE 3-P TRIP
calls for a three-pole trip if any protection element configured under
detector provides blocking inputs to distance elements, and therefore the latter resets immediately after the
operand asserts. For other protection elements used in single-pole tripping, ensure that they reset immediately after
tripping, otherwise the fact that they are still picked up is detected as an evolving fault and the relay trips three-poles. For
example, if high-set phase instantaneous overcurrent is used (
is used for blocking phase A of the instantaneous overcurrent element. In this way, after tripping phase A, the phase a
instantaneous overcurrent element is forced to reset. Phases B and C are still operational and can detect an evolving fault
as soon as 8 ms after tripping phase A. Neutral and negative-sequence instantaneous overcurrent elements are blocked
from the
OPEN POLE BLK N
TRIP RECLOSE INPUT1
wanted to initiate three pole reclosing (for example, phase distance zone 1). Use a FlexLogic OR-gate if more than six
inputs are required. These inputs also include the
5-336
ΦA,
OPEN POLE OP OPEN POLE OP
OPEN POLE OP ΦA
to — These settings are used to select an operand representing a fault condition
TRIP 3-POLE INPUT6
to — These settings are used to select an operand representing a fault condition
TRIP 1-POLE INPUT6
operand is asserted by the autorecloser 1.5 cycles after single-pole reclosing is initiated. This operand
operand unless the pickup setting is high enough to prevent pickup during single-pole reclosing.
to — These settings select an operand representing a fault condition that is
TRIP RECLOSE INPUT6
ΦB, or OPEN POLE OP ΦC operands. For example, instantaneous
operand. This blocking condition is pre-wired for distance
TRIP 1-POLE INPUT
TRIP 1-POLE INPUT X
to
TRIP 1-POLE INPUT1 TRIP 1-POLE INPUT6
L90 LINE CURRENT DIFFERENTIAL SYSTEM – INSTRUCTION MANUAL
CHAPTER 5: SETTINGS
TRIP PILOT
remains picked-up. The open pole
TRIP 1-POLE
: "PHASE IOC1 OP"), then OPEN POLE OP ΦA
values, which are intended to