Single-Pole Tripping; Overview - GE L90 Instruction Manual

9.3 SINGLE-POLE TRIPPING

9.3SINGLE-POLE TRIPPING
a) INTRODUCTION
Single pole operations make use of many features of the relay. At the minimum, the trip output, recloser, breaker control,
open pole detector, and phase selector must be fully programmed and in service; and either protection elements or digital
inputs representing fault detection must be available for successful operation. When single pole trip-and-reclose is required
overall control within the relay is performed by the trip output element. This element includes interfaces with pilot aided
schemes, the line pickup, breaker control, and breaker failure elements.
Single pole operations are based on use of the phase selector to identify the type of the fault, to eliminate incorrect fault
identification that can be made by distance elements in some circumstances and to provide trip initiation from elements that
are not capable of any fault type identification, such as high-set negative-sequence directional overcurrent element. The
scheme is also designed to make use of the advantages provided by communications channels with multiple-bit capacities
for fault identification.
Volts
and
amps
Protection
elements
Inputs
Pilot-
aided
schemes
Setting Setting
Inputs Outputs
Communications
channels
AG
BG
CG
Setting
Line pickup
Multi-phase
Void
Setting
AR FORCE 3-P
The trip output element receives requests for single and three pole trips and three pole reclose initiation, which it then pro-
9
cesses to generate outputs that are used to:
• Determine whether a single or three pole operation should 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.
9-20
Phase selector
Block specific protection elements
Trip output
Setting
Single-pole
trip request
Setting
Single-pole
operation
SLG
faulted
phase
Permission
Reset
Three-pole
trip
request
Force Three-pole
three-oole operation
operation
Reclose request
Figure 9–9: SINGLE-POLE OPERATION
L90 Line Current Differential System
Reset
output
Single-pole
trip
Trip
A or B or C
Initiate breaker
failure
Three-pole
trip
Initiate
Trip
Initiate
AR Initiate 3-Pole
9 THEORY OF OPERATION

9.3.1 OVERVIEW

Fault locator
Volts
and
amps
Open
pole
detector
Breaker Breaker
1 and 2 1 and 2
pole state out-of-service
Inputs
Breaker
control
Outputs
Setting
Operator
Setting
Recloser
Multi-phase
837026A5.CDR
GE Multilin