SINGLE-POLE TRIPPING
564
The trip output element receives requests for single-pole and three-pole trips and three-
pole reclose initiation. It then processes these requests to generate outputs that are used
to perform the following functions.
•
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-pole 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 will
perform the following functions.
•
Initiate blocking of protection elements that could potentially misoperation when a
breaker pole is open.
•
Instruct the phase selector to de-assert all outputs, as an open pole invalidates
calculations.
Single-pole operation on a line in a single breaker arrangement will be described. The line
Plus
is protected by a D90
using the line pickup and zone 1 phase and ground distance
elements. It also implements a permissive overreaching transfer trip scheme using zone 2
phase and ground distance elements, as well as negative-sequence directional
overcurrent elements. Zone 1 is configured to issue a single-pole trip when appropriate:
Figure 475: Single-pole operation
PLUS
D90
LINE DISTANCE PROTECTION SYSTEM – INSTRUCTION MANUAL
CHAPTER 15: THEORY OF OPERATION