GE D90 Plus Instruction Manual page 663

Line distance protection system

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CHAPTER 15: THEORY OF OPERATION

LINE DISTANCE PROTECTION SYSTEM – INSTRUCTION MANUAL

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 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

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

performs the following functions:

Initiates blocking of protection elements that potentially can misoperate when a

breaker pole is open

Instructs 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 is described. The line 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 561: Single-pole operation

SINGLE-POLE TRIPPING