Theory Of Operation; Plus Distance Elements; Distance Element Arming Logic - GE D90 Plus Instruction Manual

D90
Chapter 15: Theory of operation
The D90

Distance element arming logic

PLUS
D90 LINE DISTANCE PROTECTION SYSTEM – INSTRUCTION MANUAL
Plus
Line Distance Protection System

Theory of operation

This section describes the basic theoretical principles behind the operation of D90
Plus
distance elements
The distance element is composed of two separate algorithms. The first is a conventional
frequency domain (phasor) algorithm based on the UR-series D60 implementation. The
second is a time domain algorithm that achieves sub-cycle operating times. The two
algorithms run in parallel and each can independently issue a trip command.
The distance element arming logic grants permission to the time domain algorithm only if
all of the following conditions are met for five cycles prior to a disturbance.
• Zero-sequence current is less than 0.2 pu.
• Negative-sequence current is less than 0.2 pu.
• Zero-sequence voltage is less than 0.2 pu.
• Negative-sequence voltage is less than 0.2 pu.
Plus
Figure 462: D90 distance algorithm
Plus
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