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

D90
Chapter 15: Theory of operation

Distance elements

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

Theory of operation

This chapter outlines advanced information on operation.
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 548: D90 distance algorithm
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