Protection Engineering Basics and Schemes Protection Engineering | Page 63

Chapter 2
Auxiliary Relays and Trip circuits
2.1 Auxiliary Relays
Auxiliary means associated help, auxiliary relays in
association with Protection Relays used for signaling,
alarms, contact addition, tripping assistance and data
transference to main relay through long distance
By operation auxiliary relays divided in 4 types
 Alarm
 Tripping contacts (Repeat contactor)
 In lines where distance between relays and
associated protected element is more
 Contact addition
These relays are called as all or nothing relays.
Usually these relays are represented by K, M or user
defined letters in any circuit
drawing.
You can observe one simple
auxiliary relay at the on off
switch of circuit breaker(this
is repeat contactor type and
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