Protection Engineering Basics and Schemes Protection Engineering | Page 81

here you can see our 13.8 Kv circuit breaker is coupled
with two breakers and one reactor, reactor is current
limiting device and harmonic suppressor. neutral
balance CT is low rated CT with 10/5A rating, the current
in neutral while capacitor bank is healthy will be ZERO,
but during unbalancing some current flow in this CT and
relay associated with this CT signaled breaker to get trip.
in this case class of CT is 5p with ALF of 20 , means this CT
will have errors less than 5% up to 200A in primary
neutral circuit which will be accidental but not usual.
pg. 81