Protection Engineering Basics and Schemes Protection Engineering | Page 72

Purpose of resistor is same in both circuits is same as
mention in H4.
2.4.3 H7 Circuit Scheme:
Nowadays trend is Scada. In this scheme we employees
the scada in protection scheme.
Here we simply we employee one extra circuit in parallel
with under protected relay and breakers, in which 2 time
delay contacts are in place, And one more time delay
contact is used for Scada alarm.
Operation : if circuit remain healthy , both coil A and B
remain energize and associated make contacts remain
open, when circuit got faulty associated make contacts
energizes and Coil C energizes and associated break
contact open and alarm situation occurs. We employees
delay switches in this circuit to avoid mal-operation at
short duration interruption.
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