Protection Engineering Basics and Schemes Protection Engineering | Page 67

As you see the above switch is Time delay break / Drop
off switch.
2.3 Trip circuits:
Trip circuits are used for isolation of protected
equipment. They are basically of three types
 Series Sealing
 Shunt Reinforcement
 Shunt reinforcement series sealing
2.3.1 Series Sealing:
In it, across Protection Relay (PR) contact we connected
one auxiliary contact for holding circuit, when protection
relay operate/pick up, make contacts of PR energized
and small amount of current also flow in parallel
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