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Periodic Testing work in Electrical Sub-stations

The relay should be tested

a.     Annually

b.     Whenever mal-operation is suspected

c.      While revising the relay settings

2.           Breaker opening and closing time

a.     At the time of commissioning

b.     Annually during service

c.      Whenever trip or closing coils are changed

d.     Whenever major repairs to opening mechanism are done

e.      Whenever breaker contacts are changed

3.           Station Earth resistance →   Annually

4.           Meggering (IR value) of Transformer, CT, PT & CB

a.     At the time of commissioning

b.     Annually during service

c.      If required after any fault.

5.           Other specific testing viz. tan ∂ measurement, Leakage Current Monitoring (LCM) of LA, CB dynamic resistance, DUE factor etc.

a.     At the time commissioning

b.     Once in two years.

At the time of overhauling/ major repairing

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