Answer / s naidu

in a vcb this are main relay
1-phase unbalance relay -2nos
2-earth leakege trip relay
3-TR common fault relay

in acb this are main relay
1-load balancing relay
2-u/o voltage relay
3-earth fault relay
4-master trip realy

this tests are carried out generally on both CB
i-cb in open & close position test
2-continuity of contacts
3-manual closing,electrical closing, remote closing
4-remote tripping though protection relays
5-check spring charging motors are in working

relays calibrated operating characteristics to electrical
circuits.

Answer / vijaykumar

Protection of the feeders depends upon the load but not on
the type of breaker used.
VCB-measure the Contact resistance and breaking
resistance,tripping time other mechanical interlockings for
the breaker Mechanisms.
ACB-Check the contact reisitance and the contact tips which
are visible to naked eyes,arching chutes,since air is the
quenching media.

where AVR is connected in power plant.

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