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.

For 132 KV line, PT or CVT which is prefered for measuring & protection? is there any IS or IEE standard available?

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