Answer / nihar ranjan mandal

Amount of vacuum required to quench the arc at 132 KV level
will be very high. It is difficult to maintain that amount
of vacuum in practical purpose. Now a days we use GIS( gas
insulated substation for 132KV level. Where arc is quenched
in hydrogen chamber.

Answer / karunakar

Ionisation at higher voltages causes arcing between breaker
contacts hence deteoriation of contactors. This raises
another methods for arc quenching.. so for medium voltages
currents upto 3000A VCB's have longer life and better
operability.

Answer / deepak jha

Degree of Vacuum required for quenching of ARC at 132 kV
level system fault is very high and its very difficult to
maintain that much degree of Vacuum so don't use VCB in 132
kV level. we generally used SF6 for this purpose.

Answer / jobmonjacob

Vacuum restriction.

Answer / jobmon jacob

Factors contributing to interuptor selection are 1)voltage
2)metallurgy 3)vacuum 4)size 5)sc rating6)current chopping etc.

Answer / raghu

In 132kv and above switch gear required very high vacuum to quenching arc during making/breaking the contacts, now a days we r using gas insulated and sf6 switch gears for proper operation.

How to know the back up time for a 5KVA UPS which is connected to 15 nos. of computers? Is there any formula for this? pls. tell me.

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