Answer / md ahmeduddin farooqi

the maintenance cost, I believe that SF6 Breaker is still
cheaper than the Vacuum Circuit Breaker because Vacuum
Circuit Breaker does have any limited operation life. For
Vacuum Circuit Breaker, there is limited operation life. You
need to change all the Vacuum breaker poles if the operation
life is up.

I don't know what is your intake voltage in this case, for
us, we use SF6 Circuit breakers for all the 11KV, 33kv.
Current interruption in a high-voltage circuit-breaker is
obtained by separating two contacts in a medium, such as
SF6, having excellent dielectric and arc quenching
properties. After contact separation, current is carried
through an arc and is interrupted when this arc is cooled by
a gas blast of sufficient intensity.

Gas blast applied on the arc must be able to cool it rapidly
so that gas temperature between the contacts is reduced from
20,000 K to less than 2000 K in a few hundred microseconds,
so that it is able to withstand the transient recovery
voltage that is applied across the contacts after current
interruption. Sulphur hexafluoride is generally used in
present high-voltage circuit-breakers (of rated voltage
higher than 52 kV).

Answer / veeresh m y

SF6 Used in HT Side is Only the Main Reason is TO Avoide
the Heavy Sparks In the High Voltage Side.

Answer / rajmohan

quick arc quenching

Answer / ashoke

Because the air circuit beakers are unable to quench the arc
immediately due to High voltage and current.So a more
efficient arc quenching medium is require like
oil,vacuum,SF6 in side.The HT contains higher voltage level
and the fault current is also higher so a brief description
is needed for choosing the appropriate CB.

Answer / arvind kumar sinha

we use VCB and sf6 due to its high dielectric strenghth.

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