Answer Posted / ram kumar singh
It is used in HT installations.Arc quenching medium is
vaccum.VCB has one fixed contact and another moving
contact.Vaccum aprox.above one mili bar required.IR value
of Vacuum CB will be very good when open condition.Surge
suppressor is required in series .Contact make & break in
Vaccum.Dieclectric strength becomes very good in VCB.It has
more details.
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