VCB or Fused Vacuum contactor
VCB or Fused Vacuum contactor
(OP)
What are the advantages/disadvantages of using a vacuum circuit breaker as opposed to a fused vacuum contactor for MV motor control. Obviously a fuse is not reuseable. Any other pitfalls in either decision?






RE: VCB or Fused Vacuum contactor
In case of critical motor applications and safety related drives such as fire water pump, you may not like the contactor to drop-off just because there is fault elsewhere in the system causing temporary under voltage.
May be, if you go for latched type contactors that is a different issue.
Otehrwise, the MV contactors save money in cable system design as the cable short circuit withstand could be lower with fuse back up available.
RE: VCB or Fused Vacuum contactor
In additional to Raghun post:
MV vacuum contactor is cheaper then MV vacuum CB.
Regards.
Slava
RE: VCB or Fused Vacuum contactor
The contact material of a vacuum contactor designed for motor switching will be different from the contact material of a vacuum circuit breaker designed for fault current interruption. The contactor will be less likely to generate over voltage transients when switching.
Barring any special circumstances the only valid reason I can think of to use a vacuum circuit breaker rather than vacuum contactor for medium voltage motor control would be in applications were motor currents and or voltages are higher than commonly available motor contactors. Examples could be large 13.2kV motors.
RE: VCB or Fused Vacuum contactor
Gianoli, motors concern are 10kV. Our client in china states that if we allow VCBs then this will give them more options for switchgear supplies. Problem lies with the withstand voltage as I understand. Chinese code requirements for withstand voltage are based on russian standards. We originally were asking for 28kV (75kV) impulse with the contactors with it being a 10kV system. As I understand Chinese code my be more stringent?
RE: VCB or Fused Vacuum contactor
RE: VCB or Fused Vacuum contactor
All MV motors should have surge protection at the motor in any event.