AC Close, DC Trip

[cvirgil]

Can anyone give a quick summary on how the operation of AC Close and DC trip work on MV breakers. I've also heard that there is DC close and DC trip.

What are the benefits of either design?

Thanks.

 

[wfowfo]

The disadvantage of the AC close is that if you lose station service, you can't reclose your device.

 

[ScottyUK]

DC control usually requires a tripping battery. It requires maintenance and periodic replacement. If maintained well it should prove very reliable so you will (almost!) always be able operate your switchgear.


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One day my ship will come in.
But with my luck, I'll be at the airport!

 

[bacon4life]

Our HV breakers have an AC motor to charge the closing springs with a DC motor as a backup with trip & close coils energized by DC. Perhaps this allows a smaller battery/charger or saves cycling the batteries.

AC close/DC Trip could also refer to a breaker that uses a capacitor to store enough energy to trip. Useful in remote locations without batteries like poletop reclosers.