DC or AC Spring Charging Motor
DC or AC Spring Charging Motor
(OP)
Hi Friends,
Can anyone tell me what are the pros and cons of DC and AC spring charging motors for an 11kV circuit breaker?
Can anyone tell me what are the pros and cons of DC and AC spring charging motors for an 11kV circuit breaker?






RE: DC or AC Spring Charging Motor
old field guy
RE: DC or AC Spring Charging Motor
David Castor
www.cvoes.com
RE: DC or AC Spring Charging Motor
RE: DC or AC Spring Charging Motor
With an AC charging motor, you can't charge the breaker when station power is not available. However, if station power is not available, it's either during construction, a failure in the substation, or because of a larger outage.
A DC charging motor seems more convient, but most people don't take the time to understand the additional cost. The additional cost is in the form of possible larger battery needed, possible larger battery charger, effects of added noise on the DC bus.
A AC system may require you to evaluate the AC power for the substation, and maybe add additional backup sources for certion outage contengecies.
Either way some thinking should be involved.
RE: DC or AC Spring Charging Motor
Murphys Law applies: Everything goes wrong at once or cascades during an AC blackout. Not being able to reclose breakers as the springs are not tensioned can be disasterous. Especially in remote controlled unmanned stations where no one is available on site to recharge the springs by hand.
Exception: When only a weak 24 or 48 volt battery is available, it might be a concern.
rasevskii
RE: DC or AC Spring Charging Motor
DC is probably best, but you have to consider all situations and impacts as others have stated.
RE: DC or AC Spring Charging Motor
sonic02
RE: DC or AC Spring Charging Motor
RE: DC or AC Spring Charging Motor
RE: DC or AC Spring Charging Motor
RE: DC or AC Spring Charging Motor
RE: DC or AC Spring Charging Motor
With regards to diversity it needs to be considered if all the breakers could operate at the same time such as for a buszone fault.
I have seen AC spring charge motors used with a mechanical cranking handle as backup should there be a loss of AC supply.
Regards.
RE: DC or AC Spring Charging Motor
You do not mention the battery voltage available, or whether this is a manned or unmanned installation. The DC choice is obviously the best one, in principle. If all the breakers were to trip simeltaneously (as said in a bus zone fault) they would not be ever reclosed simeltaneously. The spring charging occurs when the breaker is closed giving energy storage for one more trip, reclose and trip sequence. If at that time the spring is not recharged the breaker cannot be reclosed. This is for truck-typr gear in my experience, other types may differ.
Therefore the situation of all the charging motors running at the same time is unlikely, unless someone has switched off the DC supply and put it back on, has happened.
rasevskii
RE: DC or AC Spring Charging Motor
http://www.pnu-power.com/
RE: DC or AC Spring Charging Motor
RE: DC or AC Spring Charging Motor
For GIS, I would like separate it in the wiring from trip and control, separated cable from distribution board is used too..
For DC consumption, always calcualted worst case, 87B/BBP operated on all zones, and trip coil 1 and trip coil 2 on the same battarey and all charging motors start in the same time.
wort case is worst case
RE: DC or AC Spring Charging Motor
Hand charging a medium voltage breaker takes a fair amount of cranking, but hand cranking three 230 kV mechanisms will take quite a long time.
In sizing the battery and cabling voltage drops, I would start by assuming that they would all operate at the same time unless you have lockouts or other interlocks to prevent it. It may not happen often, but we have had a few different odd circumstances that had several or all the MV breakers in a lineup close at approximately the same time. When looking at voltage drop, remember that all the trip coils could be trying to operate while there are motors charging.
The battery charger would be sized to recharge the battery in a reasonable period, with the momentary peak load being supplied by the battery.
RE: DC or AC Spring Charging Motor
David Castor
www.cvoes.com