Vacuum Circuit Breaker Trip Circuits
Vacuum Circuit Breaker Trip Circuits
(OP)
We're about to replace old oil CB with new GE-VAC CB. Control dwgs for new CB shows two outputs to each of Remote Trip Ckt. and Remote Close ckt. Any advice on how best to utilize each of these 4 ckts (to the two remote trip and two remote close ckts)?
In the old breaker we had a Low Pressure Alarm ckt., what the equivelant alarm should be for the new VAC CB?
Thanks folks for your help and feedback
best regards,
In the old breaker we had a Low Pressure Alarm ckt., what the equivelant alarm should be for the new VAC CB?
Thanks folks for your help and feedback
best regards,






RE: Vacuum Circuit Breaker Trip Circuits
I'm not quite clear on the remote close and trip question. You can connect whatever you want to operate the breaker to these inputs.
Does the new vacuum breaker have dual trip coils by chance?
RE: Vacuum Circuit Breaker Trip Circuits
Probably there will be more than one close coil and trip coil. You can use it for whatever you want, local switching, remote switching, auto reclose etc. for the closing coils and local switch-off, remote switch-off, normal tripping, back-up tripping etc. for the tripping coils.
Are you changing your total electrical installation (new braker, control circuits, tripping circuits etc), or just the breaker?
RE: Vacuum Circuit Breaker Trip Circuits
Does the OP mean “two inputs to each pair of trip and close solenoids”? [It is routine to furnish multiple {more than two} 52a/52b “output” contacts in modern MV/HV circuit breakers.]
As for trip/close solenoid coils, it could be the vendor had an extra breaker abandoned from an earlier order with special-order dual-trip/-close coils that he just happened to unload on you “at no extra charge.”
RE: Vacuum Circuit Breaker Trip Circuits
Low pressure alarm trip contacts possibly irrelevent in the VCB circuit breaker .
Other available contacts can be used in the modified trip circuit for VCB panels
RE: Vacuum Circuit Breaker Trip Circuits
The trip coil ckt. has two 'a' contacts in series with it, these we're taking to SCADA, another paraller trip ckt. has 'b' contact which is what confusing me what to do with it!!!!!!!!!
As for the closing coil ckt., one O/P we're taking to a GE-reclosing relay (we'll operate the CB on 3-reclose attempts before lock-out), the other we decided to take to SCADA.
RE: Vacuum Circuit Breaker Trip Circuits
Are you saying that there is a second trip coil with a "b" contact in series with it? This makes no sense because then the trip coil would only be energized if the breaker is already open.
RE: Vacuum Circuit Breaker Trip Circuits
But close coils usually have "b" contacts in series for exactly the same reason that the trip coil has "a" contacts in series.
The relay contacts that make to trip and close the breaker could very well be unable to break the coil circuit and depend on the heavier "a" and "b" contacts to do the circuit breaking.
RE: Vacuum Circuit Breaker Trip Circuits
Does anyone know what does the R and G means in the 89 Control Switch Circuit (Selector Switch)??
RE: Vacuum Circuit Breaker Trip Circuits
RE: Vacuum Circuit Breaker Trip Circuits
The breakers we use have a Trip Circuit Supervision (TCS) terminal.
A simple explantion is from the TCS terminal there is one 'b' contact direct to the trip coil. There is also a parallel circuit through two 'a' contacts in series to the trip coil.
There is a terminal between the two 'a' contacts which the trip contact is connected to.
The TCS relay is connected to the DC +ve on one side and to the TCS breaker terminal on the other. The relay remains energised while everything is healthy.
I would guess that this is what it is for.
RE: Vacuum Circuit Breaker Trip Circuits
Thanks so much, you got it right, I thought they would label the circuits (T=Trip, C=Close), instead they labeled them G=Green, R=Red, as you wisely guessed.
DiscoP,
That is very much what we have on the VAC-Breaker, my guess would be the two 'a' series contacts serve as back-up to one another in case one of them gets 'sticky' and doesn't open in timely manner (one of them operating is sufficient if the other gets stuck!!). That's also what DavidBeach hinted to in his message.
In my case, we're using the other 'leg' for the trip Ckt. for 89 Manual Trip/Close in the control house.
Thank you all again for your feedback and help
RE: Vacuum Circuit Breaker Trip Circuits
The two 'a' contact don't really back each other up.
The trip circuit is a trip contact in series with an 'a' contact in series with the trip coil.
The second 'a' contact is to keep the trip circuit supervision relay picked up when the breaker is closed.
If you don't use a trip cicuit supervision relay, then only one 'a' contact is required in the trip coil circuit (and no 'b' contacts).
I hope this can be followed - it is difficult to clearly explain without a drawing !
RE: Vacuum Circuit Breaker Trip Circuits
Thanks for clearing the function of the two 'a' contacts, it didn't seem to make any sense to me before you explained it.
in the old breakers, the two 'a' contacts were in series and we did have access to the node between them, we took the first 'a' contact to a remote trip ckt and the second 'a' contact to manual trip switch.
It seems in the new breakers, we won't have access to the first 'a' contact as they're connected together internally and the terminal connecting them is not accessible, do you think it will be a problem if we take the two ckts I described earlier off the second 'a' contact alone??
Thanks again
RE: Vacuum Circuit Breaker Trip Circuits
In our breakers we have the control trip contacts in parallel - then to the same 'a' contact - then on to the trip coil.