7.2kV Circuit Breaker Close Blocking Switch
7.2kV Circuit Breaker Close Blocking Switch
(OP)
We have 7.2kV, 1200A, ABB Advac Circuit Breaker feeders. In the associated breaker internal wiring diagram, we observed that there is a "close blocking switch" in series to the closing coil/anti-pump device.
I would appreciate if anyone who had experience on these breakers share their knowledge on how this switch operate and when it operates?
Furthermore, the closing coil (52X) have 52b in series to it, does this mean that an external maintained closing input can be wired to it?
The closing circuit has some kind of rectifier (4 diodes) on its input terminal. I'm still trying to contact the manufacturer for this..but a heads up opinion is appreciated.
Thanks and regards...
I would appreciate if anyone who had experience on these breakers share their knowledge on how this switch operate and when it operates?
Furthermore, the closing coil (52X) have 52b in series to it, does this mean that an external maintained closing input can be wired to it?
The closing circuit has some kind of rectifier (4 diodes) on its input terminal. I'm still trying to contact the manufacturer for this..but a heads up opinion is appreciated.
Thanks and regards...






RE: 7.2kV Circuit Breaker Close Blocking Switch
RE: 7.2kV Circuit Breaker Close Blocking Switch
The 52b contact is to make sure that the close signal is removed from the coil once the breaker closes.
The diode bridge allows them to use a DC close coil on an AC close breaker. Have never liked it because it is another component to fail...and they do!
Electrically you could use a maintained close signal however the breaker would reclose as soon as it is tripped with the obvious consequences. Older style reclosing relays are often configured this way.
Alan
RE: 7.2kV Circuit Breaker Close Blocking Switch
RE: 7.2kV Circuit Breaker Close Blocking Switch
RE: 7.2kV Circuit Breaker Close Blocking Switch
Our circuit breaker coil burned open. ABB inspected it at site and the initial comment is that the breaker may have been subjected to continuous current flow.
I was wondering how will that gonna happen if there is a 52a contact that drops-out the coil after a succesful close.
Is it possible that these contact may have failed to open? If this is a possibility, what may caused it?
RE: 7.2kV Circuit Breaker Close Blocking Switch
As for the switches, yes they can go bad, become mis-aligned, or become loose in their mounts. Have seen all of the above.
Alan