circuit breaker coil protection

[Kataeb]

we get frequent damage of the coils of our circuit breakers. our power supply is not really clean, sometimes running on generators. how can we protect the coil?

3vl5763-1te46-2je1 , circuit-breaker vl 630n standard breaking capacity icu=55ka / 415 v ac 4 pole, line protection electronic trip unit etu20, lsi in=630a, rated current ir=252-630a, overload isd=1,5to9xir, ii=10xin short-circuit n unprotected, UNDERVOLTAGE RELEASE 380 - 415 V AC, auxiliary/alarm switch kit 2hs(1no+1nc)+1as(1no)

 

[jraef]

You have an Under Voltage trip coil which is the only "copiul" on your circuit breaker. That means it is energized at all times and trips the breaker if it ever loses power. If the coils are burning out, it is a manufacturing defect, they are EXPECTED to be energized constantly without failing. You should contact Siemens about it.

Why are you using an Under Voltage trip coil by the way?

 

[Kataeb]

we are you using an Under Voltage trip coil, to avoid energizing the cabinet immediately when power comes back, because usually it does not do it in a smooth way, and sometimes goes off and on few times consecutively...

 

[jraef]

Ok, that's exactly what they are for. So your issue is likely with Siemens having defective coils then, not with something more you need to do, because you are using them exactly as they are intended. You need to involve them, they need to know. They are not known for making junk, so this may be a looming manufacturing process or testing failure that they need to address. Sometimes on things like this, the only way they find out is from people complaining.

One qualification however; the breakers are rated for 40C operation, but I think perhaps the UV coils are rated for 25 or 30C max ambient. If your internal enclosure temperature is higher, that may be a root cause of the failures. Look up the operating specs of the UV coils, I'm going by memory here and I have killed a lot of brain cells since I left Siemens.

 

[NetNathan]

There were a few CB mfg that did not make very UV trip coils on the older breakers. Square D used to have terrible UV coils. They were only good for about 10 trips then died.