Solenoid Coil Whine / Resonance (Undervoltage Release Coil of Circuit Breaker)

[Keegan Howe]

Does anyone know as to whether there is a means to reduce the resonance noise produce from a AC solenoid (in this particular case the solenoid is a undervoltage release coil installed in a circuit breaker). I have been told by the manufacture that the coil is 240Vac 50Hz rated and that the noise is normal which I question. I have measured the power supply voltage and it is 244Vac at 50Hz.

Please see link for video of the noise produced by the solenoid.

Link

 

[ScottyUK]

Sounds / looks like the moving armature isn't cleanly mating with the fixed yoke, and there's an air-gap which allows a little vibration due to the AC supply. When you apply a little pressure it quietens down because you're damping out the vibration. I don't see it as a big problem - and it's by no means uncommon in contactors - but I can understand why it has been questioned. Not much you can do, unless you fancy stripping down the UVR to component level and using a surface grinder to very carefully true up the mating faces of the armature and yoke. Get this wrong and you could ruin the UVR, so think carefully before attempting this.

 

[itsmoked]

It's not resonance it's, as Scotty said, the armature not seated fully. Either the mating faces are deformed, there is some debris in between the faces (it can be very little), or (most likely) the secondary assembly mechanisms are out of spec and not allowing the armature to fully 'seal'. I would NOT put that into service. I have seen coils that make that amount of noise melt. This is because if the armature in not fully seated the coil is drawing more current than designed for as the maximum inductance is not being reached when the armature is not fully seated.

Keith Cress
kcress -

http://www.flaminsystems.com