Forum Discussion

peaeye1's avatar
peaeye1
Explorer
Jul 21, 2016

humming/ buzzing noise

There is a humming/ buzzing sound coming from the transfer switch.The unit is prepped for a generator, but one is not installed.It has been making this noise for at least a couple of months.I have pulled the cover on the switch box and everything "looks" ok. The box is not hot to the touch and no smells like wiring is getting too hot.This is on a winnebago 5th wheel using 50 amp service.Everything electrical works fine on the trailer.The sound can't be heard inside the unit, only when accessing the basement area.
I thought I would run this by the folks on here before calling the dealer tomorrow.
  • john_bet's avatar
    john_bet
    Explorer II
    Jul 22, 2016
    In my 21 years as an industrial electrician with experience with the same contactors as these transfere sw's, most of the time they were dirty or the armature was rusty so that the two parts would not come completely together. The dirt and rust impeded the flow of the magnetic field between the two parts causing them to hum/chatter. The fix was a complete disassembly and a good cleaning.
  • garyemunson's avatar
    garyemunson
    Explorer II
    Jul 22, 2016
    The buzz is caused by the two pieces of metal that are pulled together by the magnetic coil and pull the contacts together. Generally dust/dirt keeping them from seating against each other totally. As said, blow the relay out with compressed air or, if you are mechanically inclined, dismantle it and clean it. If it's older, you'll find the surfaces get a beat-up look and this can be fixed by smoothing them off by putting coarse sandpaper on a flat surface and rubbing the part on it. Takes some elbow grease as the surfaces 'work harden' from the banging together. Or...you could just buy a new relay!
  • 12th_Man_Fan's avatar
    12th_Man_Fan
    Explorer
    Jul 21, 2016
    Mine has been buzzing since brand new. I called the MFG. and they said this was normal.

    I also have a generator prep with no generator.
  • STBRetired's avatar
    STBRetired
    Explorer
    Jul 21, 2016
    Sometimes the relay coils will hum. Not a big deal as long as that is what is making the noise. Disconnect all power and blow ATS out with compressed air. Seems to help quiet mine down when it starts to hum. If it REALLY bothers you, you can replace the relays with ones that are designed to not hum, but now you are talking several hundred dollars and might as well just buy a new ATS with the no-hum relays.
  • Valkyriebush's avatar
    Valkyriebush
    Explorer II
    Jul 21, 2016
    No big deal. Could be just dust. Loose connection. Since you checked it and not hot or burning smell I wouldn't be so fast to shut it down or buy a new ATS. If it makes you feel better. Mines been humming on and off for years. Got use to it.
  • peaeye1's avatar
    peaeye1
    Explorer
    Jul 21, 2016
    Old-Biscuit wrote:
    Either wiring terminals are loose
    OR
    Relay contacts are worn....not making FULL surface contact.
    They are arching and will fail


    Thanks, I will turn off power to the unit and tighten connectors. This unit is less than a year old.Odds are loose connections.
  • Old-Biscuit's avatar
    Old-Biscuit
    Explorer III
    Jul 21, 2016
    Either wiring terminals are loose
    OR
    Relay contacts are worn....not making FULL surface contact.
    They are arching and will fail
  • rockhillmanor's avatar
    rockhillmanor
    Explorer
    Jul 21, 2016
    My humming buzzing was a bad converter. You could barely hear it but the sound was there in the coach. Took me awhile to track it down. Since the converter only turns on when needed.

    When we opened the old converter one capacitor was shot. Almost literally, it looked like someone shot it with a 22!

    And BTW with only one capacitor working it managed to totally fry my coach battery by emitting too much voltage. Go figure.

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