Is transformer hum normal or a fault?

Forums › Off topic › Is transformer hum normal or a fault?

scuwp

3885 posts

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#288588 10-Jul-2021 19:43

Google isn't helping.

We have a new garage door opener installed recently. The unit emits a distinct low level hum/buzz noise, and and a slight vibration can be felt when you put your hand on the cover. Clearly coming from the transformer inside.

Online searches range from "that's normal" to "imminent failure". I am particularly sensitive to the noise so not sure if I am overreacting? Noise aside I am concerned about failure and fire risk.

The installer has been great to deal with and it comes with a 5 year warranty so no issues at all getting after sales support. They have been back to check and tighten the fittings but it didn't make any difference. They don't seem too concerned.

Thanks.

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snnet

1410 posts

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#2742266 10-Jul-2021 19:45

Normal if its a transformer, not good if its a contactor/relay

In reality all they would probably do is loosen or tighten the screws holding the transformer as you've said already

I typically loosen the fixing screws slightly on alarm panel transformers because they can generate quite a bit of noise thru the wall they are attached to

kiwiharry

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#2742279 10-Jul-2021 21:35

snnet:
I typically loosen the fixing screws slightly on alarm panel transformers because they can generate quite a bit of noise thru the wall they are attached to

Thanks for that tip. Yeah transformer in our alarm panel makes quite a bit of a hum and we have a bathroom on otherside of the wall. Bit annoying when you are sitting there taking some time out 😂

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snnet

1410 posts

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#2742281 10-Jul-2021 21:44

you can also insert slips of rubber between the transformer and the panel -- bear in mind the panel tamper may be active so you might have to bypass that first to stop it going off :)

Rikkitic

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#2742302 10-Jul-2021 23:37

The transformer hums because it is made up of metal plates and a rapidly alternating magnetic field from the AC current. Humming is normal. How audible it is depends on the construction of the transformer and the load on it. The hum can be irritating but is not in itself an indication of anything wrong.

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jpoc

1043 posts

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#2742328 11-Jul-2021 07:37

Why would the transformer need to be powered up the whole time? Is that not a constant power drain?

Bung

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#2742335 11-Jul-2021 08:34

The radio for the remote control would have to be on standby. That shouldn't take much power. I don't think I've ever noticed any noise coming from an idle door opener. Occasionally capacitors can also hum.

neb

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#2743438 12-Jul-2021 21:11

snnet:
Normal if its a transformer, not good if its a contactor/relay

You may be able to replace it with an impregnated transformer that's designed to minimise hum. These were used in better-quality bedside clock radios some years ago, for example.

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Geektastic

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#2743452 12-Jul-2021 22:04

If it is in a Naim amplifier, normal. We need to sell you a special power supply to deal with that sir...

Fred99

13684 posts

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#2743503 13-Jul-2021 09:42

Geektastic:

If it is in a Naim amplifier, normal. We need to sell you a special power supply to deal with that sir...

Really? Is that some kind of woo-science based "power conditioner" for the golden ears brigade - or a separate PSU providing DC to the amps?

As for the OP's noisy door opener, despite what the supplier claims, I suspect it could be faulty but the supplier won't want to know about "a bit of transformer hum" if the motor is still working OK, as it's a dead loss, they'll throw it in a waste skip, not much chance of a claim against the chinese maker, that's probably far more hassle than it's worth.

Transformers all hum to some degree. Generally the more saturated the core the louder, but in standby mode there should be almost no current draw at all. Faults could cause excess current draw, that could also be a fire risk (unlikely but possible).

There's probably spec on power use for the unit, maximum in use and standby, if you don't have gear to measure it (a wifi smart plug would be an easy and cheap and safe way) then if the case is warm when it's not been in use for an hour or so, something is probably wrong.

If it's not drawing more power than spec but quite noisy, then it's probably just loose windings or laminations in the transformer core, that's still a "fault" and the supplier should fix or replace it. There are dozens of devices with transformers around our house, none of them make any noticeable hum.

tripper1000

1617 posts

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#2743656 13-Jul-2021 14:08

Transformers do hum quietly in normal operation, but can be made quieter if the mfg cares to. If the hum suddenly gets louder it can be a sign something has changed within the unit.

Does the unit have a metal case? With metal cased appliances, the transformer itself can be quiet, but the magnetic leakage (which oscillates north-south 50x per second) can induce vibrations in the appliance case so it becomes audible. As alluded to above, adding mass or pressure to the offending panels can reduce the vibration which reduces noise.

Tinkerisk

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#2743683 13-Jul-2021 15:09

If it is too loud, one could think about a replacement of the transformer by a ferrite ring core type one. But it depends of the mechanical construction.

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mattwnz

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#2743685 13-Jul-2021 15:11

I have never noticed a garage door opener hum. Brand?

hsvhel

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#2743755 13-Jul-2021 16:11

is the transformer inside the door opener module?

I have a Garador unit and there is no sound at all

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scuwp

3885 posts

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#2743780 13-Jul-2021 19:33

Thanks all. I guess the main concern alleviated is that it's unlikely to explode into a ball of flames.

We had a Dominator but the motor burnt out (that's another story). Dominator had a 2 week wait for a new one, were charging a small fortune, and there were compatability issues with our older obsolete model.

We then got onto a local agent who installed Garador/Door Works (Aussie brand I believe). Great service, and worked well. No hum at this point. A few weeks later the LED light panel stopped working (the one that lights up the area) which was quickly resolved by replacing the main circuit board. When I looked at it, it was obvious that a component on the board had failed and burnt out. Then the hum started. They have been back and tried to 'quieten' it by making some adjustments to the fixings but it hasn't worked.

They have said they will replace it if we were still unhappy. I guess I was wondering if I was overreacting. or we should ask for a new one. I am sensitive to low level sounds.

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hsvhel

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#2743781 13-Jul-2021 19:36

^^Same, low humming i seem to pick up way to easily.

Might be worth trying the transformer change if they are open to it?

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