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Topic Title: Humming RCD
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Created On: 21 September 2017 10:18 PM
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 21 September 2017 10:18 PM
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Nospark

Posts: 195
Joined: 05 October 2013

I have come across a 63A RCD(2 pole, single phase) that hums when loaded with about 1.5kW's of inductive loads, but not when minimally loaded with non inductive loads. What causes this?
I couldn't try different loads to see what happens.
 21 September 2017 11:11 PM
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mapj1

Posts: 9679
Joined: 22 July 2004

Well, inside the RCD you have a magnetic core about which L and N are wrapped, in a way that should cancel, unless electrons go off on the live, and fail to come back via the neutral wire.If the winding on the core, or the support for part of the mechanism is loose, then it may vibrate in time with the AC, if there is an imbalance that is not large enough to trip it , but a significant fraction of that needed to pull the contacts over the point of no return.
I have also had MCBs humming when supplying loads that draw a non-sinewave current, such as lamp dimmers and some switch mode supplies.
Its probably not serious.


EDITED to correct some utter gibberish that I had not intended to post, apologies.
(I am in the habit of drafting responses over a protracted period, and only sending them when ready. The half cock state can be a little embarrassing.)

-------------------------
regards Mike


Edited: 22 September 2017 at 01:31 PM by mapj1
 22 September 2017 12:03 AM
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kellyselectric

Posts: 191
Joined: 22 July 2016

Maybe it don't know the words!! Sorry!
 22 September 2017 01:26 AM
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MWalker86

Posts: 99
Joined: 05 June 2017

*snigger*
 22 September 2017 08:33 AM
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Nospark

Posts: 195
Joined: 05 October 2013

Lol
 22 September 2017 09:05 AM
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Thripster

Posts: 806
Joined: 22 August 2006

I have come across this phenomenon before and discovered that it was due to the tails not being properly secured in the device.


Regards
 22 September 2017 05:52 PM
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Nospark

Posts: 195
Joined: 05 October 2013

That was my first thought, but they were secure.
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