Motor trips RCB

[caskwith]

Ok so I bought a second hand industrial sewing machine motor (brushed). I also picked up one of the cheap chinese motor speed controllers with the intention to put together either small high speed buffer or sander type thing, not sure yet but it was cheap so... you know   

Anyway motor arrives and I perform the test wiring and as always I plug itto one of those RCB's you use for power tools when outdoors etc.
Motor runs great for a minute or two then trips the RCB. Reset RCB and it runs for another 10-15secs before it trips again.
I reckon it could be the cheap motor controller (£2 ebay jobbie) so I take that off and wire the motor directly into the mains. Switch on and it runs full pelt of course (fast!) but the same thing happens, runs for a little while then trips.

After it tripped I checked the motor, and ran it with the brush covers removed so I can see inside. Slight arcing of brushes when running but nothing crazy, no smell, no magic smoke and the motor is not even warm when it trips.

Any ideas what is going on here?

[awemawson]

Leave it in the airing cupboard for a few days to drive out any moisture

[caskwith]

I don't think moisture would be a problem, it has had over a week sat in the workshop while I waited for the other bits to arrive and my workshop is not damp at all.

[lordedmond]

Bet it got a suppression cap in it
The are a three legged thing one to each brush holder and the third to earth ( case )

They go leaky and often trip RCD ,s


Stuart

[caskwith]

Bet it got a suppression cap in it
The are a three legged thing one to each brush holder and the third to earth ( case )

They go leaky and often trip RCD ,s


Stuart

Yes it does, I spotted that inside when I was checking the brushes. Can I do anything about that? I know I removed the supression cap on a sewing machine as it was causing a short. Will it be safe to remove this one and will it run without?

[lordedmond]

In short yes you can dump it will not effect the motor at all

Stuart

[awemawson]

Just your neighbours will love you even more when you run it and they are watching the telly 

[caskwith]

Well it worked

They don't complain when I run any of the other tools and I am sure plenty of them put out more noise than this motor will. In fact it hardly had any effect on the radio that was right next to it, my cordless drill makes more of a crackle.

[lordedmond]

Well I only said the motor would be OK, not about anything else

Yes I do know it could but I think the digital televisions are a bit more tolerant

But I bet my  old 3kw SSB amp would see them off fit use to modulate the lights with the load and flory tube would light up in the garden and that was on top band 

Not to mention the 23 cm amps microwave birds anyone ERP was in the order of 20kw

Those were the days GPO nearly set up camp outside

Anyway glad you have it sorted ,you can buy them from Mouser. Or Farnel if you need to

Stuart

[awemawson]

Just wait until I get round to re-commissioning my 100kVA Induction Furnace, that'll stir 'em up 

..... oh .... we don't HAVE neighbours   

... ok I'll get 'em dropping the line voltage as the overhead wires call on us first then 1/2 mile to nearest neighbour - I'll make their lights flicker