Bench drill trips rcd.

[Bsmith]

My bench pillar drill often trips the rcd when I press the start switch, but not every time. It does not trip the mcb. Checked continuity with meter on the 13a plug but no short found, just normal motor resistance.
Common problem?

 

[rtbcomp]

You should be checking the resistance between live/neutral and earth with a proper insulation tester.

Is there an interference supressor in the circuit, sometimes they have a capacitor between neutral and live to earth, if this is leaking it could trip the RCD.

 

[123hotchef]

same thing was happening with our freezer yesterday plug it in a non rcd protected plug and it is fine

 

[rtbcomp]

same thing was happening with our freezer yesterday plug it in a non rcd protected plug and it is fine

Words fail me.

There's obviously a fault on the fridge (or the RCD) and you remove the protection.

 

[123hotchef]

ha ha it was for a day just got a nice new one

 

[dobbslc]

What!
You mean that old rewireable fuse with 2 bits of 30amp wire in it won't blow when the fridge is passing 5amps down to earth? Or up someone's arm!

 

[Bsmith]

You should be checking the resistance between live/neutral and earth with a proper insulation tester.

Is there an interference supressor in the circuit, sometimes they have a capacitor between neutral and live to earth, if this is leaking it could trip the RCD.

Don't have an insulation tester, elect's don't want to hear of extra work round here.
I'll follow the wiring through to the motor tomorrow, see if I can find a capacitor.
Nu-way 5/8" chuck capacity bench drill, made in Taiwan. I bought it in 1980 via Exchange and Mart. Has been ok.

 

[123hotchef]

That's alright then, you only exposed other house members to a potentially live large lump of metal for a short time...

it was still on a 16amp mcb so not all bad just not rcd protected

 

[rtbcomp]

it was still on a 16amp mcb so not all bad just not rcd protected

You're missing the point.

An RCD trips when current is escaping to earth, possibly through a person.

A 16A MCB gives no protection at all, apart from to the wiring to the wall socket.

 

[123hotchef]

ok i got it! doh

 

[Bsmith]

Bigger job than I thought. Checked wiring and switch, couldn't find fault. Took motor apart and found burned windings. (photo soon). Think it will be the start windings, ones nearest the rotor. Got another motor and adapting it to fit.

 

[Bsmith]

Can't say I remember working the drill too hard and do not recall any burning smell, but there we have it, motor knacked. Are they the start windings that are blacknend?

 

[Bsmith]

Adapting another motor to fit, shaft too short so made an adaptor.
Hope the original shaft is strong enough to support the adaptor and pulley. Better than having no motor.