Washing Machine Tripping RCD

billy_beckham · 30-10-2014 8:24pm #1

Hi All,

Looking for some help, washing machine tripping RCD. Narrowed it down to the main motor (unplugged it from control module and nothing popped

)
So heres the question, could worn carbon brushes cause RCD to trip? Not at machine so can not check condition of them now. Machine is approx 6 years old so they probably are worn and just occured to me that they could be the issue. Not much experience with these so throwing it out to the experts!

Advice much apprieciated!

Sleeper12 · 30-10-2014 9:00pm

billy_beckham wrote: »

Hi All,

Looking for some help, washing machine tripping RCD. Narrowed it down to the main motor (unplugged it from control module and nothing popped )
So heres the question, could worn carbon brushes cause RCD to trip? Not at machine so can not check condition of them now. Machine is approx 6 years old so they probably are worn and just occured to me that they could be the issue. Not much experience with these so throwing it out to the experts!

Advice much apprieciated!

Worn carbon brushes never cause RCD to trip. There are several parts that can cause it to trip. The most common is the element or pump but never the brushes

billy_beckham · 30-10-2014 9:15pm

Cheers for that. Its deffo the pump, with it plugged into control panel the rcd trips within 2 seconds, unplugged the program goes through the motions..

I was just querying the brushes as i read on another forum they were a possiblity...

Thanks again..

Sleeper12 · 30-10-2014 9:19pm

billy_beckham wrote: »

Cheers for that. Its deffo the pump, with it plugged into control panel the rcd trips within 2 seconds, unplugged the program goes through the motions..

I was just querying the brushes as i read on another forum they were a possiblity...

Thanks again..

If the brushes are worn there is no electric contact to the motor. It's very possible you need to replace the motor

Bruthal · 30-10-2014 10:05pm

I wouldn't think the pump motor has brushes. They are usually shaded pole motors. Worn brushes wouldn't be likely to cause that anyway.

Might be a dribble of water leaking from the pump onto terminals or similar.

mikeyjames9 · 30-10-2014 10:43pm

billy_beckham wrote: »

Cheers for that. Its deffo the pump, with it plugged into control panel the rcd trips within 2 seconds, unplugged the program goes through the motions..

I was just querying the brushes as i read on another forum they were a possiblity...

Thanks again..

are you saying main motor or drain pump

Zimmerframe · 30-10-2014 10:47pm

billy_beckham wrote: »

Hi All,
Narrowed it down to the main motor

billy_beckham wrote: »

Its deffo the pump..

Which is it ?

mikeyjames9 · 30-10-2014 10:50pm

could even be a wire snagged on the loom to drain pump or motor

i wouldn't think drain pumps themselves give much trouble...they're only 2-wire

if it was main motor i would test the cable and check brushes...motor itself can be tested if you know what to check

billy_beckham · 30-10-2014 10:53pm

Apologies for my mistake...main drive motor is the problem....and from the Bosch website it appears it does have carbon brushes..see attached.

billy_beckham · 30-10-2014 10:58pm

mikeyjames9 wrote: »

could even be a wire snagged on the loom to drain pump or motor

i wouldn't think drain pumps themselves give much trouble...they're only 2-wire

if it was main motor i would test the cable and check brushes...motor itself can be tested if you know what to check

6 cables going to motor, using a multimeter none are shorting to earth. I presume the 6 are the ends of 3 windings...getting approx 15ohms on 1 and about 2ohms on other 2...maybe burnt out. As said earlier not at machine now so can't check anything else....

mikeyjames9 · 30-10-2014 11:09pm

billy_beckham wrote: »

6 cables going to motor, using a multimeter none are shorting to earth. I presume the 6 are the ends of 3 windings...getting approx 15ohms on 1 and about 2ohms on other 2...maybe burnt out. As said earlier not at machine now so can't check anything else....

field, armature and tacho

you can check IR with a megger but not the tacho

Micky 32 · 30-10-2014 11:17pm

Sleeper12 wrote: »

Worn carbon brushes never cause RCD to trip.

They actually can sometimes, especially sensitive trip switches but not very common though. Called to one last Saturday, was arcing and caused the trip...

I have seen this problem a few times on the Bosch and the motor is usually the culprit, you could always take it apart and give it a good clean from the carbon dust.

mikeyjames9 · 30-10-2014 11:21pm

Micky 32 wrote: »

They actually can sometimes, especially sensitive trip switches but not very common though. Called to one last Saturday, was arcing and caused the trip...

I have seen this problem a few times on the Bosch and the motor is usually the culprit, you could always take it apart and give it a good clean from the carbon dust.

not too familiar but i certainly wouldn't rule it out

first thing to check anyhow

billy_beckham · 30-10-2014 11:42pm

mikeyjames9 wrote: »

field, armature and tacho

you can check IR with a megger but not the tacho

I stand corrected..

Micky 32 wrote: »

They actually can sometimes, especially sensitive trip switches but not very common though. Called to one last Saturday, was arcing and caused the trip...

I have seen this problem a few times on the Bosch and the motor is usually the culprit, you could always take it apart and give it a good clean from the carbon dust.

Think i'll get a set of brushes and give it a blow out and see...worth a shot!

Thanks for the advice

Bruthal · 31-10-2014 6:43am

mikeyjames9 wrote: »

field, armature

Yea they are brought out separate to enable reversing etc

Bruthal · 31-10-2014 6:45am

billy_beckham wrote: »

Apologies for my mistake...main drive motor is the problem....and from the Bosch website it appears it does have carbon brushes..see attached.

Its not in doubt that the drive motor has brushes.

billy_beckham · 31-10-2014 5:08pm

Well i got new brushes, put them in, blew out around the armature etc and plugged it in and.........it still tripped!:o

Thanks anyway..

Micky 32 · 31-10-2014 6:50pm

billy_beckham wrote: »

Well i got new brushes, put them in, blew out around the armature etc and plugged it in and.........it still tripped!:o

Thanks anyway..

I'm afraid new motor or new machine, Bosch motors are quite saucy model dependent, might be lucky on Ebay for a good second hand one.

The Red Ace · 01-11-2014 1:04am

the reason the armature shorted is the brushes when worn let the copper feed wire touch the comm of the armature causing it to short, shouldnt happen but Bosch in their wisdom have made them like this for years, usually only happens only after trying the w/m several times, so beware if the machine displays error f21 or has no motor action dont keep trying, check the c/bs

Sleeper12 · 01-11-2014 9:10am

The Red Ace wrote: »

the reason the armature shorted is the brushes when worn let the copper feed wire touch the comm of the armature causing it to short, shouldnt happen but Bosch in their wisdom have made them like this for years, usually only happens only after trying the w/m several times, so beware if the machine displays error f21 or has no motor action dont keep trying, check the c/bs

Its still tripping with new brushes so this is not why it was tripping (as I said earlier in the thread)

The Red Ace · 01-11-2014 1:37pm

Sleeper 12, the damage has already occured, a new set of brushes wont rectify the problem

Bruthal · 01-11-2014 3:25pm

The Red Ace wrote: »

the reason the armature shorted is the brushes when worn let the copper feed wire touch the comm of the armature causing it to short, shouldnt happen but Bosch in their wisdom have made them like this for years, usually only happens only after trying the w/m several times, so beware if the machine displays error f21 or has no motor action dont keep trying, check the c/bs

Why do you think the armature is shorted? I doubt that myself. Even if the wire on end of brushes touches the commutator, how will that short anything, when the whole idea of carbon brushes is to make a connection from the wire to the commutator copper strips.

The fault is causing an RCD trip, which does not require any damage level short circuits. Likely an earth fault due to water leak, or insulation problem in the motor or its wiring, assuming it is the motor at all.

Sleeper12 · 01-11-2014 3:38pm

The Red Ace wrote: »

Sleeper 12, the damage has already occured, a new set of brushes wont rectify the problem

You are way off the mark I'm afraid. I guarantee there was lots of carbon on the brushes when OP changed them. They didn't need to be changed at all. He just did because if it worked it was a cheap fix.

I have seen lots of motors trip the breaker (I change 5 or 6 motors per week) but I've never, ever come across the breaker tripping because of worn or new carbon brushes

billy_beckham · 01-11-2014 6:09pm

Bruthal wrote: »

Why do you think the armature is shorted? I doubt that myself. Even if the wire on end of brushes touches the commutator, how will that short anything, when the whole idea of carbon brushes is to make a connection from the wire to the commutator copper strips.

The fault is causing an RCD trip, which does not require any damage level short circuits. Likely an earth fault due to water leak, or insulation problem in the motor or its wiring, assuming it is the motor at all.

As said in initial post when motor is unplugged nothing trips!!

Sleeper12 wrote: »

You are way off the mark I'm afraid. I guarantee there was lots of carbon on the brushes when OP changed them. They didn't need to be changed at all. He just did because if it worked it was a cheap fix.

I have seen lots of motors trip the breaker (I change 5 or 6 motors per week) but I've never, ever come across the breaker tripping because of worn or new carbon brushes

There was approx 1/2" of carbon on them alright....worn but not down to the wire..

Bruthal · 01-11-2014 6:49pm

billy_beckham wrote: »

As said in initial post when motor is unplugged nothing trips!!.

I'm not disputing its likely the motor. RCD trips can sometimes occur when the fault is somewhere other than in the item that appears to trip it though.

It likely is an earth fault with the motor in this case though.

The Red Ace · 01-11-2014 7:33pm

Folk and especially Sleeper 12 I have worked on these machines for decades so i think i know what causes them to go wrong , the wire attached to the brush is quite thick, when the brush wears down the wire is long enough to touch between two strips of the comm to cause the insulation of the armature to break down if the operator keeps trying it to run , doesnt happen with most of the other brush sets, Rarely have i seen these motors to give trouble unless the drum is heavily overloaded or something has cracked the outer tub and leaks from the two hoses attached are virtually nil in my experience, B/Beckham I have plenty of these motors should you care to pm me

Sleeper12 · 01-11-2014 7:45pm

The Red Ace wrote: »

Folk and especially Sleeper 12 I have worked on these machines for decades so i think i know what causes them to go wrong , the wire attached to the brush is quite thick, when the brush wears down the wire is long enough to touch between two strips of the comm to cause the insulation of the armature to break down if the operator keeps trying it to run , doesnt happen with most of the other brush sets, Rarely have i seen these motors to give trouble unless the drum is heavily overloaded or something has cracked the outer tub and leaks from the two hoses attached are virtually nil in my experience, B/Beckham I have plenty of these motors should you care to pm me

If you read the ops comments you'll see that the brushes were not worn down. Even if they were they will not cause it to trip

OP has said brushes not worn down. Look for another tree to bark up. :-)

Bruthal · 01-11-2014 7:47pm

The Red Ace wrote: »

Folk and especially Sleeper 12 I have worked on these machines for decades so i think i know what causes them to go wrong , the wire attached to the brush is quite thick, when the brush wears down the wire is long enough to touch between two strips of the comm to cause the insulation of the armature to break down if the operator keeps trying it to run , doesnt happen with most of the other brush sets, Rarely have i seen these motors to give trouble unless the drum is heavily overloaded or something has cracked the outer tub and leaks from the two hoses attached are virtually nil in my experience, B/Beckham I have plenty of these motors should you care to pm me

So brushes only contact a single strip on the commutator at a time?

Bruthal · 01-11-2014 7:54pm

Sleeper12 wrote: »

Even if they were they will not cause it to trip

Indeed. Two or 3 segments of the commutator next to each other being shorted simply eliminates a tiny sector of windings from the equation at any given time.

Quite how that causes insulation to fail on the windings is a mystery.

Washing Machine Tripping RCD

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