how to test a motor

[clogs]

Hi, not strictley woodworking but associated.....
I have an as new washing machine...(literally just 5 cycles)....have known the machine from new....Mother inlaw.....
anyway......
plug it in switch on and straight away it trips the RCD......did this 3 times......
took off what panels I could to look for broken/chaffed shorted wires.....non found.....
so before the fourth try I unpluged the motor connections....now the RCD stays in.....
.......
have taken the motor off looking for burns etc.....found nothing.....no bad smells either.....
have tested with an ohm meter (not really sure what I'm looking for, the meter reads zero and beeps if the two probes are touched together) directley on the brush holders and no short, the figure on the meter was 4......
on the photo u will see the wire holder/connecter.....
so have tried the meter between each wire and earth and no dead short......all connecters read between 4 and 5......
what else can I look for.....
I do need another washing machine as the old one sounds like it ready to die.....
......
the red and the black wires go directley go to the brush holders...
2 yellows...is that a rev counter....?
the orange, blue and the 2 whites look like they go to extra windings.....
.........
lastley if I connected a live and neutral to the brush holders would that be ok.....?.....have heard they will spin up and destroy itself (over speed) because theres no load....

many thanks......

 

[guineafowl21]

The machine won’t activate the motor as soon as you switch on, so I would guess the tripping RCD (means either L or N leaking to earth) is further up the chain and disconnecting the motor was a red herring. A dicky motor would normally trip things at a certain stage of the cycle.

The yellow wires are a speedo, yes, and the extra ones are to do with speed/direction control. Don’t hook up the brushes to the mains! The stator windings also need power and it would rev itself to bits anyway.

1. With the machine switched on at its panel, but unplugged from the wall, measure resistance (highest range, 20M or whatever) between L-E and N-E of the plug. Don’t hold the probes in contact with your fingers, as you will interfere with the result.

2. Then follow the mains wires into the machine, through the interference filter, then on to the panel. Look for wetness/frayed or chewed wires, anything unusual.

3. Check the control panel board for same.

4. As best you can, inspect the wiring to heating element, sump pump, motor - everything you can find.

It only takes a tiny leak (around 30/1000s of an amp) to trip an RCD, and the effect is cumulative - many appliances might be leaking a bit, and the washing machine is the final straw. What else is plugged in to the same group? The tripped RCD will monitor all those circuits immediately next to it. Try unplugging some appliances in the same group.

 

[Spectric]

Hi

Washing machine motors can be complex, often noted by having many more connections than seem needed. Some have different windings for different cycles, some are electronicaly commutated and most are controlled electronicaly. The yellow wires on your motor provide RPM feedback so the controller can maintain the speed in closed loop control for the different cycles. You could remove the armature and clean the commutator and clean the gaps between segments but like most things these days it will be a new motor.

 

[clogs]

Ok, put the motor back in the machine and reconected the multi plug BUT with the heater disconected by bothe wires.....
it still trips...
but this time I stood by the fuse box and wifey turned on the machine.....
IT takes out the main incoming trip...so not a circuit but the total board.....
have checked all the wiring except taking off the machines programmer and alllooks well...
even cut the zip ties to get a better look....so the wiring harness was in my hand....

 

[Spectric]

If this worked in the MIL's but is tripping in your place then what is the difference in the two properties as far as the supply? The machine may be Ok, or possibly have high earth leakage that did not cause an issue in the MIL's.

 

[guineafowl21]

Maybe the MIL’s house is an older place with no RCD?

Can you disconnect the machine’s main board and see if it trips then? I can’t see how the motor would cause tripping when you just switch on at the wall.

 

[Sandyn]

It's unlikely, but check for filter caps. There could be an X cap between live and neutral and Y caps between live/earth and neutral/earth. They are designed to fail in a safe way, so shouldn't be the problem, but Y cap/s if fitted can cause high earth leakage.

 

[guineafowl21]

Looking into this a bit further, it seems that washing machines perform a power-on self test, which involves activating the door lock, then checking various systems. This could be why the motor is causing the fault, even though it shouldn’t be activating.

It’s possible there was a leak which wetted the motor, in which case drying it out in an airing cupboard may fix it. But not if carbon tracking has occurred.

So, to be clear, is it tripping the RCD at the moment it’s switched on at the wall, or when you activate a cycle?

 

[Amateur]

With so many house fires I would shy away from even tackling a job like this.
If you do anything that causes a fire not only could it cause damage and endanger life it could also invalidate home insurance.
Maybe going down the route of pricing a local electrician that gives a certificate for work carried out, against the price of a new washer?
Logic 7kg washer at Currys £170.

I had a similar situation four weeks ago with planer thicknesser motor.
Took it out still connected. Opened up all the boxes so he could see the wires then waited for an electrician.

 

[guineafowl21]

With so many house fires I would shy away from even tackling a job like this.
If you do anything that causes a fire not only could it cause damage and endanger life it could also invalidate home insurance.
Maybe going down the route of pricing a local electrician that gives a certificate for work carried out, against the price of a new washer?
Logic 7kg washer at Currys £170.

I had a similar situation four weeks ago with planer thicknesser motor.
Took it out still connected. Opened up all the boxes so he could see the wires then waited for an electrician.

Undoubtedly the voice of reason, but:

1. Electricians issue certs for notifiable work and installation testing, not washing machine repair. They are not specifically trained in this.
2. As you say, the callout and labour price would make the job economically unviable.
3. Throwing away a new machine for want of a bit of diagnostics is environmentally unsound, and goes against my ‘right to repair’ principles.

If we can find a distinct fault and repair like-for-like, and the electrical system has been properly installed, there is minimal risk, in my view.

 

[Spectric]

Electricians issue certs for notifiable work and installation testing, not washing machine repair. They are not specifically trained in this.

They do a lot more than this, but agree they do not repair washing machines although we can perform basic test on a motor, we carry insulation testers and can verify why the machine is causing the supply to drop out. The issue here is that the machine was working Ok before being relocated, so was it stored somewhere damp for a period of time before relocation and considering it is as new (5 cycles) then I suspect that if it is not damp then it may still work OK in its original location at the MIL's which suggest an issue with the supply in the new location. Based on this there is a potential need for a sparky but to save time & cost then power it up from another property before making any decisions.