Was given a very tidy, looks almost unused, machine. Had broken fan belt which I replaced. Runs fine reversing etc on "airing". However once on heat runs for 10 or so minutes and then pops the RCD on the DB. The breaker remains live. Did notice the wall plug was warm to the touch.
Took the drum out. Very little dust and a couple dead cockroaches. No sign of any wiring damage etc, motor spins freely. Put it back together - still has problem. As it doesn't pop the breaker I presume it must only be a leakage problem rather than a short or overload.
As it's a reversing unit I wonder if perhaps the capacitator might be duff (its dated 05/1999)
Any suggestions you wise people?
tweake,
Mar 3, 8:36am
i'm picking stuffed element. sounds like element is leaking to earth when hot, which is something i've had before.
supernova2,
Mar 3, 9:27am
Could be I suppose. Any way of testing it? Check with previous owner. They chucked it because it kept tripping the thermal overload. Obviously would do that without the fan belt. Its been in the shed couple years so suppose the element might have got damp
ira78,
Mar 3, 7:46pm
Possibly repeated overheating fried some insulation or something. You might be able to see something if you can get a good look around the element, check the wiring.
msigg,
Mar 3, 7:55pm
Yes I had a grill that did same thing, insulation breaking down after a while when hot.
onl_148,
Mar 3, 9:47pm
It sounds like the RCD is doing exactly what it was installed to do. that is good ! A sparkie with an insulation tester should be able to determine if there is a earth / insulation problem. If you have a multimeter capable of measuring resistance / ohms, you could do a simple test which MAY show the element as the suspect. With the unit turned off and cold measure each leg of the element to earth. it should be super high / infinity. now run the unit until the RCD trips then immediately while the unit is still hot, do the same test. if the resistance has dropped a hell of a lot, then the element is breaking down to earth, such that the earth leakage current is high enough for the RCD to trip. greater than 30mA !
tweake,
Mar 4, 4:22am
difficult to test as the element needs to be hot when you test it. often it will act as no connection to ground when cold. i'm picking running it with no belt until it tripped the overload, has buggered the element or possibly other wiring. just check the wiring and see if there is anything melted. other than that i would not bother trying to fix it.
pamow69,
Mar 4, 8:06am
Definitely sounds like what Tweake said in post 2. Element will work at first then when hot, leaks to earth and trips earth leakage breaker. A dead short would trip the normal breaker. An insulation tester is what is needed and it will show if the element is leaking to earth. Not that expensive for a new element if you want to keep it. If you have a local service person and you take dryer to them and ask nicely, they may even put a tester on for you.
gph1961,
Mar 4, 8:11am
use a different thing eg 2000w heater to see if it pops rcd
supernova2,
Mar 4, 8:36am
The plot thickens. Had another good look at it. It truely looks almost brand new drum support pads and drum spigot bush are unmarked. No marks/scratches inside the drum. No signs of any wiring damage or hot spots. So turned it on and ran it for 4 hours continuously. On either hot or warm it will run happily for the full 160 minutes of the timer. On airing it will run for the full time (say 15 mins) on either side of the timer. HOWEVER if on either hot or warm it pops the RCD as the timer counts down across the gap between heat and airing.
Given that I think we can all rule out an element, capacitor, wiring or motor fault.
That only leaves the timer. Would it be possible that the timer has a earth leak when it switches the element out of the circuit to let it do the airing cycle. The timer is a ZBN 8359-01 B01 574 300 0180
As it turns out my dryer is the same model so could do a timer swap but rather than become a swapatron thought best to ask first.
gpg58,
Mar 4, 8:47am
Have you tried plugging it into another outlet, on a different RCD? wondering if its tripping early.
Not same as yours as i see yours works on hot ok - I Bought a cheap combo microwave that was doing the same on any setting using grill or convection elements, but fine on microwave. So i ran it on a non rcd circuit for an hour using each, which dried out the elements, and has never tripped original circuit since.(used to happen with old stoves etc as well, dry them out, and all's fine afterwards).
supernova2,
Mar 4, 9:51am
That's good thinking. I'll drag it into the laundry and try the outlet that mine uses. Mind you that might just prove that the laundry RCD is a dud.
Its weird as the controller/timer is the bit that reverses the motor as well and that's working. It appears it's just when it switches the element off. Poltergeist maybe?
ira78,
Mar 4, 7:19pm
It's possible the timer is fine, some RCDs are more sensitive and give more false trips than others. If it's a mechanical timer, they sometimes have a little spark when switching. It's not really a fault, but will trip some RCDs. I had my fish tank on an RCD that would randomly trip when the timer turned the lights on or off with two different mechanical timers. Replaced it with a digital timer, no problems. Except it would then trip every time there was the tiniest flicker in the power.
Soooo, Uhhh. Try it on another RCD now that you know how to reproduce it.
vivac,
Aug 14, 12:04am
If you have a non RCD outlet and a sensitive clamp meter you can isolate when the problem is happening. With some circuits there can be induced voltage in the earth cable, nuisance tripping can be an issue as an appliance will leak say 15mA but the induced voltage on the green wire can sit fairly high too, worse on long runs, and much worse on 10mA installations or circuits where multiple appliances are leaking a small amount.
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