RCDs and "Inverter" washing machines

[Poptasticdave]

Anyone got any idea why [LG] washing machines with "Inverter technology" continually trip RCD's? LG insist that the fault is not theirs and that the machine I know of should be connected to a non-RCD supply to remedy the problem.

Given that most machines are in kitchens, ergo Special Locations this seems to suggest that LG want consumers to deliberately use trailing leads or ask a spark to break the law for them (or have old installations!).

Does this happen with other brands of machine with "Inverter technology"? I

The one I know of at present lights up the neon on the wall switch for about 10 seconds if you switch the wall switch OFF whilst the machone switch is ON ... not sure if this is related to the tripping, but I don't like it as it suggests to me that if someone pulls the plug and then accidentally touches the pins they could get a jolt.

 

[Darkwood]

Alot of product have capacitive smoothing inc' washing machines and if unplugged quick enough can give a nasty jolt off the pins, if i recall hair-dryers were a no1 culprit for this but if the manufacturers fit a neon or the like it will drain the capacitive power quite quickly but as your the theme of your post i would be inclined to measure the designed earth leakage from the washer and make sure it alone is tripping RCD and not just adding to an already high circuit leakage.

 

[Richard Burns]

The suggestion to supply a non RCD protected circuit to prevent the RCD tripping is not a very sensible response from LG!
However a kitchen is not a special location and if the washing machine is on a fused spur, not a socket and the cable is appropriately protected then an RCD would not be required.

With the increase in computing power of electrical appliances I should think that they are becoming more and more IT designed and the capacitive coupling to earth gets worse and worse, LG have presumable designed their machines to have an efficient filter for the equipment that is pushing up the "residual current".

 

[Darkwood]

I hope LG have tested their inverters against rcd blinding! an effect where the harmonic frequency's can render the rcd innoperable and blind to a fault condition :O

 

[Richard Burns]

continually trip RCD's? .

I hope LG have tested their inverters against rcd blinding! an effect where the harmonic frequency's can render the rcd innoperable and blind to a fault condition :O

Doesn't seem to be a problem, they have got that down pat!!:cheesy:

 

[snowhead]

Last post on this thread;

http://www.electriciansforums.net/e...ions/48778-new-washing-machine-trips-rcd.html

 

[Poptasticdave]

Thanks for thoughts and suggestions so far everyone.

The house it is in was fully rewired only a couple of months ago (it's the "Mrs-Dow-The_road" who I posted about earlier this year: http://www.electriciansforums.net/e...in-teasers-theyve-got-me-beat.html#post575189) and the likelihood of there being an "already high circuit leakage" (thanks for the thought Darkwood) seems very slim, although as the rewire was done by a good electrician who I recommended and is still under warranty I'm not going to start testing - I'll get Mrs. DTR to fetch back the spark concerned if we end up with no other options than testing out her workmanship.

I don't think there can be any other circuit leakage from other appliances because as far as I can see the only other appliances on the same circuit are the tumble dryer and the fridge, and the washer still trips when they are unplugged (apparently the first service engineer sent out tried to blame other appliances so the householder tried to run the washer with everything else unplugged in front of the engineer and it still tripped).
The washer is new - only bought in early August - so can't compare against pre-rewire but all other appliances in kitchen were in use before rewire and didn't and still don't trip RCD.
In the CU the only other circuit on the same RCD is the shower pump, so I guess I'll try getting Mrs DTR to run washer with shower pump off at the isolator, and ask if she's ever been trying to use shower whilst washer on, to try to eliminate that too.
Thanks also to darkwood for info about RCD binding - not one I've heard of before - sounds like a major design issue for some appliance manufacturers.
Also thanks snowhead for link to other thread - at least that gives me some confidence that this isn't just an isolated issue meaning that this one machine is faulty, though how Mrs DTR will go on about getting this fixed I don't know. Have to say I don't like LG and my first thought was that it was just poor quality machine with a fault, but maybe I'm being too harsh on LG there.
I'll keep you all informed!

 

[sparks1973]

ramp the RCD with the washer off....then ramp again with it on....check the difference......dont forget...a new appliance can be faulty straight out of the box....

 

[Darkwood]

Just to expand on my Harmonics issue... as well as causing blinding of the rcd the inverter can generate harmonics that cause nuisance tripping but a full Harmonics analysis while the motor is running would be required and probably not a meter you have at hand, i only bring this up because i fit drives to motors and im forced to take out the rcd protection if existing and fit SI units which give the same 30mA protection but ignore the Harmonic frequencies..... Ive got an errie feeling this isn't going to be the last time we see a thread like this.

 

[sparks1973]

Just to expand on my Harmonics issue... as well as causing blinding of the rcd the inverter can generate harmonics that cause nuisance tripping but a full Harmonics analysis while the motor is running would be required and probably not a meter you have at hand, i only bring this up because i fit drives to motors and im forced to take out the rcd protection if existing and fit SI units which give the same 30mA protection but ignore the Harmonic frequencies..... Ive got an errie feeling this isn't going to be the last time we see a thread like this.

so you`d need a power quality analyzer for this....

 

[Darkwood]

so you`d need a power quality analyzer for this....

Not only that but an understanding of the results as well as an understanding of what effect said results will or wont have on the RCD..... thats even past my experience so not a real viable option and assuming the circuit you are plugged into checks out and dosn't develope the fault under load conditions then it may be a case of rigging up a clean temp' circuit with same rcd thats tripping covering it then onto a seperate rcd to see if results are the same.... just a matter of elimination really but LG must have sold a boat load of these so it would have reared its head alot if the design of the washer and inverter control were the issue (unless it is faulty)

 

[sparks1973]

Not only that but an understanding of the results as well as an understanding of what effect said results will or wont have on the RCD..... thats even past my experience so not a real viable option and assuming the circuit you are plugged into checks out and dosn't develope the fault under load conditions then it may be a case of rigging up a clean temp' circuit with same rcd thats tripping covering it then onto a seperate rcd to see if results are the same.... just a matter of elimination really but LG must have sold a boat load of these so it would have reared its head alot if the design of the washer and inverter control were the issue (unless it is faulty)

well you`d think they (LG) would have conducted aggressive type testing on these before considering them fit for release onto the market.....not a good image for a company as well known as LG to be getting recalls on product.....
i`d say pat this offender first...might just be its faulty....

 

[Darkwood]

Also consider the PAT should be done on the sensitive equipment setting but id be supprised if it showed anything as the motor and possibly the inverter would be off line dependant how the 'power on' works (standard switched or electronic power on button)... it may be the case you are only testing up to a power board.

 

[sparks1973]

i suppose you could come from the other way with the MFT.....like test the motor seperately...that would of course entail some dismantling to gain access....probably a waste of time...then theres always LG saying `you tampered with it`...or something like that....

 

[Darkwood]

Id just do the tests of Elimination to take all other possibilities out of the equation and then let LG worry about its washing machine, if the installation can be proven to not be the cause or part of it then id be straight on the dog and bone to where-ever i bought the machine from.