Logik cooker LDOC60W and its clones.

[BQW]

Need a answer to this one please.
I maintain about 25 of this Currys cooker model or its clones, and often have to replace the Elements because they have gone O/C, but on the odd occasion, after replacing the Element, and the oven is selected they just violently trip the MCB protecting the cookers supply.
And no matter how much fault finding I do, even using my Megger or meter, I cant find any obvious short circuit or leakage to earth.
Every thing reads ok ?
I have had it a few times now, so it must be a common fault, but what is it ?

 

[RandomGrinch]

Hi,

I may be very wrong, but how are the elements stored before you replace them?
If say, they are stored in a cold van, and then brought indoors, there could be some condensation formed on the element.
The insulation in the element is hygroscopic and sensitive to moisture.
This could possibly cause the trips?
After some warming up time and a couple of uses, the element shouldn't cause any further issues

 

[BQW]

Thanks for the reply, yes I am familiar about the ingress of moisture into Elements, but the resultant earth leakage, usually just trips the RCD or RCBO.
When I have encountered this particular problem, it really goes " bang", on one occasion it even took out one of the 3 phase incommers !
I naturally decided at that point, it was not worth the agro.
I have a suspicion, it might be the Regulator/stat for the oven braking down under load, but that's just a guess.
As I stated, all checks with a Meter and Megger even on the 1000v range, reville nothing !
The strange thing is, I have only ever encountered this problem with the Currys Logik clone of the cooker

 

[RandomGrinch]

after replacing the Element, and the oven is selected

Have you tried selecting the oven first and then turning it on from the isolator (after checking resistance is ok)?
If the MCB holds then, it would suggest the regulator may be the issue when switching.
Does the issue happen more on well used ovens?

 

[Harry Bloomfield]

Thanks for the reply, yes I am familiar about the ingress of moisture into Elements, but the resultant earth leakage, usually just trips the RCD or RCBO.
When I have encountered this particular problem, it really goes " bang", on one occasion it even took out one of the 3 phase incommers !
I naturally decided at that point, it was not worth the agro.

Moisture ingress will cause the RCD to trip, long before it would get to the point of drawing enough current to trip an MCB.

If the fault is enough to take out an incomer, then there will certainly be evidence of that in the oven, as in burned and blackened. Such a fault current would leave obvious evidence, it would not usually clear itself and resume normal operation.

 

[BQW]

Moisture ingress will cause the RCD to trip, long before it would get to the point of drawing enough current to trip an MCB.

If the fault is enough to take out an incomer, then there will certainly be evidence of that in the oven, as in burned and blackened. Such a fault current would leave obvious evidence, it would not usually clear itself and resume normal operation.

That thought crossed my mind at the time as well, but I could see no scorch marks, but then again their all thick with grease and carbon.
Only once did one trip the incomer, and that was after MCB feeding it had been reset about 4 times in succession.
As to there age, they average 4 years at most. but do get a very hard life.
Its a weird one aint it.
I did think of trying the old GLS Lamp in series trick, and see if that offers up any clues.