Lincat ESLR9 electric cooker went bang

[jgaircraft]

Hi,

To give a bit of background, it is a Lincat ESLR9 electric cooker. It is very simple design with two fans and two elements.

Two weeks ago the cooker made a bang and tripped the consumer unit, upon inspection I could see that the contactor appeared burnt-out and a wire on a heating element was loose and burnt also, with signs of arcing on the connector. The contactor fitted was a IMO MB09-F-00.

I replaced the contactor with this unit from Ebay:

Lincat CO215 Contactor 230v 50/60 Hz for sale online | eBay UK

Find many great new & used options and get the best deals for Lincat CO215 Contactor 230v 50/60 Hz at the best online prices at eBay UK! Free delivery for many products!

www.ebay.co.uk

and replaced the heating element and replaced the female spade end connector.

Unfortunately the replacement contactor has burnt-out also, even though it is the part number stated in the manual and the oven is listed in the advert, perhaps it isn't the correct part?

My theory is the poor connection method of the replacement contactor? The original (IMO unit) had sturdy spade end connectors for good contact, the replacement, feeble little spring type terminals where the wire is shoved in and held loosely by a weak clamp (felt loose and could pull the wire out easily).

I'm thinking this might be causing high resistance/heat and hence overcurrent, but I'm not an electrical engineer and I might be overlooking something else. What to you think?

Regards

James

 

[davesparks]

If the connections are burnt then they were loose.

Are you sure you have made the connections to the contactor correctly? Siemens are a reputable brand and their terminals are not normally a problem.

The wires shouldn't just be 'shoved in' to those terminals, you open the spring clamp using a tool in the adjacent slot before inserting the wire into the terminal.

 

[Avo Mk8]

In support of davesparks comments above, preparation of the cable is also important - if the connecting wires to the original contactor (with spade connectors) got hot or 'burned' then the copper wire could have become annealed and/or oxidised. It would be important to cut back the wires to pristine shiny copper for the push-in type connectors to make good contact.

update - I note another outlet is saying the original spade connected IMO contactors are superseded with a version with terminals, and they claim this is suitable for the ESLR9

 

[jgaircraft]

Thank you both Dave and Avo, food for thought. I did insert a small screwdriver (not the Siemens own tool) into the correct aperture and then articulated the screwdriver to open the clamp enough to insert the wire. The wires went in cleanly and I then released/removed the screwdriver to clamp (but it wasn't very positive and left loose). I will investigate the condition of the wires and replace where necessary, this is something that never occurred to me. The contactor you post above Avo, with terminals, is worthy of investigation - thank you both very much!

Regards James.

 

[Avo Mk8]

The contactor you post above Avo, with terminals, is worthy of investigation

it was another eBay offering I'm afraid

REPLACEMENT FOR CO111 LINCAT CONTACTOR RELAY CO 111 FRYER OVEN WATER BOILER ETC | eBay

Find many great new & used options and get the best deals for REPLACEMENT FOR CO111 LINCAT CONTACTOR RELAY CO 111 FRYER OVEN WATER BOILER ETC at the best online prices at eBay! Free delivery for many products.

www.ebay.co.uk

 

[jgaircraft]

Thanks all the same for the link. Please excuse my ignorance, but why when the maximum power usage of the cooker is a combined 16.5kw, would a contactor rated at 4kw be big enough to cope? Sorry, I am sure this is a stupid question!

 

[Avo Mk8]

Thanks all the same for the link. Please excuse my ignorance, but why when the maximum power usage of the cooker is a combined 16.5kw, would a contactor rated at 4kw be big enough to cope? Sorry, I am sure this is a stupid question!

There are a pair of auxiliary contacts as well as the set of three phase contacts. As I read the list of performance criteria, the 4kW rating applies to the auxiliary contacts, not the three phases which are shown higher up the list at 22A ea. resistive load.
Mind you three 230V phases at 22A is about 15kW, not 16.5! So maybe this is a bit under-rated anyway - or perhaps there are other loads in the oven that make up the difference!

 

[jgaircraft]

Thanks Avo! I notice on the datasheet for this contactor that they do different coil voltage types. I am a bit confused by these, the 230V one, I assume is for a single phase installation? Mine is three phase, so would I need the -400, the 380-400V 50hz version?

 

[jgaircraft]

Sorry, I think only one phase is being used to trigger the coil i.e. the 230v at 50hz one is the fella.

 

[Avo Mk8]

Sorry, I think only one phase is being used to trigger the coil i.e. the 230v at 50hz one is the fella.

I think you are right. This should be confirmed by checking the coil voltage of the original (burnt) one!