# Cramer EK2000 thermocouples, how do they work



## gm6vxb (Nov 3, 2007)

Had one of the rings on the cooker fail to stay lit.
Looking at the thermocouple I cannot figure out how it works.
There are two wires ? coming off the 'hot' end, one insulated and one not.
Both have Lucas' type connectors to the gas on/off regulator.
Before I strip the cooker does anyone know how they work and can they be tested off the cooker, or do I need gas flow as well.
Martin.


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## pippin (Nov 15, 2007)

When hot they produce a very low voltage between the terminals. This is used to operate the safety gas solenoid.

You could disconnect the wires and use a voltmeter on, say, 10V range to see if there is any output when you put the thermocouple into a flame.

Comparison with one of the others tested in the same way would establish whether the thermocouple is the fault.


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## hilldweller (Mar 8, 2008)

gm6vxb said:


> Looking at the thermocouple I cannot figure out how it works.


Am I miss-reading this ?
A radio ham who does not know thermocouples ?

OK, two dissimilar metals, joined, then heated generate a small voltage.

In the gas tap this is wired to a coil that keeps the gas passage open. You hold the flame on manually until the thermocouple is hot enough to generate enough current to hold the gas on.

Flame out and the gas is cut off.

So you can put a voltmeter or ammeter across the thermocouples and compare voltages.


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## gm6vxb (Nov 3, 2007)

A radio amateur knows about radio, thermocouples are for electricians.
Even in commercial radio I rarely come across a thermocouple, most having now been superceded by solid state devces.

Yes understand the principle, same as a Peltier device which is a semiconductor version of an electricians disimilar metal device, and I have used these to great effect to cool and heat devices which is more than a thermocouple will do.

Just needed to know what sort of voltage and current I would be looking for while hanging upside down under the cooker in a fairly confined space.
Having had chance now to take out the cooker this afternoon and investigate further the problem was just a poor connection on the earth side.


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