ELCB,s.How do they work?

[La Poste]

I know they are a bit old now but they are still used a lot in countries like Thailand.

As far as I understand it an ELCB would be used on a TT system or where there is a high impedance earth loop.
A remote rod is put down into the ground say outside the property and this is then connected to the properties MET/ earthing/CPC system.

During an earth fault the fault current will try to make its way through the property CPC and then to the rod, the fault current will then try to find its way
through the ground and back to the star point of the transformer.

Because the resistance of the rod is quite large a voltage or volt drop will develop between the metalwork in the house and the rod and when this voltage
rises above say 50 Volts the ELCB will switch off the supply.

Inside the ELCB is a sensing coil that measures the difference in voltage between the metalwork inside the house and the ground rod outside.

Is this correct, is this the best way of looking at it?

Any comments appreciated.

Thanks.

 

[La Poste]

I'm guessing inside the ELCB is a coil, a coil that has a certain resistance and when a current flows through that coil a volt drop will appear across it, the more current that flows through the coil the higher the volt drop will be between both ends of the coil.

When the volt drop between both ends of the coil becomes 50 Volts or greater the ELCB will switch off the supply.

Is that correct?

 

[Des 56]

In the past I used to install them :death:


It's amusing to look back at what was the "in" thing to install,to find these days, they are now, rightly, only fit for the bin
Here is some info I found,it explains what I never knew and still don't :biggrin:


Working Principle of Earth Leakage Circuit Breaker (ELCB) and Residual Current Device (RCD) | EEP