current transformer detection

[DNA2683]

HI all,


I'm looking for a suggestion how to build a current transformer detection ( short) , i have a several current transformers ( with different resistant's ) that my board can support (i sample the current transformer @ 50HZ for voltage readings ). i want to design a circuit that works in parallels to my regular voltage reading circuit that detect a short in current transformer . any suggestion for a concept for this one?


TNX

 

[barry]

How about a small series resistor so you can measure the voltage across it. You don't give us a lot to go on.

 

[FvM]

A current transformer winding short would be regularly detected by a calibration check, deviation of primary to secondary current ratio from expected value. To check it from the secondary only, you can measure the output impedance by either injecting a current or switching the shunt resistance in operation.

 

[DNA2683]

A current transformer winding short would be regularly detected by a calibration check, deviation of primary to secondary current ratio from expected value. To check it from the secondary only, you can measure the output impedance by either injecting a current or switching the shunt resistance in operation.

Thanks FVM

i'm looking to find a short on the wires between my board to the current transformer ( not in the winding ) , can you suggest concept for this?
i sample the current transformer @ 50HZ for voltage readings so i need to have a solution that not interfere to the regular reading. BTW my board support several current transformer with different resistants.

 

[barry]

Detect a short from the wires to where? Ground? Each other? Power? My car's battery? You don't give us enough information.

 

[KlausST]

Hi,

Very unclear...
Do a simple (hand drawn) sketch about what you want to do.

Klaus

 

[FvM]

i sample the current transformer @ 50HZ for voltage readings so i need to have a solution that not interfere to the regular reading.

Most solutions will affect the regular measurement to some degree. As mentioned by others, you should specify the expected short circuit condition more clearly. If an earth fault is involved, an insulation monitor can detect it without interfering with the current measurement.

 

[KlausST]

Hi,

Maybe a tiny DC current through the current transformer ...

Klaus