Remanace Calculations

[bigmantony]

Our Aim: to measure remanace on a Current Transformer using basic circuit components. I know there are expensive scopes that can help but I would like to get a more hands on approach.

Does anyone have any thoughts and information on this subject? There are a lot of descriptions for remanance out there but nothing in depth to help measure the phenomenon.

 

[CarlPugh]

Put a DC current through the current transformer. (gradualy reduce the current to zero)

Charge a good quality, large capacitance film capacitor to some DC voltage.

Place a storage oscilloscope across the current transformer.

Discharge the capacitor through the current transformer.

The area of the first square wave will be indicative of the remanace. It will be polarity sensitive depending on direction of current when the current cransformer was polarized and the direction the capacitor was discharged through it.

If when the capacitor is discharged through the current transformer, you get a sine wave, use higher voltage or a larger capacitance capacitor. (A resonant frequency of 60 hertz should work)

Yes if the test is done correctly, you will get a series of damped square waves eventually turning to sine waves.

The winding on the current transformer can be used to bias the current transformer core and to discharge the capacitor.

Let me know the results of the tests.
carl@pughmagnetics.com