Filter design for high power voltages Partial discharge detector
Perhaps using a ferite core can give you also a good result. As an example you have a resistor chain (or one long HV resistor) and capacitor that at 50Hz has big reactance, while at 50Khz acts like a short. Resitor limits the current, and the trasformer acts like a CT, main purpose is a galvanic isolation. Probably you have tried with some iron core xformer which can't transfer HF due to core loss.







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