Patent ID: 6496012
Filing Date: 2002-12-17
Classification: H02H,H05B

Abstract:
An apparatus for detecting a short in a load which receives power from a transformer having a primary winding and a second winding, the load being connected to the secondary winding, said apparatus comprising:a waveform conversion circuit for converting a voltage signal and a current signal that represent a voltage signal and a current signal, respectively, of the primary winding into generally squarewave voltage and current signals, respectively, having a first DC offset voltage and a second DC offset voltage, respectively; a phase detector circuit for outputting a control signal having a first state when the generally squarewave voltage and current signals are substantially in phase and a second state when there is a difference in phase between the generally squarewave voltage and current signals that is greater than a predetermined phase difference; and a filter for filtering the control signal outputted by said phase detector circuit.