Failure detection of a semiconductor switch using first and second current detectors

A power supply system comprising:

• a semiconductor switch having a first terminal that receives AC power from a first AC power supply, and a second terminal connected to a load;
• a first current detector and a second current detector each of which detects an instantaneous value of a current flowing through the semiconductor switch, and outputs a signal indicating a detection value,
• the semiconductor switch including a first semiconductor element through which a current having a first polarity flows, and a second semiconductor element through which a current having a second polarity flows,
• the first current detector including a transformer that outputs an electrical signal having a value corresponding to a current detected by the first current detector,
• the second current detector including a magnetoelectric transducer that converts a magnetic field into an electrical signal, the magnetic field being generated by a current detected by the second current detector;
• and
• a failure detector that, when the detection values from the first and second current detectors are not equal, outputs a failure detection signal indicating that a current is not flowing through any one of the first and second semiconductor elements.