An operation circuit is set to a conductive state in a case where a three-phase alternating-current power supply switching circuit receives an R phase and an N phase. An internal switch is set to a non-conductive state in a case where the state of the operation circuit is the conductive state. One contactor electrically connects an input terminal to output terminals in a case where the state of the operation circuit is the conductive state. Another contactor electrically disconnects input terminals from the output terminals in a case where the state of the internal switch is the non-conductive state.