Static switch

A static switch for switching between electrical connection and disconnection between an alternating-current power supply and a load, the static switch comprising:

• a thyristor switch connected between the alternating-current power supply and the load and including a pair of arms connected in anti-parallel, each of the arms including a plurality of thyristors connected in series;
• and
• a controller configured to perform on-off control of the thyristor switch,
• the thyristor switch being configured to be turned on in response to a gate signal supplied from the controller, and turned off in response to a current coming to zero in a state in which the gate signal is interrupted,
• the controller including:
• a phase detecting unit configured to detect a phase of a power supply voltage supplied from the alternating-current power supply, and
• a gate signal generating unit configured to interrupt the gate signal when an open command is provided to the static switch and when the phase of the power supply voltage detected by the phase detecting unit matches a target phase,
• the target phase being set outside of a phase range where interruption of the gate signal is prohibited, the phase range being set so as to include a zero crossing point at which a load current is switched in polarity.