AC SWITCH, UNINTERRUPTED POWER SUPPLY DEVICE EQUIPPED WITH SAME, AND INSTANTANEOUS VOLTAGE DROP COMPENSATOR

摘要

An AC switch (1) is provided with a first thyristor (T1), a second thyristor (T2), a third thyristor (T3), and a fourth thyristor (T4). The first thyristor (T1) has an anode connected to an AC power supply (2) and a cathode connected to a load (3). The second thyristor (T2) is connected in anti-parallel with the first thyristor (T1). The third thyristor (T3) has an anode connected to the AC power supply (2) and a cathode connected to the load (3). The fourth thyristor (T4) is connected in anti-parallel with the third thyristor (T3). A current detector (5) detects an AC current supplied from the AC power supply (2) to the load (3). A control device (6), in accordance with a detection value from the current detector (5) and in each period of the AC current, causes the first thyristor (T1) and the third thyristor (T3) to conduct alternately and causes the second thyristor (T2) and the fourth thyristor (T4) to conduct alternately.