| 摘要 |
<p>There are provided a transformer (TR) having a primary winding an end of which is connected to an input terminal of single-phase three-wire system (R1) and a secondary winding magnetically coupled to the primary winding and connected between the input terminal (R1) and an output terminal (R2); a voltage monitor circuit (VS) connected between the input terminal (R1) and an input terminal (N1) for monitoring an input AC voltage; and a switch (SW1) for selectively connecting the other end of the primary winding. The voltage monitor circuit (VS) causes, based on the monitored input AC voltage, the switch to be connected to the input terminal (R1), the input terminal (N1) or an input terminal (T1).</p> |
