| 摘要 |
PURPOSE:To attain reduction of cost of the titled switch device and also to increase the contact lifetime by forming a switch circuit with a thyristor adverse parallel connector and a mechanical breaker and using no thyristor element for a single phase component to secure a low resistor. CONSTITUTION:A thyristor connector 25 of an R-phase is ignited at first at a zero point of the anode-cathode voltage of a U-phase thyristor. Thus a single phase AC current flows toward an S-phase from the R-phase. Then a thyristor adverse parallel connector 27 is ignited at a time point when the anode-cathode voltage of a W-phase thyristor is set at 0V. Thus a 3-phase AC current flows. Then a parallel breaker 28 is applied and a commutation loop is formed with conductors 25 and 27 or a low resistor 26 and a main pole of a breaker 28. Thus the U-phase and W-phase can use the forward voltage drops of elements 25 and 27 as the commutation current sources and the drop of potential of the resistor 26 serves as a commutation current source for a V-phase. Furthermore time constant is reduced together with reduction of the commutation time. Both connectors 25 and 27 are ignited in an open action mode with the breaker 28 opened. Then the connectors 25 and 27 are turned off.
|
