| 摘要 |
PURPOSE:To prevent the overvoltage and the undervoltage produced at the secondary side by controlling a reactive power supply circuit via a limiter after detecting the secondary side voltage of a three winding transformer where the reactive power supply circuit is connected to the tertiary side. CONSTITUTION:The secondary side voltage of a three winding transformer is detected by a secondary side voltage detecting circuit 11 and compared with the 10% and 20% overvoltages by comparators 12-1 and 12-2 respectively. In an overvoltage mode the ON state is controlled for switches 14-1 and 14-2 of Zener diodes 17 and 18 forming a limiter. Then the gain of an operational amplifier 15 is reduced. Thus the output of a reactive power deciding circuit 9 obtained through the amplifier 15 which controls the reactive power supply circuit is limited. As a result, the reactive power is compensated in response to the secondary side voltage. So is with the shortage of the secondary side voltage. Thus no overvoltage nor undervoltage are produced at the secondary side. |
