| 摘要 |
PURPOSE:To prevent the layer short of a winding produced when the taps are switched by turning off a semiconductor switch connected to a certain tap after a semiconductor switch connected to another tap is completely turned off. CONSTITUTION:When a tap switching instruction is given from a tap switch selecting circuit 33, an output signal b1 is set at L and the output of an AND circuit 48 is also set at L. Thus an adversely parallel thyristor 28 is turned off. When the voltage set between both terminals of the thyristor 28 is set at a high level after the thyristor 28 is turned off, a voltage detecting circuit 38 is delayed by a minute time owing to its delay characteristics and products an output signal of H. As a result, the output signals of H are produced from both AND circuits 49 and 50. Then the output of a gate pulse amplifier 69 is set at H and an adversely parallel thyristor 29 is turned on the complete a switching action of a transformer to a tap 26 from a tap 25.
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