摘要 |
A control circuit for an a-c control element consisting of controlled rectifier elements in conjunction with a transformer in which a separate current transformer is provided for each of the transformer windings and all current transformers of the same respective phase have their secondaries connected together in a bucking circuit, to which a measuring arrangement is connected which measures the peak value of the difference value formed during each half-wave, and the output signal of which is introduced, depending on the polarity of the difference value, into the control circuit of the one or the other branch of the a-c control element. |