| 摘要 |
PURPOSE:To detect a voltage across a load without any transformer, by forming a closed circuit wherein the serial circuit of a switching element and a resistance for voltage detection is connected to the load in parallel through a full-wave rectifier in every cycle of an AC power source. CONSTITUTION:A reverse blocking three-terminal thyristor 49 turns on in synchronizing with a bilateral thyristor 2, so the closed circuit wherein the series circuit of a diode 46, resistance 48, reverse blocking three-terminal thyristor 49, voltage detecting resistance 50, and diode D3 is connected to the AC power source 1 and the closed circuit wherein the series circuit of a diode 47, resistance 48, thyristor 49, resistance 50, and diode D1 is connected to the load 3 are formed alternately in every half cycle of the AC power source 1. In one half cycle, a voltage corresponding to the voltage of the AC power source 1 is generated at the voltage detecting resistance 50 and equal substantially to the voltage across the load 3. In the other half cycle, a voltage corresponding to the terminal voltage across the load 3 is generated at the voltage detecting resistance 50. |
