| 摘要 |
PURPOSE:To enable to use a triac for controlling the primary voltage of a small current capacity by controlling a main circuit current at constant current with a main circuit current control circuit. CONSTITUTION:A main circuit current is detected by a current transformer 11, the output signal is converted via a signal converter 12 into the prescribed DC voltage signal, and fed back to a comparator 6 through a clipper 13. Thus, when the main circuit current flows more than the value set by the clipper 13, a signal is outputted from the clipper 13 and fed to the compararor 6. This signal is operated in the direction for reducing the primary voltage of a fan drive motor, thereby controlling the current value constantly. When the main current becomes small and lower than the set value of the clipper 13, the clipper 13 is turned OFF, and the circuit is operated only by the constant voltage. |
