| 摘要 |
<p>PURPOSE:To suppress abnormal phase voltage rise under unbalanced load by providing an unbalance voltage regulating section for lowering the output voltage from a detecting/smoothing section, when a three-phase load is balanced, and feeding the lowered voltage while feeding the output voltage from the detecting/smoothing section as it is, when the three-phase load is unbalanced, between the detecting/smoothing section and a detecting/comparing section. CONSTITUTION:When one phase output voltage is higher than 240V under unbalanced load, a Zener diode DZ3 is turned ON thus turning a transistor Tr7 ON. Consequently, a resistor R5 is shortcircuited and the voltage to be applied onto a Zener diode ZD1 in a detecting/comparing section 7 increases to lengthen the OFF time of transistors Tr1, Tr1' in a field current control section 8 thus reducing the field current flowing through a field coil 3. By such arrangement, output voltage of a main generating coil 2 drops from above 240V down to 220V.</p> |
