三相异步电动机断相保护器

详述了断相保护器的电路结构与工作原理。当电容C2上的电压上升到BT33C的峰点电压时,小灵敏继电器KA通电,切断电动机的电源,从而避免了三相异步电动机单相运行致使电流过大而被烧毁。为了使小灵敏继电器KA通电充分,能确保其常闭触点断开,及时切断电动机的电源,应使BT33C的电流不会很快降到谷点电流以下,电容C2上的电压能较长时间的大于BT33C的谷点电压。由于电容C2上的电压不能跃变,这样可避免电网三相电压瞬间不平衡造成断相器误动作。

Three-phase Induction Motor Protector of Breaking Phase

This paper scrutinizes the working principles and electronic structure of three phase induction motor protector. When the voltage of capacitor C2 increases to the submit of BT33C, the litter sensitive relay KA is connected so as to cut off the electrical source of motor. So it will not be destroyed when current is too big. In order to charge the delay of KA fully, assure the break of closing point, and cut down the source of the motor, the BT33C should not drop to the bottom too quickly. The voltage of C2 should be kept higher than the bottom voltage of BT33C for a longer time. Because the voltage of C2 can not change swiftly, this will avoid the wrong operation when three phrase voltage is unbalanced.