| 摘要 |
PURPOSE:To simplify the controller of a lifting electromagnet by a method wherein whole thyristors of six pieces are triggered wholly at initially exciting time of a coil for the lifting electromagnet, and feeding of the gate signals of the thyristors of two pieces constructing one arm are stopped at ordinarily exciting time. CONSTITUTION:A control rectifier circuit 2 is formed by constructing thyristors 2a-2f in three-phase whole-wave bridge connection, a three-phase AC electric power source 1 is connected to the input side, and a coil 3 for lifting electromagnet is connected to the output side. A trigger circuit 4 feeds the whole trigger signals of the thyristors 2a-2f. When the coil 3 is to be initially excited, signals to trigger wholly the whole thyristors 2a-2f are fed from the circuit 4 by setting a control circuit 5. After the rise of the current of the coil 3 is completed, the circuit 4 is made to act according to the operation of the circuit 5 to excite the trigger of only the thyristors 2a, 2c, 2d and 2f. Moreover when the electric power source voltage drops, the circuit is changed automatically over three-phase whole-wave control to prevent a loading substance from an unexpected drop. Accordingly, the controller can be simplified. |
