| 摘要 |
PURPOSE:To control the number of revolution properly by forming the controller of the liquid resistor connected to the secondary side of the induction motor by a digital processor and A/D converting and inputting the primary current detecting value and current target value of the induction motor. CONSTITUTION:The liquid resistor (LRH) is connected to the secondary side of the induction motor. The LRH controller 50 is formed by the digital processor having a logical operation function as a computer. The detecting value of the primary currents of the induction motor and signals RH, RL, RU, RD indicating the states of a high-speed clutch 8, a low-speed clutch 7, a contactor 10 for lifting an electrode and a contactor 11 for dropping the electrode are inputted to the LRH controller 50, and the present states of the clutches 7, 8 and the contactors 10, 11 are decided. A state that the clutches and contactors must shift next is decided in response to the magnitude of difference between the detecting value of the primary currents of the induction motor and the target value, and only digital output, which must be varied, among digital output SH, SL, SU, SD is operated. |
