| 摘要 |
PURPOSE:To prevent a motor from overheating without stopping the operation by controlling so that the effective value of an input current does not exceed the limiting value at accelerating and constant-speed operating time. CONSTITUTION:The present current is detected by a current transformer 4, and a current effective value calculator 8 calculates the effective current value. The present speed is detected on the basis of a signal from a position sensor 2. Whether it is accelerating is judged from the detected result; if the accelerating, the effective current value is compared with the effective current value limitation at the present speed, and if arriving at the limitation, the acceleration is temporarily stopped for the prescribed time. If in constant-speed operation, the effective current value is compared with the effective current limitation at present time, and if arriving at the limitation, the speed is decelerated by the prescribed amount. |
