| 摘要 |
PROBLEM TO BE SOLVED: To enable, if an instantaneous power interrupt or a power interrupt occurs in a power supply, prevention of free-running of a motor and decelerate and stop the motor within a fixed time, through inexpensive, simple constitution. SOLUTION: If an instantaneous power interrupt or a power interrupt occurs in an alternating current power supply 37, and an undervoltage signal UV is turned on, a constant time decelerating means 35 installed in a controlling means 23 opens contacts 29, 30 for invalidating an operation command ST and a speed command value FC from the external. A deceleration rate for stopping a motor in a certain constant deceleration time (t) (deceleration time (td): defined as the time required from the highest frequency FH to stop) is calculated from the output frequency (f) of an accelerating and decelerating means 31 at that time, using the following equation, and is set on the accelerating and decelerating means 31 td=FH/f×t. |
