| 摘要 |
PURPOSE:To continue the normal operation even if a control signal becomes abnormal by stopping a variation in the output of a variable frequency power source to maintain the present state if an input signal is out of a range of the prescribed change rate. CONSTITUTION:When a variable frequency power source system is normal, even if a control signal 8 is stepwise, functional input signal, an output signal from a controller 7 increases or decreases at the prescribed gradient. On the other hand, a change rate detector 3A for checking that the gradient of an output signal from the controller 7 falls within the prescribed range is provided at a variable frequency power source 3 side. Accordingly, when the change rate detector is not operated, the output of the controller 7 is always normally transmitted to the power source 3, and when the detector is operated, it is judged that a malfunction occurs due to a disconnection of a signal wire 9, a variation in the output of the power source 3 is interrupted by the output of the detector to maintain the present state. |
