| 摘要 |
PURPOSE:To realize an optimal protection corresponding to the load characteristics and to set an optimal protection characteristic curve easily by determining the load characteristics through an operating means while monitoring the load current and then realizing a protection characteristic curve from thus determined load characteristics based on a previously inputted set value. CONSTITUTION:Set values are previously inputted on ten keys 14 to a CPU 8 through a digital I/O unit 12 and stored in predetermined addresses in a RAM 11. The CPU 8 then reads in the load current of a motor 1 and determines a load current characteristic which is then employed for realizing a protection characteristic curve based on the previously inputted set values. When the load current exceeds the protection characteristic curve, load side fault is decided and displayed on a display 13 while furthermore a control signal is outputted to operate an auxiliary relay 15 so as to trip a circuit breaker 3. |
