| 摘要 |
PURPOSE:To obtain stable trip characteristic by tripping on the basis of a first digital voltage signal when a load current exceeds a set maximum voltage or on the basis of a second digital voltage signal when the load current is a set maximum value or less. CONSTITUTION:When an accident occurs, analog voltage signals Va-Vc corresponding to load currents Ia-Ic are input to signal selecting means 34 controlled by operation command signals Sa-Sc from a signal processor 38. An A/C converter 37 converts an analog voltage signal from a non-inverting amplifier 36 to a second digital voltage signal in a state that the analog voltage signal does not exceeds a set maximum value. It converts the analog voltage signal before it is amplified by the amplifier 36 to a first digital voltage signal in a state that it exceeds the set maximum value. The processor 38 detects the presence or absence of an accident current on the basis of the first and second signals, turns ON a thyristor 39 to conduct a tripping unit 40. |
