State grasping device and opening and closing control device for a power switching device using this state grasping device

It aims to optical adjustment to obtain a state grasping device capable unnecessary and and miniaturization. The excitation current waveform of an electromagnetic coil for opening the electromagnetic operating device for driving a movable contact of the power switching device has an inflection point P appearing in the next maximum value imax as current J in FIG. 5, the inflection the point is generated at the time of contact opening. Therefore, it is possible to determine the contact erosion quantity from time course of time tp. Therefore, both not shown, the position of the inflection point P by the inflection point search means, for example determined by paying attention to the rate of change of current (di / dt), the inflection point by contact erosion quantity calculation means and from time course of time occur tp to obtain the amount of wear switching contact. Can mechanical detecting means including optical detection means required, the apparatus can be so small inexpensive. Stroke ST of the movable iron core for driving which is connected to the movable contact is as shown in illustration, Act3 is opening completion point.