PURPOSE: To grasp accurately a fault state even if a multiplex fault bridged over plural electric stations takes place by making the internal time of plural transmitters of stations to be controlled coincident with the time of a master clock of a control station.

CONSTITUTION: The internal time of an information transmitter TCR7 of a station to be controlled is made coincident with the time of the master clock 2 and if a fault takes place in a power system (not shown), its state change information is outputted to a display device CRT3 and an output typewriter TW4 with the state change time of hr/min/sec/10msec. Thus, even if a multiplex fault bridged over plural electric stations takes place, a lot of the state change information is transmitted from the device TCR7 to the control station and outputted to the device TCR3 and the typewriter TW4 with the state change time. Furthermore, the time setting of the clock in the device TCR7 is performed from the control station at initializing of the device TCR7.