PURPOSE: To prevent electrical influence such as short-circuit and grounding at the control side of a central control room affected on a load side by performing the transmission of an operation signal between a central control room control board and a remote operation stopping control board outside central control room in optical multiplex transmission.

CONSTITUTION: When a state where an operator cannot approach the central control room occurs, the operator switches a mode change-over switch 5 arranged at the remote operation stopping control board 42 outside central control room to an (RSS) side. Thereby, the contacts 14, 19 and 21 of the mode change-over switch 5 are closed, and the contacts 15, 18 and 20 are opened. As a result, a green lamp 32 and a red lamp 33 for operation display are connected to a DC motor control center 3 similarly as the operating switch 31 of a DC pump motor 4 arranged on the control board 42. Instead of that, since the operation signal from the control board 41 at the central control room is separated, the motor 4 can be operated and controlled with the control board 42 hereafter similarly as in the operation of the control board 41. Since the contact of the switch 5 is opened, no influence of an error signal is applied on the control center 3 even when it is outputted due to a fault in a multiplex transmitter 43, etc.