CHANGE-OVER METHOD OF MONITORING CONTROLLER

PROBLEM TO BE SOLVED: To provide a change-over method of a monitoring controller for monitoring a state of equipment or controlling the equipment, without causing a blackout in a power system.SOLUTION: A switch device 25 includes a first terminal 30 for connecting a first monitoring controller 20, a second terminal 32 for connecting a second monitoring controller 21, and a third terminal 33 for connecting equipment 15. A change-over method switches from a state in which the first monitoring controller is connected to the first terminal, the equipment is connected to the third terminal, and the second monitoring controller is not connected to the second terminal, with the first terminal being shorted with the third terminal, to a state in which the second monitoring controller is connected to the equipment, by performing a first step for opening between the second terminal and the third terminal, a second step for connecting the second monitoring controller to the second terminal, a third step for opening between the first terminal and the third terminal, and a fourth step for shorting the second terminal and the third terminal.