Insulation monitoring system comprising multiple insulation monitoring devices, and a method for controlling insulation monitoring devices constituting same system

A method of controlling one of multiple insulation monitoring devices constituting an insulation monitoring system, the method comprising:

• switching a signal generation unit that applies a pulse signal to one of at least one internal line linked to a power line through a transformer to a deactivated state;
• maintaining the signal generation unit in a deactivated state until a preset notification signal is received from one of at least one other insulation monitoring device constituting the insulation monitoring system that are connected to one another while the signal generation unit is in a deactivated state;
• switching, when the notification signal is received, the signal generation unit to an activated state;
• calculating an insulation resistance between the one internal line and the ground according to the pulse signal applied to the one internal line from the activated signal generation unit;
• transmitting, when the insulation resistance is calculated, the notification signal to the at least one other insulation monitoring device that is communicably connected thereto;
• and
• repeating the steps of switching, when the notification signal is transmitted, the signal generation unit to a deactivated state, maintaining the signal generation unit in a deactivated state, activating the signal generation unit according to whether the notification signal is received, calculating the insulation resistance, and transmitting the notification signal.