AUTOMATIC ADAPTATION INSULATION MONITORING RELAY FOR LEAKAGE CAPACITORING.

Abstract

The invention relates to an insulation monitoring relay and measurement method that automatically adapts to leakage capacitance for measuring insulation resistance in IT (isolated earthing network system) systems where the neutral line is not grounded. Within the scope of the invention, the leakage capacitance in the system is filled by applying a unidirectional DC voltage to the system via a measurement and DC voltage injection circuit (1), the time for this filling is detected via a sensing and control circuit (2), and the measurement time to be used in insulation resistance measurement is automatically determined based on this time. The insulation resistance measurement circuit (3) then performs the insulation resistance measurement of the system according to the determined measurement time. In this way, the relay automatically adapts to the leakage capacitance of the system, eliminating the need for the user to manually determine the leakage capacitance value or capacitance level, and provides more accurate and stable insulation resistance measurement.Furthermore, the invention can operate without being affected by the insulation resistance checks performed by inverters in IT (isolated earthing network system) systems before commissioning, and by the DC leakage effects that occur during this process.