SWITCHGEAR TO DETECT MALFUNCTION OF CURRENT TRANSFORMER BY SECOND CURRENT VARIATION IN LIVE WIRE STATE

摘要

The present invention provides a switchgear to detect a malfunction of a current transformer by second current variation in a live-wire state. According to the present invention, the switchgear comprises: a current transformer; a watt-hour meter or protective relay connected to a secondary line of the current transformer; and a current transformer internal malfunction detection apparatus connected to the secondary line between the current transformer and the watt-hour meter or the protective relay in series and detecting whether an internal malfunction occurs in the current transformer in the live-wire state by using variation between secondary currents which are measured when a test load is not inputted to the secondary line and when the test load is inputted to the secondary line, respectively. The internal malfunction detection apparatus comprises: a load input unit inputting the test load to the secondary line of the current transformer; a current measurement unit measuring the secondary currents when the test load is not inputted to the secondary line and when the test load is inputted to the secondary line, respectively; a signal processing unit processing a signal detected in the current measurement unit; and a control and calculation unit applying or removing a test load input signal to the load input unit, receiving the signal processed in the signal processing unit, and calculating a secondary current variation before and after a test load input to determine whether the malfunction occurs in the current transformer. Accordingly, the test load is inputted to the secondary line of the current transformer in the live-wire state and the levels of the secondary current changed before and after the test load input are compared, thereby detecting whether the malfunction occurs in the current transformer.;COPYRIGHT KIPO 2020