Field inspection technology of iron core ground-ing current monitoring device based on "vacuation after emptying"

In this paper, a new method based on "inject after emptying the current" is proposed for the field inspection of the core current monitoring device. First test the core grounding current characteristics ，and offset the current by the use of real-time tracking technology, and then, the standard current was injected for verification. The injected current is similar to that of the actual iron core, which is a mixed current with adjustable amplitude. The feasibility and effectiveness of the method are verified by the field test of the on-line monitoring device of the core of a 500kV transformer substation.