Abstract: Abstract: The display value of an energy meter in a 10kV outgoing line interval metering circuit is abnormal. Due to the maintenance personnel colliding the outgoing wires of the secondary winding of the A-phase current transformer in the metering circuit during the wiring replacement process, the characteristic test of the current transformer was conducted separately before replacement, rather than conducting the characteristic test of the current transformer in the terminal box after connecting the secondary wires, The correctness of the secondary wiring has not been verified; Causing secondary circuit shunt, ultimately resulting in an imbalance between the A-phase current displayed on the energy meter and the B and C phase currents. This article, based on the principle of shunt circuit shunt, elaborates on the method of finding different shunt currents by changing the secondary load value of the metering circuit, verifies the existence of the shunt circuit, and proposes suggestions for improving the installation process and testing methods of current transformers.