A practical on-site analysis method of smart electricity meter wiring with the reversed secondary polarity of voltage transformer

摘要

High-voltage three-phase three-wire energy meter is widely used in small current grounding system, whose neutral point ungrounded or grounded through arc suppression coil in 35kV and below voltage level. In particular, 10kV power customers mostly use this three-phase two-element electric energy meter to measure electric energy. Because the voltage transformer and current transformer are connected with the meter, the wiring is more complicated. After the meter have been installed, there may be some problems which will lead to incorrect measurement. Among these wrong wirings, the reverse polarity of the secondary side of the TV is difficult to distinguish. An initial judgment for TV secondary polarity reverse wiring can be obtained through conventional data measuring. Assuming that the uv (or wv) phase polarity is reversely connected, analyze the line voltages related to phase v, determine another line voltage vector in the vector diagram according to the angle between the two line voltage vectors on corresponding measuring elements, and identify current vector position through the phase angle from voltage vector. Then the accurate analysis and judgment of the three-phase and three-wire energy meter TV secondary polarity reverse wiring can be achieved.