0 Overview When the electricity meter is wired correctly, the measured electrical energy will be exactly equal to the energy consumed by the load or transmitted through the line. Conversely, if the wiring is incorrect, the measured electrical energy will not match the energy consumed by the load or transmitted through the line, and the degree of miscalculation varies depending on the wiring configuration. Therefore, ensuring correct wiring of the electricity meter, correctly analyzing the wiring configuration, and accurately deriving the mathematical expression for measuring electrical energy under various wiring configurations is crucial. As we know from basic electrical engineering knowledge, electrical energy is the product of power and time (this article only studies reactive energy), i.e., AQ = Qt, where AQ is the reactive energy consumed by the load (kvar·h); Q is the reactive power of the load (kvar); and t is the time the load uses electricity (h). From the above formula, we can conclude that to determine whether the electricity meter can accurately measure the energy consumed by the load, we need to examine whether the power measured by the electricity meter is equal to the actual power consumed by the load to judge whether the electricity meter wiring is correct. In other words, if the expression for the three-phase reactive power measured by the electricity meter under a certain wiring configuration conforms to the following form, the wiring is correct; otherwise, the wiring is incorrect. A few years ago, the Daxing power station, which was connected to our company's grid, discovered during electricity meter calculations that the active power meter was running in the forward direction, while the reactive power meter was running in the reverse direction, and the reactive power consumption was higher than the actual reactive power generated by the plant (calculated based on the reverse rotation). Upon investigation, it was found that the A and C phases of the reactive power meter's power supply sequence had been swapped. Based on this, the analysis is as follows: [b]1 Correct Wiring[/b] The reactive power meter in this station's metering device is a DX8 type two-element three-phase reactive power meter (60° phase angle difference three-phase reactive power meter). The voltage coil inside the meter has a resistor in series, causing the current in the voltage coil to lag the voltage by 60°. When the load is inductive, the correct wiring of this meter is shown in Figure 1. Its phasor diagram is shown in Figure 2. [img=350,593]http://zszl.cepee.com/cepee_kjlw_pic/files/wx/hndl-1/47-1.jpg[/img] Since the angle between the voltage and magnetic flux in an active energy meter is 90°, while the angle in this meter is 60°, it is equivalent to shifting the voltage forward by 30° compared to a regular active energy meter. The power calculation formulas for each component are as follows. Power measured by component 1: [img=340,188]http://zszl.cepee.com/cepee_kjlw_pic/files/wx/hndl-1/47-2.jpg[/img][img=320,288]http://zszl.cepee.com/cepee_kjlw_pic/files/wx/hndl-1/48-1.jpg[/img] It can be seen that, with the wiring as shown in Figure 1, the power P measured by component 2 is exactly equal to the reactive power of the perfectly symmetrical three-phase circuit. Multiplying this by time gives the reactive energy within the three-phase circuit. 2. Incorrect Wiring 2.1 In Figure 1, the power supplies of phase A and phase C are interchanged, while phase B remains unchanged. The current and voltage coils connected to the energy meter remain unchanged. The phasor diagram is shown in Figure 3. The power measured by the two elements of the energy meter are as follows: [img=350,559]http://zszl.cepee.com/cepee_kjlw_pic/files/wx/hndl-1/48-2.jpg[/img][img=280,50]http://zszl.cepee.com/cepee_kjlw_pic/files/wx/hndl-1/48-4.jpg[/img] It can be seen that this wiring causes the reactive energy meter to reverse, and the measured result is not the reactive energy in the three-phase circuit. 2.2 Interchange the power supply of phase A and phase B in Figure 1, keep phase C unchanged, and keep the current and voltage coils connected to the energy meter unchanged. Its phasor diagram is shown in Figure 4. The power measured by the two elements of the energy meter are as follows: [img=400,604]http://zszl.cepee.com/cepee_kjlw_pic/files/wx/hndl-1/48-3.jpg[/img] 2.3 By swapping the power supplies of phase B and phase C in Figure 1, while keeping phase A unchanged, and keeping the current and voltage coils connected to the energy meter unchanged, the measurement results are the same as in 2.1. 3 Conclusion From the above analysis, it can be seen that the wiring of the DX8 type reactive energy meter is closely related to the voltage phase sequence. Only by wiring according to Figure 1 can the reactive power in the three-phase circuit be accurately measured. Therefore, the metering device of this power station must verify the phase sequence of the three-phase voltage. Only by confirming that the voltage is in the positive phase sequence can the accuracy of the meter wiring and measurement be guaranteed.