[Technology Program] When installing the device for managing three-phase imbalance in distribution areas, how are phase-changing switches selected?

Installation of phase-changing switches should be determined based on the capacity of the distribution transformer and the characteristics of the distribution lines to effectively address three-phase imbalance issues in the distribution area. The significance lies in enhancing the overall economic efficiency of the power grid, reducing losses, conserving energy, extending the lifespan of transformers, preventing single-phase overloads to enhance transformer safety, and improving end-user voltage, thereby reducing customer complaints.

1.Principles for Selecting Areas for Management: To fully utilize the function of phase-changing switches and maximize the return on investment, the selection of areas for management should adhere to the following principles:

2.Determining the Number of Phase-Changing Switch Installations: The number of phase-changing switches should be determined based on the rated capacity and load curve of the distribution transformer. Based on extensive practical applications, the following table provides guidelines for the number of phase-changing switches. Users can flexibly adjust the number of phase-changing switches according to their management goals and desired effects.

Table for Configuration of Phase-Changing Switches in Distribution Areas:

3.Principles for Selecting Installation Points for Phase-Changing Switches

(1)The phase lines of the installation point for the phase-changing switch must be determined through topological identification to confirm the phase.

(2)The rated current of the phase-changing switch is 120A. It should control single-phase user loads ranging from 10A to 70A, and the monthly electricity consumption of the user's meter should be between 1800 kWh and 2500 kWh for better control effectiveness.

(3)Avoid selecting user meters with too low electricity consumption for control. Generally, meters with monthly total electricity consumption below 50 kWh should not be controlled to avoid weak regulation capability.

(4)Avoid selecting user meters with excessively high electricity consumption for control. It is recommended not to control meters with monthly total electricity consumption above 4500 kWh to prevent the phase-changing switch from tripping due to overcurrent protection.

(5)Preferably choose installation points for the phase-changing switch close to the T-junction of the three-phase four-wire cable to reduce cable length and engineering quantity.

(6)Avoid selecting installation points for the phase-changing switch directly above or in front of the user's door to avoid disputes.

(7)Prohibit selecting installation points for the phase-changing switch for three-phase meter users, strictly prohibiting control of three-phase loads.

(8)If the small branch line is a single-phase line and the total user electricity consumption on this branch line does not exceed the rated current of the phase-changing switch, the switch can be installed at the T-junction.

(9)After determining the number of phase-changing switches for each branch and phase in the distribution area, configure them according to the principle of first midsection, then end, and finally the beginning. Then accurately select points based on monthly electricity consumption data.

(10)Phase-changing switches can be evenly installed on each phase, or the installation quantity can be increased appropriately in the overloaded phase according to the load curve of the distribution area.