Distribution network capacitor current tester

At present, the neutral point of the power supply in China's power system is generally not directly grounded, so the current flowing through the fault point when the line is single-phase grounded is actually the capacitance current generated by the line to ground capacitance. According to statistics, the faults in the power system are largely caused by excessive capacitance current during single-phase grounding of the line, resulting in arcing and the inability of the arc to extinguish on its own. Therefore, China's power regulations stipulate that when the capacitance current of 10kV and 35kV systems is greater than 30A and 10A respectively, arc suppression coils should be installed to compensate for the capacitance current, which requires measurement of the capacitance current to make a decision. In addition, the coordination between the ground capacitance of the power system and the parameters of PT can generate PT ferromagnetic resonance overvoltage. In order to verify whether PT resonance will occur in the distribution system and what kind of resonance will occur, it is also necessary to accurately measure the ground capacitance value of the power system.

Distribution network capacitor current testerThe traditional methods for measuring capacitance current include direct measurement with single-phase metal grounding and indirect measurement with external capacitance. These methods require contact with primary equipment, resulting in experimental hazards, complex operations, and low work efficiency. Subsequently, the method of injecting signals into the PT secondary side was introduced to measure the capacitance current of the power grid; Compared with traditional measurement methods, this method does not require the tester to be directly connected to the primary side during the measurement process, so there is no danger in the experiment. There is no need to do complicated safety work and wait for lengthy scheduling commands. Simply connect the measurement line to the open triangular terminal of the PT to measure the capacitance current data. The weak out of frequency test signal injected from the PT opening triangle will not have any impact on the relay protection and PT itself, while avoiding 50Hz power frequency interference signals.

On the basis of the previous generation of PT secondary injection signal method tester, our company has developed a new research and development designDistribution network capacitor current testceremonyAdopting a new hardware structure and faster ARM processor and AD converter, with a built-in new all digital variable frequency inverter power supply, it has high efficiency, low heat generation, small size, and light weight, making it easier to carry and test on site. At any time (including during the measurement process), the zero sequence 3U0 voltage can be accurately measured, making it easier for users to determine the system's operating status; And during the testing process, if the zero sequence 3UO voltage is too high, the measurement process can be automatically stopped.

Adopting industrial color LCD screen (readable under strong light), Chinese menu, more user-friendly human-computer interaction, and equipped with functions such as USB storage and data printing. The wiring is simple, the testing speed is fast, the testing stability and data accuracy are high, greatly reducing the labor intensity of the testing personnel and improving work efficiency.