An overview,

At present, the neutral point of power supply in China's distribution 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 the ground.

According to statistics, the fault of distribution network is largely caused by too much capacitance during single-phase grounding. Therefore, China's electric 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 the capacitance current, which requires the measurement of the capacitance current of the distribution network to make a decision.

In addition, the coordination between the ground capacitance of the distribution network and PT parameters will produce 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 necessary to accurately measure the ground capacitance of the distribution network.

The traditional methods of measuring the capacitance current of the distribution network include the direct method of single-phase metal grounding and the indirect measurement method of external capacitance, etc. All of these methods need to contact the primary equipment, so they have the disadvantages of dangerous test, complicated operation and low efficiency.

Automatic capacitive current tester, directly from the PT secondary side of the measurement of capacitance current in power distribution network, compared with the traditional test methods, the instrument need not dealing with a primary side, so there is no test, without waiting for lengthy scheduling command, just to meet the measurement line on PT open delta side can measure the capacitance current data.

Due to injection from PT open delta pilot test signals is weak, so it will not have any effect on the relay protection and PT, and avoid the work of 50 hz frequency interference signals, and the output end of the tester can tolerate 100 v ac voltage, when measuring system with single-phase grounding fault occurs, will not damage the PT and tester, Therefore, there is no need to do special measures, so that the work becomes simple, fast, and the test results are accurate, stable and reliable.

The tester adopts large screen LCD display, Chinese menu, operation is very simple, and small size, light weight, easy to carry outdoor operations, simple wiring, fast testing speed, high data accuracy, greatly reduce the labor intensity of the test personnel, improve the work efficiency.

Two, technical indicators

1. Measuring range and accuracy