Talking about the Characteristics of Single Phase Earth Fault

The short circuit of the power grid mainly includes four kinds. The most serious one is the three-phase short circuit, and the single-phase ground short circuit is the most common short circuit fault. In the actual operation of a 10kV distribution line, a single-phase ground fault often occurs, especially in In severe weather conditions such as rainy seasons, strong winds and snow, single-phase earth faults occur more frequently. For example, in Longsha Power Supply Bureau of Heilongjiang Province, of the 24 anomalies in 2005, single-phase ground faults accounted for 7 times. Of the 31 anomalies in 2006, single-phase ground faults accounted for 8 times. After a single-phase grounding occurs, the voltage of the fault ground decreases, and the phase voltage of the non-faulted two phases increases. However, the line voltage is still symmetrical, and thus does not affect the continuous power supply to the user. The system can operate for 1 to 2 hours, which is also a small current grounding. The biggest advantage of the system; however, if a long-term operation of the grid occurs after a single-phase earth fault occurs, it will seriously affect the safe and economic operation of the substation equipment and the distribution network.

Therefore, there must be no buildings, trees, etc. in a certain area around the wires, leaving “transmission corridors”. Overall, these are caused by load imbalances. Specifically, the most common causes of single-phase earth fault wire short-circuits are wire breakage, insulator breakdown, and shorting of trees.

GROUND FAULT characterized <br> <br> center signal: alarm bell, "a certain kV bus ground" bright light plate, arc suppression coil neutral point grounding system, as well as "arc suppression coil operation "The light card is bright;

Insulation monitoring voltmeter indicates: the fault phase voltage is reduced (not fully grounded) or zero (completely grounded), the other two phases are increased in voltage, are greater than the phase voltage (not fully grounded) or equal to the line voltage (completely grounded), and are grounded When the voltage meter pointer is not oscillating, if the voltmeter swings continuously, it is intermittently grounded;

Neutral arc suppression coil grounding system, with a neutral point displacement voltmeter, you can see a certain indication (not fully grounded) or indicated as the phase voltage value (completely grounded) arc suppression coil grounding alarm light;

When the arc is grounded, an overvoltage is generated, the voltage of the non-faulty phase is high, and the high-voltage fuse of the voltage transformer may be blown, and the voltage transformer may even be burned out.

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