保定奥兰电气科技有限责任公司

1）相位说--间隙性弧光接地过电压的产生，是发生单相接地时相角超前电压90%的大的电容电流所致。在接地电容电流过零熄弧时，适逢电压的峰值，再由于电流较大，周围空气环境游离，耐压强度降低，而极易发生重燃，导致了暂态和稳态过电压的发生。在电网中性点接入电阻后，给接地点加注入了阻性电流。接地点流过的阻容性电流和电压之间的相位角会小于90°。若阻性电流与容性电流相等时，相位角为45°；若阻性电流大于容性电流，则相位角变得更小。这时，接地电流过零时，故障点的电压已经下降很多，降低了重燃的或燃率。

1) phase theory the gap arc grounding overvoltage is caused by the large capacitive current caused by the phase angle leading voltage 90% when the single-phase grounding occurs. The grounding capacitance current zero arc voltage, coincides with the peak, due to the current large, free air, the compressive strength decreased, and prone to occur again, the steady state and transient overvoltage. When the resistance is added to the neutral point of the grid, the resistance current is injected into the grounding point. The phase angle between the capacitive resistance current and the voltage passing through the site will be less than 90 degrees. If the resistance current is equal to the capacitive current, the phase angle is 45 degrees; if the resistance current is greater than the capacitive current, the phase angle becomes smaller. At this time, when the earth current is zero, the voltage at the fault point has dropped a lot, reducing the rate of re burning or burning.

2）泄漏说--在不接地系统中，发生单相接地时产生的过电压皆是在电容上聚集的能量无从泄漏所致。电弧的点燃、熄灭、重燃的过程，使中性点不接地电网中积累了多余的能量，加剧了重燃时的电磁振荡，增大了弧光接地过电压。在电网中性点接入适量的电阻，是把积累的能量，在电弧熄灭至重燃前（半个工频周期内），泄入大地。过电压就可以降低。电阻越小，释放的越快。

2) leakage theory - in ungrounded systems, the overvoltage generated by single-phase grounding is caused by the accumulation of energy on the capacitor without leakage. The process of ignition, extinction and re combustion of the arc makes excess energy accumulated in the neutral ungrounded grid, which aggravates the electromagnetic oscillation during re combustion, and increases the arc grounding overvoltage. In the neutral point of the network to access the appropriate resistance, the accumulation of energy, before the arc extinguished to re - combustion (half power cycle), discharged into the earth. Overvoltages can be lowered. The smaller the resistance, the faster it will release.