随着电力系统网络规模的不断扩大和电压等级的不断提高，对故障选相装置的要求也不断提高。
Along with the continuous development of power system network and the continuous enhancement of voltage grade, the request is enhanced correspondingly to the fault phase selector.
随着电力设备电压等级的提高，人们对电力设备运行可靠性提出了更加苛刻的要求。
As increasing voltage grade of power electrical equipment, it is much more rigorous for the reliability of these equipment.
城市配电网因为其电压等级较低，为了提高系统供电的可靠性，曾广泛采用中性点不接地系统方式。
In distributions, because of its low-level voltage, its neutral point used to disconnect to the ground in order to improve its reliability.
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