在中性点非直接接地电网中，单相接地及由电压互感器(PT)引起的谐振过电压均是多发性的事故。

In ungrounded distribution system the single-phase-grounding and the ferro-resonance caused by the PT (Potential Transformer) are of the frequent accidents.

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在中性点不接地电网中，频繁发生由电磁式电压互感器引起的铁磁谐振现象。

In the neutral ungrounded power system, ferroresonance over-voltage due to electromagnetic transformer takes place frequently.

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