In ungrounded distribution system the single-phase-grounding and the ferro-resonance caused by the PT (Potential Transformer) are of the frequent accidents.
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。
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The core structure of the arc suppression coil is improved to solve the nonlinearity of voltage with zero-excitation. The harm of ferro-resonance is thus reduced.
With examples this paper analyses the phenomenon of ferro-resonance caused by the grading capacitor and the effect of busbar's stray capacitance on ferroresonance.