Common Abnormalities of Current Transformers

When we use a current transformer, the three-phase voltage is only unbalanced, and when one phase decreases, the other two phases are very normal and the line voltage is very abnormal or accompanied by sound and light signals. In this case, it is very likely that it is mutual inductance. It is possible that the high-voltage or low-voltage fuse of the device has blown.

When we have a very effective grounding system at the neutral point and the three-phase voltage indicates that the unbalanced one phase drops but the other two phases rise or the pointer swings, then there may be a fault or fundamental frequency resonance when the single phase is grounded but If the three-phase voltage rises at the same time and exceeds the line voltage, it may be displayed due to frequency division or high frequency resonance.

If the high-voltage fuse is blown multiple times, it is likely that the part of the internal insulation of the equipment has been seriously damaged, such as a short circuit between winding layers or turns, and the other is a very effective neutral grounding system. When the busbar is switched off, the phase voltage rises and oscillates at a low frequency, which is generally a phenomenon of series resonance. When the phase voltage suddenly rises or falls abnormally, it is likely that the transformer is internally insulated. Damage, for example, is the fault of the insulating support and the short circuit between the winding layers or between the turns.

If the voltage transformer in the neutral point ranger's grounding system shows very unstable indication of the voltmeter when it is put into operation, it may be that the contact of the high-voltage winding end is poor when it is grounded. It is very easy to be personally threatened.