How to deal with the open circuit fault of the secondary circuit of the current transformer?

1. Disable related protection: Once the secondary circuit of the current transformer is found to be open, the relevant relay protection device should be disabled immediately according to the regulations to prevent the protection from malfunctioning. Because in the open circuit state, the secondary side may generate a very high voltage, affecting the normal operation of the protection device.
2. Determine the faulty current transformer: Determine the faulty current transformer by observing and analyzing the abnormal indication of the circuit instrument (such as the ammeter indicates zero, the power meter indicates a decrease, the meter speed is slow or does not turn, etc.), whether the current transformer body has noise or uneven vibration, whether there is discharge and sparking at the secondary circuit terminals and component wires, whether the relay protection has malfunctioned or refused to operate, whether the watt-hour meter and relay are smoking and burnt.
3. Reduce the primary load current: If conditions permit, try to reduce the primary load current. If the current transformer is seriously damaged, the load should be transferred and the power should be turned off for inspection and treatment. For example, for some equipment that can switch loads, the load can be switched to other normally operating circuits or equipment.
4. Perform secondary short-circuit operation: Try to short-circuit the current transformer secondary with a good short-circuit wire as soon as possible on the nearest test terminal according to the drawing. When short-circuiting, a special short-circuit short-circuit wire should be used. The short-circuit should be properly and reliably, and it is forbidden to use fuses or general wire winding. It is necessary to operate according to the drawing to ensure that the short-circuit is correct.
5. Pay attention to the phenomenon during short-circuiting: If there is a spark during short-circuiting, it means that the short-circuit is effective, and the fault point is in the circuit below the short-circuit point, which can be further searched; if there is no spark during short-circuiting, it may be that the short-circuit is invalid, and the fault point may be in the circuit before the short-circuit point. The short-circuit point can be changed point by point to narrow the range to clarify the open point.
6. Check the parts prone to failure: Within the fault range, check the terminals and components prone to failure, such as loose external components such as wiring terminals, poor contact, etc. For the faults found, if they can be handled by themselves, they can be handled immediately, and then the protection that has been withdrawn is put into operation. If the open point is on the wiring terminal of the transformer body, the power should be cut off for processing. If it cannot be handled by yourself (such as inside the relay) or the fault cannot be found by yourself, the secondary of the current transformer should be short-circuited, or the load should be transferred, the power should be cut off, and the superior should be reported to send professional maintenance personnel to check and handle it.
7. Handling of special situations:
The secondary open circuit voltage is very high and personnel cannot approach: If personnel cannot approach the current transformer for short-circuit operation due to safety distance, the power must be cut off.
Internal smoke or fire: If there is smoke or fire inside the current transformer, the circuit breaker must be used to disconnect the current transformer circuit, and then the fire should be extinguished and measures should be taken to prevent the spread of the fire.