Common fault causes of current transformers

1. When using the current transformer, the body has abnormal noise, vibration and other uneven abnormal noise. This kind of failure phenomenon is not obvious under load, but after the open circuit, due to the increase of magnetic flux density and the action of non-sinusoidal magnet, the vibration of silicon steel sheet is not obvious, the sound is not uniform, causing a large noise.

2. Discharge and ignition phenomena at the terminals and component joints of the secondary circuit. When the circuit is open, due to the secondary high voltage of the current transformer, under the action of the high voltage, the joints and terminals of the secondary circuit elements of the current transformer will appear abnormal. For example, when the discharge and ignition are severe, the insulation performance of the components will be reduced, and the phenomenon of insulation breakdown will occur.

3. Line relay protection malfunctions or refuses to act. Under normal circumstances, after a false trip or rose trip accident occurs, the fault can be found and dealt with when checking the cause.

4. The circuit meter indicates abnormal drop or return to zero. If the current loop of the meter is open, it will have a certain impact on the three-phase ammeter. It can cause problems with the three-phase ammeter indication, lower the power meter indication, make the ammeter not spin or slow down. If the meter indication is sometimes unavailable, it may be in a bad contact state.

5. The current transformer body is seriously heated, accompanied by abnormal phenomena such as peculiar smell, discoloration of the shell surface, and smoke. This phenomenon is not obvious when the load is small. When the circuit is open, abnormal odor is produced due to severe magnetic saturation, severe overheating of the iron core, rising temperature of the case and heating of the internal insulation. If severe, the smoke will burn out.

6. The smoke of the instrument, watt-hour meter, relay and other components is burnt out. This condition is detected and dealt with when checking the cause after an erroneous trip or an overstep trip accident. The burnout of the components has a certain influence on the current transformer, which will cause the current transformer to be broken twice and short-circuit the current transformer twice.