Solution to the secondary open circuit of CT of current transformer

1. The indicator of the loop instrument is abnormal, which is generally reduced or zero. The open circuit of the current loop used to measure the meter will cause the three-phase ammeter indications to be inconsistent, the power meter indication will decrease, and the meter will turn

Slow or no rotation. If there is sometimes no indication from the meter, it may be in a semi-open state (poor contact).

2. Whether the CT body of the current transformer has noise, uneven vibration, severe heating, smoke, etc., of course, these phenomena are not obvious when the load is small

3. Current transformer CT secondary circuit terminals and component wires are discharged and sparked.

4. Misoperation or refusal of relay protection occurs. This situation can be found and dealt with when accidental or over-level tripping occurs.

5. The watt-hour meter, relay, etc. burn out due to smoke. The burnout of reactive power meters and watt-hour meters, transmitters of remote control devices, and relays of protection devices will not only make the CT secondary open circuit, but also make the PT secondary short circuit.

Conclusion and troubleshooting:

The above are some basic clues to check the secondary open circuit of CT. In fact, in normal operation, the primary load is not large, the secondary does not work, and it is not the current mutual inductance when the current loop for measurement is open.

It is not easy to find the secondary open circuit fault of the model CT. Check and handle the current transformer CT secondary open circuit fault, try to reduce the primary load current to reduce the voltage of the secondary circuit. Fuck

Pay attention to safety when working, stand on an insulating mat, wear insulating gloves, and use well-insulated equipment.

(1) When the CT secondary open circuit is found, it is necessary to distinguish which group of current circuit faults, the difference of the open circuit, whether it affects the protection, report the dispatch, and remove the protection that may malfunction.

(2) Try to reduce the primary load current. If the CT is severely damaged, the load should be transferred and the power cut should be handled. The principle of the current transformer CT secondary overvoltage protector to prevent the current transformer CT from secondary open circuit

(3) Try to short-circuit the CT secondary as soon as possible with a good short wire on the nearby test terminal according to the drawing, and then check and deal with the open circuit point.

(4) If sparks are found during the short-circuit connection, the short-circuit connection should be effective, and the fault point should be in the circuit below the short-circuit point, which can be further searched. If there is no spark when short circuit, then ONLINE

Short-circuit is invalid, the fault point may be in the circuit before the short-circuit point, and the short-circuit point can be changed point by point to reduce the scope of inspection.

(5) In the fault range, check the terminals and components that are prone to faults. It can handle the faults detected by itself, such as loose connection terminals and other external components, poor contact, etc.

After processing immediately, put in the protection that was withdrawn. If the open circuit point is on the terminal of the current transformer model body, the power supply should be cut off. If it cannot be handled by itself (such as inside the relay) or cannot

If you find out the fault by yourself, you should first short-circuit the CT secondary and then report to the superior.