How to handle an open circuit on the secondary side of a current transformer in an emergency?
Dec 10, 2025| 1. Immediately disconnect power and deactivate protection: Upon discovering an open circuit, immediately disconnect the power supply to the relevant equipment and deactivate any potentially malfunctioning protection devices.
If the ammeter displays abnormally or the protection device issues a disconnection signal, prioritize disabling the relevant protection devices.
2. Safety precautions: Operators must wear insulated gloves, stand on an insulated mat, and use insulated tools.
If the transformer is severely damaged (e.g., smoking, abnormal noise), the load must be transferred or the power supply deactivated.
3. Short-circuit the secondary winding: Reliably short-circuit the secondary side at the nearest test terminal using a jumper wire to eliminate the high voltage.
If sparks are generated during short-circuiting, the fault point is below the short-circuit point; if there are no sparks, the fault point may be in the upstream circuit.
4. Troubleshooting and repair: Check easily loosened parts (such as terminals, poor contact points); external problems can be addressed immediately.
If the open circuit point is at the transformer body terminals, power must be deactivated.
5. Recording and Reporting: Record the handling process, report the incident, and prevent similar problems from recurring.
Precautions: The secondary side must never be opened, otherwise a high-voltage hazard will occur.
During the handling process, meters must be continuously monitored to prevent the fault from escalating.
