Emergency handling measures for open circuit on the secondary side of a current transformer
May 11, 2026| 1. Quickly Identify Open Circuit Phenomena
Secondary instruments (ammeter, energy meter) reading zero or fluctuating violently
Hear a buzzing or hissing sound from the current transformer
Smell a burning odor, or observe sparks or smoke at the terminal blocks
2. Immediately Report and Request a Power Outage (Safest Method)
Report to the on-duty supervisor or dispatcher immediately to cut off the primary power supply as quickly as possible, fundamentally eliminating the high-voltage threat. This is especially suitable for high-voltage systems or situations where the fault point cannot be accessed.
3. If live handling is necessary, perform a safe short circuit. When the load cannot be immediately transferred or a power outage would affect system operation:
Wear insulating protective equipment: Wear insulating gloves and boots, use tools with insulated handles, and work while standing on an insulating mat.
Reliably short-circuit the secondary winding: At the terminal block or test terminal, use a dedicated shorting clip or copper wire with a cross-section of not less than 2.5mm² to reliably short-circuit terminals S1-S2, ensuring a firm contact and avoiding loose connections and arcing.
Confirm the risk is eliminated after short-circuiting: After completion, the high voltage will immediately disappear, and the subsequent troubleshooting phase can begin.
4. Strictly Prohibited Dangerous Operations
Do not touch the secondary terminals or wires directly with your hands.
Do not use a regular multimeter to measure open-circuit voltage.
Do not attempt to tighten loose screws without short-circuiting.
5. Follow-up Handling and Restoration
Even after short-circuiting, power should be shut down as soon as possible to locate and repair the open circuit point (e.g., loose terminals, broken wires).
After repair, restore the secondary circuit connection first, then remove the short-circuit wire.
Check the current transformer for overheating or unusual odors; it can only be put back into operation after confirming it is normal.
