How to restore the secondary side of a current transformer after it is open-circuited?
May 13, 2026| 1. Immediately Report and Request a Power Outage (Priority Solution) Upon discovering an open circuit, immediately report to the on-duty supervisor or dispatcher and request a power outage for the relevant equipment. This is the safest and most recommended method, especially suitable for high-voltage systems or situations where the fault location cannot be determined.
2. Safety Preparations If live handling is required (if immediate power outage is not possible), operators must wear insulated boots and gloves, use tools with insulated handles, and work on an insulated mat, ensuring a safe distance from live parts.
3. Reliably Short-Circuit the Secondary Side At the current transformer terminal block or test terminal, use a dedicated shorting clip or copper wire with sufficient cross-section to reliably short-circuit terminals S1-S2. Ensure good contact during short-circuiting to avoid sparks caused by loose connections.
After short-circuiting, the high voltage on the secondary side will immediately disappear, and the system will enter a safe state.
4. Locate and Repair Open Circuit Points
After short-circuiting, check the following common fault locations step by step:
Whether the terminals are loose, oxidized, or detached.
Whether the secondary conductors are mechanically damaged or broken by external force.
Whether the pressure plates on the protection panel and control panel are not tightened or accidentally disconnected.
Whether the wiring of ammeters, electricity meters, and other equipment is loose.
5. Restore the Circuit and Remove the Short-Circuit Wire
Only after confirming that the fault point has been repaired and the circuit is conductive can the secondary circuit connection be restored before removing the short-circuit wire. It is strictly forbidden to remove the short-circuit before restoring the main circuit to prevent re-opening.
6. Inspection and Commissioning
After restoration, check the current transformer for abnormal noises or overheating. Confirm that the ammeter, wattmeter, and other indicators are normal, and that the relevant protection devices have been reactivated. Only then can the problem be considered resolved.
7. Record and Report
Record the fault time, phenomena, handling process, and cause, and report to the relevant department for subsequent analysis and prevention of similar incidents.
