What are the consequences of incorrect wiring of current transformers?

1. Impact on measurement accuracy:
Current measurement error: Reversed polarity will cause the secondary current direction to be opposite to the primary current, resulting in deviations in the measured value.
Power measurement error: Active/reactive power meters rely on the phase relationship between current and voltage; reversed polarity will change the phase, leading to incorrect power factor judgment.
Abnormal energy metering: In billing metering, reversed polarity may cause the energy meter to undercount or reverse count, resulting in electricity bill losses.
2. Impact on protection devices:
Maloperation: In differential protection, inconsistent polarity of the current transformers on both sides will increase the differential current, triggering the protection device to trip incorrectly.
Failure to operate: In case of a fault, the protection device may fail to operate in time due to incorrect signals, expanding the scope of the accident.
3. Threat to system safety:
High voltage risk: If the secondary side is open-circuited, core saturation will generate thousands of volts of high voltage, endangering personal and equipment safety.
Overheating damage: After an open circuit, core losses increase, which may lead to overheating and burnout of the windings.
4. Special scenario explanation:
Pointer-type instruments: When only measuring AC current, reversed polarity has no effect (because there is no directionality).
New energy systems: The current direction is opposite to traditional power systems, making incorrect wiring more likely; special attention should be paid to polarity matching.
Recommended correct operation:
Confirm the P1/S1 corresponding terminals (subtractive polarity) before wiring.
The secondary side must be grounded at one point to prevent high voltage from entering.
When disassembling and assembling, first short-circuit the secondary circuit with a shorting strip to avoid open circuit.