What are the dangers of an open circuit on the secondary side of a Power Current Transformer?

1. High voltage generation
When the Power Current Transformer is working normally, the magnetic flux generated by the secondary current and the magnetic flux generated by the primary current cancel each other out, and the magnetic flux density in the iron core is low. Once the secondary side is open, the secondary current becomes zero, and the magnetic flux that cancels the primary magnetic flux cannot be generated, resulting in a sharp increase in the magnetic flux in the iron core, a sharp increase in the magnetic flux density, and rapid saturation of the iron core. According to the law of electromagnetic induction, a saturated iron core will induce an extremely high electromotive force in the secondary winding, which can reach thousands of volts or even tens of thousands of volts, posing a serious threat to the insulation of equipment in the secondary circuit and the safety of operators.
2. Overheating of the iron core
Due to the open circuit on the secondary side, the magnetic flux density in the iron core increases, and the hysteresis loss and eddy current loss also increase sharply, causing the iron core to overheat. Long-term overheating will reduce the insulation performance of the iron core, accelerate insulation aging, and may even cause the iron core to burn out, thereby affecting the normal operation of the Power Current Transformer. In severe cases, it will also cause damage to the transformer, requiring replacement or repair.
3. Increased measurement and metering errors
The secondary side of the Power Current Transformer provides current signals for measuring instruments and metering devices. The open circuit on the secondary side will prevent the secondary current from being transmitted normally, resulting in the inability of the measuring instruments and metering devices to accurately measure the current value on the primary side. This will not only make the measured data meaningless, but also affect the accurate judgment of the operating status of the power system and the accuracy of electric energy metering, and thus affect the fairness and rationality of related work such as electricity bill settlement.
4. Affect the normal operation of relay protection devices
In the power system, the Power Current Transformer provides current signals for the relay protection device to determine the occurrence of faults and trigger protection actions in time. The open circuit on the secondary side will cause the current signal received by the protection device to be abnormal, which may cause the protection device to misjudge or refuse to operate. For example, in the event of a short circuit fault, since the open circuit on the secondary side of the Power Current Transformer cannot accurately reflect the fault current, the protection device may not be able to detect the fault and operate in time, thereby prolonging the fault time and expanding the fault range, which will seriously affect the safe and stable operation of the power system.