Why can’t the current transformer run open circuit?

There are many types of current transformers, the most used is electromagnetic current transformers, which can be divided into measuring current transformers and protective current transformers. Of course, this type of current transformer cannot be operated in an open circuit. . So why is this? Next, the editor will tell you in detail, let’s take a look.

The structure of electromagnetic current transformer is similar to that of general power transformer. It is also composed of iron core and coil. The difference between them is that the primary coil of current transformer is high current and high voltage, and the secondary coil and low voltage measuring instrument or relay The current coils are connected, and the transformer is close to a short-circuit state.

When the current transformer is in operation, the secondary circuit must not be opened, because when the current transformer is in normal operation, its primary magnetic potential and secondary magnetic potential are balanced with each other, the magnetic potential of the excitation is very small, and the magnetic density in the iron core The induced electromotive force in the secondary coil and the secondary coil are not high. If the secondary coil is open, all the primary magnetic potential is used for excitation, the iron core will be deeply saturated and the magnetic density will increase to a flat top state. The open secondary coil will produce a sharp peak The induced electromotive force with high amplitude, that is to say, the secondary coil will produce a high overvoltage. This high voltage causes great danger to electrical equipment and personal safety. At the same time, after the secondary circuit is open, the iron core will be severely saturated, causing overheating and burning the current transformer. Therefore, during operation, the secondary circuit of the current transformer is never allowed to open.