You may have heard of the current transformer, it is a commonly used equipment. The function is to convert a large primary current into a small secondary current through a certain transformation ratio for protection, measurement and other purposes. For example, a current transformer with a transformation ratio of 400/5 can convert a current of 400A into a current of 5A.

So what principle does this current transformer work on?

The principle of current transformer is based on the principle of electromagnetic induction. The current transformer is composed of a closed core and a winding. The number of turns of its primary winding is very small, and it is connected in the line of current to be measured, so it often has all the current of the line flowing through. The number of turns of its secondary winding is relatively large, and it is connected in series in the measuring appearance and maintenance circuit. When the current transformer is in operation, its secondary circuit is always closed, so the impedance of the series coil of the measuring appearance and maintenance circuit is very small, the operation state of the current transformer is close to short circuit. The current transformer converts a large current on the primary side into a small current on the secondary side for use, and the secondary side cannot be opened.