The difference between the principle of voltage transformer and current transformer

- Sep 20, 2019-

The main difference is that the working state is very different during normal operation, which is expressed as:

 1) The current transformer can be short-circuited twice, but it must not be opened; the voltage transformer can be opened twice, but not short-circuited;

 2) Compared with the load on the secondary side, the primary internal impedance of the voltage transformer is small or negligible, and the voltage transformer can be considered as a voltage source; while the current transformer has a large internal resistance, so that it can be considered It is a current source with an infinite internal resistance.

 3) When the voltage transformer works normally, the magnetic flux density is close to the saturation value, and the magnetic flux density decreases when the fault occurs; the magnetic flux density is very low when the current transformer works normally, and the magnetic current becomes very large due to the primary side short-circuit current during the short circuit. The pass density is greatly increased, sometimes even far exceeding the saturation value.