An introduction to compensation methods for AC current transformers

1. Magnetic potential compensation method

In the core of the current transformer transformer, an additional winding is added to show the magnetic potential to this winding, and this additional magnetic potential is used to compensate the error of the current transformer.

(1) Turns compensation. When the primary ampere-turn of the current transformer is fixed, calculate I, N, = I2N2 from the formula to know that the amount of secondary current is inversely proportional to the number of secondary turns, reducing the number of secondary turns will increase the amount of secondary current, on the contrary When the number of secondary turns is enlarged, the amount of secondary current will decrease, so that the ratio difference of the transformer can be compensated.

(2) Secondary winding series capacitor compensation. A capacitive magnetic potential is generated in the secondary series capacitor of the current transformer to compensate for changes in the angular error caused by changes in the secondary load and power factor.

2. Electromotive force compensation

The additional working voltage or electromotive force will be immediately added to the secondary winding of the current transformer to compensate for the error of the current transformer.

(1) Magnetic shunt compensation. The outer multi-layer ferrite core is wound by two less turns, so that the two turns are saturated first, which is used to compensate the error of 1%-10% of the exit current of the transformer, and straighten the error curve of the ratio.

(2) Magnetic shunt short-circuit fault turn compensation. The short-circuit fault turns of WeChat friends are added to the magnetic shunt, and the loss angle of the magnetic shunt is increased to compensate for the difference between the corners.