PCT831 DC current immunity current transformer composite cores

Electrical Specification

(Customized is available)

Rated Primary Current	50A
Max Primary Current	120A
Rated Secondary Current	25mA
Accuracy	0.1~2.0
Electrical Strength	3000VAC 1mA60s
Load Resistance	30Ω
Rated Frequency	50/60HZ

Due to the existence of the DC component of the fault current, the protective current transformer will be rapidly saturated, and the sampling value will decrease rapidly, causing the protection device to malfunction.
In most magnetic materials, due to the influence of saturation magnetic induction and remanence factors, a small DC component will saturate the transformer.
Selecting magnetic materials with high saturation magnetic induction and low remanence is the key to improving the DC resistance of the protective current transformer.
Although the silicon steel magnetic core has a high saturation magnetic induction intensity, its remanence is high, so the protective current transformer made of it is not ideal.
The DC resistance can be improved by increasing the cross-sectional area of silicon steel, but the improvement is not much, and it will be limited by the volume factor.
Silicon steel opening the air gap can greatly improve the DC resistance, but the phase difference of the protective current transformer made by it is very large (generally more than 10°), and the phase difference changes with the temperature.