Protective miniature current transformers can be divided into different types, which mainly include three categories: overload protection current transformers, differential protection current transformers and ground protection current transformers (zero-sequence current transformers). Under normal circumstances, the miniature current transformer for protection is mainly cooperated with the relay device to provide signal to the relay device to cut off the fault circuit in case of short circuit overload and other faults in the line, so as to protect the safety of the power supply system.

Then, what are the working conditions and operation requirements of miniature current transformers for protection? In practice, the protective transformer only begins to work effectively when the current is several times larger than the normal current. Therefore, one of the main requirements for it is reliable insulation performance, the other is to have enough accurate limit coefficient and enough thermal stability and dynamic stability.

In general, the primary current of the protective miniature current transformer can meet the basic requirement of the accuracy level under the rated load condition, namely the rated accurate limit primary current. The accurate limit coefficient is the ratio of rated accurate limit primary current to rated primary current. When the primary current is large enough, the core will saturate and cannot reflect the effect of the primary current. The accurate limit coefficient represents this characteristic.

In addition, it is necessary to determine the exact grade of miniature current transformers for different application requirements. The accuracy level of the transformer for protection is 5P and 10P, which means that the allowable current error at the rated accuracy limit of the primary current is 1% and 3%, and the compound error is 5% and 10% respectively. The current transformer for protection must bear the heat and electromagnetic force generated by the impact current when the line is faulty.

We manufacture various precision current transformers and voltage transformers, which are widely used in electric power, energy, telecommunication, railway, industrial control and other fields.

If you have any needs, pls be free to contact us, we welcome customers to customize.

Email: sales008@mycoiltech.com

Sales engineer: Bob Bao

Tel: +86 551 6291 5885