The Different Performance of Measuring Current Transformers and Protective Current Transformers October 9,2022.

What are the differences between measuring current transformers and protective current transformers?


Many friends don't know the difference between measurement using current transformer and protection current transformer, but in fact they all work in the same way, The electromagnetic induction of the current transformer used for measurement will be directly displayed on the ammeter, while the current transformer used for protection is different. When the current is too large, the contactors and circuit breakers will be controlled through the relay between them, and the power supply will be directly cut off. In this way, the line and equipment can be effectively protected.

Main protection in the use of current transformer winding is when fault occurs in the system can play a role, because a short circuit fault current will become very big, will be higher than normal rated current dozens of times, so it is very big current, for current transformer on the protection of the winding can be equipped with the appropriate measurement accuracy, Make the protective device work properly. The 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 fault such as short circuit and overload, so as to protect the safety of the power supply system. The working condition of the miniature current transformer for protection is completely different from that for measurement. The miniature current transformer for protection only begins to work effectively when the current is several times larger than the normal current.

The current transformers used for measurement and calculation are basically secondary windings, the key to ensure the load current can finish the work in the normal range of rated current, and the accuracy of measurement to guarantee, but when the system short circuit current transformer primary and secondary value will certainly far more than the rated current, So measurement and measurement error of the secondary winding even appeared a lot of, also won't have any actual effect, mainly is because short circuit time is shorter, and protection device has been tripped, so the measurement and measurement in the secondary winding of current transformer, can accurately reflect the accuracy of measurement, so the accuracy of the secondary winding level appear different, Then the whole way of measuring and measuring things will be different. The current transformer for measurement is mainly used to measure current, voltage and power when the line is in normal working condition, in conjunction with the measuring instrument. Main requirements of miniature current transformers for measurement:


Ⅰ. Reliable insulation;

Ⅱ. high enough measurement accuracy;

Ⅲ. The transformer should be saturated within the appropriate range (such as 500% of the rated current) to protect the measuring instrument when the fault of the measured line occurs.




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


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