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# Precision current transformer core working principle

2019-04-04 10:12:12

In the power generation, substation, transmission, distribution and power lines the size of the current gap, from a few to tens of thousands of ampere.In order to facilitate the measurement, protection and control needs to be converted into a more uniform current, in addition, the line voltage is generally relatively high such as direct measurement is very dangerous.The precision current transformer core plays the role of current conversion and electrical isolation.

For the pointer ammeter, the secondary current of the precision current transformer core is mostly of ampere level.For digital instruments, the sampling signal is generally milliampere-level.The secondary current of the miniature ct is milliampere-level, which ACTS as a bridge between the large ct and sampling.

Miniature current transformers are also called instrument current transformers.(" instrument current transformers "have one meaning: multi-current ratio precision current transformers used in the laboratory, which are generally used to expand the instrument range.)

Similar to a transformer, the precision current transformer core works on the principle of electromagnetic induction.The precision current transformer core is connected to the winding of the measured current (the number of turns is N1), which is called the primary winding (or primary side winding or primary winding).The winding connected to the measuring instrument (N2 number of turns) is called the secondary winding (or side winding, secondary winding).

The current ratio of the primary winding current I1 to the secondary winding current I2 of the precision current transformer core is called the actual current ratio K.The rated current ratio of the current transformer operating at the rated current is called the rated current ratio of the current transformer, expressed by Kn.

Kn=I1n/I2n

The function of the precision current transformer core is to convert the primary current with a large value into the secondary current with a small value through a certain ratio, which is used for protection, measurement and other purposes.A current transformer with a transformer ratio of 400/5 can convert an actual current of 400A into a current of 5A.