Communicate the basic principles of work generated in the work of current transformers

　　 There is a big difference in the current size in the roads of power generation, transformers, transmission and distribution, power distribution equipment, and electricity consumption, ranging from a few amperes to more than 100,000 amperes. In order to facilitate the measurement, protection and manipulation, it is necessary to transform it into a more consistent current. In addition, the operating voltage on the road is generally relatively high. It is very dangerous to measure immediately. The communication current transformer has the practical effect of current conversion and electrical equipment protection [1].

　　 Regarding pointer type ammeters, most of the secondary current of the communication current transformer is ampere level (such as 5A, etc.). Regarding the intelligent appearance, the sampled data signal is generally mAh (0-5V, 4-20mA, etc.). The secondary current of the small communication current transformer is mAh, which is crucial for the actual effect of the highway bridge between the large voltage transformer and the sampling.

　　Small communication current transformer or many people call it “instrument communication current transformer”. (The practical meaning of “communication current transformer for instrument” is that the multi-current ratio high-precision communication current transformer used in the laboratory is generally used to expand the external measurement range.)

　　 The communication current transformer and the transformer are similar to work based on the magnetic effect of the current. The transformer converts the operating voltage and the communication current transformer converts the current. The winding of the communication current transformer connected to the measured current (the number of turns of the coil is N1) is called the primary winding (or primary winding, the primary and secondary winding); the winding (the number of turns of the coil is N2) that is connected to the measuring surface is called the second Secondary winding (or secondary winding, secondary winding). Communication current transformer

　　 The current ratio between the primary winding current I1 and the secondary winding I2 of the current transformer is called the actual active current ratio K. The current ratio of the communication current transformer when operating at the rated current is called the rated current ratio of the communication current transformer, expressed in Kn.

　　Kn=I1n/I2n

　　 The actual effect of a current transformer (commonly known as CT) is to convert a primary current with a large nominal value into a secondary current with a smaller nominal value according to a certain transformation ratio, which is used for main purposes such as protection and measurement. For example, a communication current transformer with a variable ratio of 400/5 can change a current of 400A into a current of 5A.