The working principle of miniature current transformer

In power lines, currents and voltages vary widely from a few amperes to tens of thousands of amperes. In order to facilitate the measurement of the secondary instrument, it needs to be converted into a relatively uniform current. In addition, the voltage on the line is relatively high, and direct measurement is very dangerous. Current transformers serve as galvanic and galvanic isolation. The display instruments are mostly pointer-type current and voltmeters, so the secondary current of the current transformer is mostly amperes. With the development of the times, most of the electricity measurement has been digitized, and the signals sampled by the computer are generally at the milliamp level (0-5V, 4-20mA, etc.). The secondary current of the miniature current transformer is mA, which is mainly used for large-scale Bridge between transformers and sampling. Miniature current transformers are called "instrument current transformers". ("Instrument current transformer" means a multi-current ratio precision current transformer. It is used in the laboratory and is generally used to expand the measurement range of the instrument.) Similar to the transformer, the miniature current transformer also works according to the principle of electromagnetic induction. Transformers convert voltage, while miniature current transformers convert current. The winding N1 is connected to the measured current and is called the primary winding (or primary winding or primary winding); the winding N2 is connected to the measuring instrument and is called the secondary winding (or secondary winding or secondary winding). The current ratio of the primary winding current I1 to the secondary winding current I2 of the miniature current transformer is called the actual current ratio k The current ratio of the miniature current transformer when it works under the rated working current is called the rated current ratio of the current transformer, expressed by Kn . Kn=I1n/I2n