Principles and uses of transformers
In the power supply lines, the current difference ranges from a few amps to tens of thousands of amps, and the voltage difference ranges from a few volts to millions of volts. The current and voltage in the line are relatively high, and it is very dangerous to measure them directly. In order to facilitate the conversion of secondary instrument measurement into a relatively uniform current and voltage, a transformer is used to convert current, voltage and electrical isolation.
Most display instruments are pointer-type current and voltage meters, so most of the secondary currents of current transformers are ampere-level (such as 5, etc.). With the development of the times, most power measurements have become digital, and the signals sampled by computers are generally in the milliamp level (0-5V, 4-20mA, etc.). The secondary current of the micro current transformer is milliamp level, and it mainly serves as a bridge between the large transformer and sampling. Micro current transformers are called "instrument current transformers". ("Instrument current transformer" has a meaning that is a multi-current ratio precision current transformer used in the laboratory, generally used to expand the instrument range.)
Current transformer principle circuit diagram Micro current transformers are similar to transformers and work based on the principle of electromagnetic induction. Transformers transform voltage while micro current transformers transform current. Winding N1 is connected to the measured current and is called the primary winding (or primary winding or primary winding); 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 and the secondary winding I2 of the micro current transformer is called the actual current ratio K. The current ratio of a micro current transformer when it operates at the rated operating current is called the rated current ratio of the current transformer, expressed in Kn. Kn=I1n/I2n.
