Transformer

Converting transformer is proportional voltage or current of the device. Its main function is to high voltage or high current proportionally converted into a standard

low voltage (100V) or standard small current (5A or 10A refer Ratings), in order to achieve measuring instruments, protective equipment and automatic control devices

Standardization of equipment, miniaturization. Meanwhile transformer can also be used to separate high-voltage systems, in order to ensure the safety of persons and

equipment.
Basic Introduction
Transformer (instrument transformer) is proportional voltage or current of a transformation. Its main function is to high voltage or high current proportionally

converted into a standard low voltage (100V) or standard small current (5A or 1A, refer to rating), in order to achieve measurement

Instrumentation, protective equipment and automatic control equipment standardization, miniaturization. Meanwhile transformer can also be used to separate high-voltage

systems, in order to ensure the safety of persons and equipment. In proportion to the voltage or current of a transformation.
Key Features
(1) a primary winding connected in series in the circuit, and rarely turns, therefore, a current in the coil depends entirely on the load current of the circuit under

test. And has nothing to do with the secondary current; (2) current transformer secondary coil connected instruments and relay current coil impedance is very small

Therefore, under normal circumstances, the current transformer at a near short-circuit state operation.
A current transformer secondary rated current ratio, known as mutual inductance Rated current transformer ratio: kn = I1n/I2n
Because the primary winding rated current I1n been standardized, unified secondary winding rated current I2n 5 (1 or 0.5) An, so the mutual inductance Rated current

transformer ratio has been standardized. kn can be approximated as a transformer primary and secondary winding turns ratio, i.e. kn ≈

kN = N1/N2 where N1.N2 as one, two coil turns.
History
Transformers first appeared in the 19th century. With the development of power transformers industry, transformer voltage levels and accurate level has greatly improved, but also

developed a lot of special transformers such as voltage, current hybrid transformer, DC current transformers, high accuracy current

Ratio and voltage ratio control, high current laser-type current transformers, electronic circuit compensation transformer, high voltage systems photoelectric

transformer, and SF6 enclosed Switchgear (GIS) in the voltage and current transformers. In the electric transformer industry, to develop what voltage

Grade and size of the power system, must develop the appropriate voltage level and accuracy of transformers for power system measurement, protection and control needs.
With many of the continuous application of new materials, transformers also appeared many new types of electromagnetic transformer has been more fully developed, in

which the core current transformer with dry, oil-filled and gas-insulated variety of structural formula adapted to the development needs of electric power construction

. However, with the power transmission capacity is growing, increasing the grid voltage level of continuous improvement and protection requirements, the general

structure of iron-core current transformers have been incompatible with gradually exposed the weaknesses inherent bulky, magnetic saturated ferromagnetic resonance

Vibration, the dynamic range is small, the use of narrow band and other weaknesses, it is difficult not meet the new generation of full power system automation, power

digital network development needs.
With the rapid development of optoelectronic technology, many technology developed has turned to the use of optical sensor technology and electronics to develop new

methods of electronic current transformer, referred to as optical current transformer. International Electrotechnical Commission has released an electronic current

transformer

Standards. Meaning electronic transformer, in addition to including the photoelectric transformer, but also a variety of other electronic test principle using the

voltage and current sensors.