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Current Transformer

China Current Transformer, Find details about China Current Transformer, CT from Current Transformer

Model NO.
Current transformer
Insulating Medium
Epoxy Resin
Installation
Busbar Type
Magnetic Circuit Structure
Combined Type
Voltage Transformation Principle
Photoelectric Type
Trademark
Jingcheng
Transport Package
Wooden Box
Specification
10-35kV
Origin
Hangzhou
HS Code
85043110
Model NO.
Current transformer
Insulating Medium
Epoxy Resin
Installation
Busbar Type
Magnetic Circuit Structure
Combined Type
Voltage Transformation Principle
Photoelectric Type
Trademark
Jingcheng
Transport Package
Wooden Box
Specification
10-35kV
Origin
Hangzhou
HS Code
85043110
Current transformer
Current transformer is an instrument which converts the large current in primary side into small current in secondary side according to the principle of electromagnetic induction. The current transformer is composed of closed core and winding. Its primary winding turns are very few, and it is connected in series in the circuit which needs to measure the current.
Therefore, it often has all the current flowing through the line, and the secondary winding turns are more. It is connected in series in the measuring instrument and protection circuit. When the current transformer is working, its secondary circuit is always closed, so the impedance of the series coil of the measuring instrument and protection circuit is very small, and the working state of the current transformer is close to short circuit. The current transformer converts the large current at the primary side into the small current at the secondary side for measurement, and the secondary side cannot be opened.
Basic concepts
The principle of current transformer is based on the principle of electromagnetic induction. The current transformer is composed of closed core and winding. Its primary winding turns are very few, and it is connected in series in the line that needs to measure the current, so it often has all the current flowing through the line. The secondary winding turns are relatively large, and it is connected in series in the measuring instrument and protection circuit. When the current transformer is working, its secondary circuit is always closed, so the impedance of the series coil of the measuring instrument and protection circuit is very small, and the work efficiency of the current transformer is very low The working state is close to short circuit.
working principle
In the lines of power generation, transformation, transmission, distribution and consumption, the current varies from several to tens of thousands of amperes. In order to facilitate the measurement, protection and control, it needs to be converted to a more unified current. In addition, the voltage on the line is generally high, so it is very dangerous to measure directly. Current transformer plays the role of current conversion and electrical isolation.
For pointer type ammeter, the secondary current of current transformer is mostly ampere level (such as 5a, etc.). For digital instruments, the sampling signal is generally Ma level (0-5V, 4-20mA, etc.). The secondary current of micro current transformer is Ma level, which mainly acts as a bridge between large current transformer and sampling.
Micro current transformer is also called "instrument current transformer". (the meaning of "instrument current transformer" is multi current ratio precision current transformer used in laboratory, which is generally used to expand the instrument range.)
The current transformer is similar to the transformer. It works according to the principle of electromagnetic induction. The transformer transforms the voltage while the current transformer transforms the current. The winding of current transformer connected to the measured current (number of turns is N1) is called primary winding (or primary winding or primary winding); the winding connected to measuring instrument (number of turns is N2) is called secondary winding (or secondary winding or secondary winding).
The current ratio of primary winding I1 to secondary winding I2 of current transformer is called actual current ratio K. The current ratio of current transformer working at rated current is called rated current ratio of current transformer, expressed by kn.
Kn=I1n/I2n
The function of current transformer (CT) is to convert the primary current with larger value into the secondary current with smaller value through a certain transformation ratio for protection, measurement and other purposes. For example, the current transformer with the transformation ratio of 400 / 5 can convert the actual current of 400A into 5A.
Classification by use
According to different applications, current transformers can be roughly divided into two categories:
Measuring current transformer (or measuring winding of current transformer): provide current information of power grid to measuring and metering devices within normal working current range.
Current transformer for protection (or protection winding of current transformer): in case of power grid fault, it provides power grid fault current information to relay protection and other devices.

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