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What is a current transformer?

What is a current transformer ?


The current transformer is to convert the large current on the primary side into a small current on the secondary side for measurement, and the secondary side cannot be opened.

A current transformer is an instrument that converts a large current on the primary side into a small current on the secondary side for measurement based on the principle of electromagnetic induction.

A current transformer consists of a closed iron core and windings. Its primary side winding has few turns, and it is connected in the line of the current that needs to be measured.

Therefore, it often has all the current of the line flowing through it, and the secondary winding has a large number of turns. It is connected in series in the measuring instrument and the protection circuit. When the current transformer is working, its secondary circuit is always closed, so the measurement The impedance of the series coil of the instrument and the protection circuit is very small, and the working state of the current transformer is close to a short circuit.
In the lines of power generation, substation, transmission, distribution and consumption, the current varies greatly, ranging from a few amperes to tens of thousands of amperes. In order to facilitate measurement, protection and control, it needs to be converted into a relatively uniform current. In addition, the voltage on the line is generally relatively high, such as direct measurement, which is very dangerous. The current transformer plays the role of current transformation and electrical isolation

For pointer-type ammeters, most of the secondary currents of the current transformers are in the ampere level (such as 5A, etc.). For digital instruments, the sampled signal is generally at the milliamp level (0-5V, 4-20mA, etc.). The secondary current of the miniature current transformer is milliampere, which mainly acts as a bridge between the large transformer and the sampling.


According to different uses, 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, metering and other devices within the normal working current range.

Current transformer for protection (or protective winding of current transformer): In the state of grid fault, it provides grid fault current information to relay protection and other devices.

The protection current transformers are divided into: 1. overload protection current transformers, 2. differential protection current transformers, 3. grounding protection current transformers

The protective current transformer mainly cooperates with the relay device, and provides a signal to the relay device to cut off the fault power when a fault such as a short-circuit overload occurs in the line.


Premier Cable make a lot of compatible Pika Current Transformer Kit and Generac Current Transformer Kit


You can see the products details from below link :


Generac Current Transformer


Pika Current Transformer Kit


Generac Current Transformer Kit




Pika - Model CT - Adding Current Transformers Kit


Generac APKE00006 PWRcell 600A Current Transformer Kit


Generac UCT2 PWRview Smart Universal Current Transformers


If you need product details, drawings, and samples, you can use below contact info : 


Skype : James198585 


Wechat : 13929497934

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