Current transformer principle works

In power transformers generation, transformation, transmission, distribution and electricity lines in the current size of the gap, from a few to tens of thousands Ann Ann has. For ease of measurement, protection and control needs to be converted to more uniform current, the voltage on the other line higher than the general risk, such as direct measurement is

Insurance. Current transformer to play the role of current transformation and electrical isolation.
For Analog ammeter, current transformer secondary current most amp level (eg 5A, etc.). For digital instrument, the sampled signal is generally mA level (0-5V ,4-20mA, etc.). Micro current transformer secondary current of milliamps, mainly from the large

Transformer and a bridge between samples.
Micro current transformer was also known as "Instrument current transformers." ("Instrument current transformer" There is a layer of meaning is more current than laboratory use precision current transformer, generally used to expand the range of the instrument.)
Current transformers and transformer similar work is based on the principle of electromagnetic induction, the transformer transforms the voltage current transformer transforms the current Bale. electric transformer connected to the measured current winding (number of turns N1), called the primary winding (or primary winding, the primary

Winding); measuring instrument connected winding (number of turns N2) is called the secondary winding (or the secondary winding, secondary winding).
Current transformer primary winding and the secondary winding current I1 I2 current ratio, called the actual current ratio K. Current transformer at rated current work of the current ratio is called the current transformer rated current ratio, expressed by Kn.
Kn = I1n/I2n
Current Transformer (Current transformer referred CT) role is to put a value larger than the current through a certain variable values ??into smaller secondary current, used for protection, measurement and other purposes. If ratio of 400/5 current transformer, can be

To be effective for the conversion of 5A to 400A current.