Cable Crossing Tubes

Product Overview

The current transformer principle is based on the principle of electromagnetic induction. The current transformer is composed of a closed core and windings. Its primary winding turns are few, strung in the line of the current to be measured, so it is often all the current flow through the line, the secondary winding turns are more, connected in series in the measuring instrument and protection circuit, the current transformer in the work, its secondary circuit is always closed, so the measuring instrument and the protection circuit of the series coil of the impedance is very small, the current transformer's working condition is close to a short-circuit.

Working Principle

In the power generation, substation, transmission, distribution and electricity lines in the current size, from a few amps to tens of thousands of amps. In order to facilitate the measurement, protection and control needs to be converted to a more uniform current, in addition to the line voltage is generally higher such as direct measurement is very dangerous. Current transformers play a role in current conversion and electrical isolation.

For pointer type ammeters, the secondary current of the current transformer is mostly of the ampere class (e.g. 5A, etc.). For digital meters, the signals sampled are generally milliamperes (0-5V, 4-20mA, etc.). Miniature current transformer secondary current for the milliampere level, mainly as a bridge between the large transformer and sampling.

Miniature current transformer is also known as the “instrumentation current transformer”. (“Instrumentation current transformer” has a layer of meaning is used in the laboratory than the multi-current precision current transformer, generally used to expand the instrument range.)

Current transformers and transformers are similar to work according to the principle of electromagnetic induction, the transformer transforms the voltage and the current transformer transforms the current. Current transformer connected to the measured current winding (turns for N1), known as the primary winding (or primary winding, primary winding); connected to the measuring instrument winding (turns for N2) known as the secondary winding (or secondary winding, secondary winding).

Current transformer primary winding current I1 and secondary winding I2 current ratio, called the actual current ratio K. Current transformer in the rated current work under the current ratio called current transformer rated current ratio, with Kn said.

Kn=I1n/I2n

Current transformer (Current transformer abbreviated as CT) is the role of a larger value of the primary current through a certain ratio converted to a smaller value of the secondary current, used for protection, measurement and other purposes. Such as the ratio of 400/5 current transformer, the actual 400A current can be transformed into 5A current.