What Is the Current Transformer (CT)?
A current transformer is a current transformation device (also called CT). Its main function is to convert high-voltage current and low-voltage large current into small current with lower voltage, supply the meter and protection device, and separate the meter and protection device from the high-voltage circuit. Next, let's learn about the role of current transformers, current transformer models, and current transformer transformation ratios.
What is a circuit transformer?
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 is connected in the line of the current to be measured.
Therefore, it often has all the current of the line flowing, 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. Therefore, the impedance of the series coil of the measuring instrument and the protection circuit is very small, and the working state of the current transformer is close to a short circuit. 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.
The role of current transformers:
The function of the current transformer is to convert the primary current with a larger value into a secondary current with a smaller value through a certain transformation ratio, which is used for protection, measurement and other purposes. For example, a current transformer with a ratio of 400/5 can convert an actual current of 400A into a current of 5A.
Type of CT
Model meaning
The first letter: L—current transformer.
The second letter: A-through-the-wall type; Z-pillar type; M-busbar type; D-single-turn penetration type; V-structure inverted type.
The third letter: Z - epoxy resin casting type; C - porcelain insulation; Q - gas insulating medium; W - dedicated to the protection of microcomputers.
