What is the role of the current transformer in detail
A current transformer is a current conversion device. It turns high voltage and low voltage large current into a lower voltage small current supply surface and relay maintenance equipment and isolates the surface and maintenance equipment from the high voltage circuit. The secondary side current of the current transformer is 5A, which makes the measurement surface and relay maintenance equipment safe and convenient to use, and also makes it standardized in production.
The structure of the current transformer is composed of an iron core, a primary winding, a secondary winding, a terminal and an insulating support. The primary winding of the current transformer has fewer turns, and it is connected in series in the line that needs to measure the current, and a larger measured current flows through it. inside.
The secondary circuit of the current transformer is not allowed to open. When the current transformer is in operation, its secondary circuit is always closed, but because the impedance of the series winding of the measuring surface and maintenance equipment is very small, the working condition of the current transformer is close to the short-circuit condition, and the magnetizing force generated by the primary current is large. Both are compensated by the secondary current, the total magnetic flux density is not large, and the secondary winding potential is not large. When the current transformer is open, the impedance of the secondary circuit is infinite, the current is equal to zero, the primary current completely becomes the excitation current, and a high potential is generated in the secondary winding, compromising personal safety, and forming the secondary insulation of the exterior, maintenance equipment, and transformers. damage.
The secondary circuit of the current transformer must be grounded to avoid the primary insulation breakdown and the secondary high voltage being connected in series, compromising personal safety and damaging the equipment.