Foil coil is mainly used for small and medium-sized transformers with capacity less than 2000KVA. The advantages of foil coil are: good mechanical strength, not easy to deformation, can withstand short circuit force; Good electrical strength, uniform impulse gradient voltage distribution; Easy to wind.
1. Structure of foil winding
Foil windings are suitable for low voltage (hundreds of volts) and high current (hundreds of amps to thousands of amps). They are generally used as secondary windings of distribution transformers.
The foil transformer uses copper foil or aluminum foil with high conductivity as the conductive material. The thickness of copper foil or aluminum foil is about 0.1-2.5mm, and each layer of wire foil is one turn.
Conductive foil lining with insulating paper, thickness of 0.05-0.12mm, generally using rhombic point glue cable paper. High strength insulating paper should be used as interlayer insulation because the conductive foil may have metal dust on the surface and the insulating paper may have small pinholes.
The head of the conductive foil is the outgoing wire of the windings welded to the conductive foil.
2. Foil winding direction
The winding direction of the foil winding is specified: from the end of the conductive row of the lead wire, the foil rao Juan forward direction is counterclockwise, is the left winding direction; Foil Rao Juan forward direction for clockwise, that is, the right around.
According to the structure of the winding machine and the relative position of the person to the machine, it should be: the person faces the winding machine, and the leading end of the conductive row points to the right, which is the left winding direction; To the left, to the right.
3. Insulation of foil winding
Foil around the edge of one layer for a turn, the voltage between the layers for the number of volts to tens. Generally, the insulation between layers is 2 pieces of cable paper.
In order to increase the creepage distance of conductive foil, the width of inter-layer insulation should be at least 20mm wider than the width of the thin conductive foil (10mm on each side).
The end insulation may be made of a 0.5mm or 0.8mm thick reeled insulating board. A combination of these two thickness materials can be used as the end insulation of the foil winding, or the interlayer insulation can be used as the end insulation.
Where the metal foil plate is welded to the conductive row, the interlayer insulation shall be strengthened relative to another metal foil plate. The general interlayer insulation should overlap a little bit here.
4. Winding of foil winding
The foil winding must be wound with the foil winding machine, the operation is relatively simple, according to the foil winding machine operation procedures can be carried out. Foil windings may also be wound side by side or overlapped by two pieces of foil. When overlapping winding, no transposition is performed. Two sheets of metal foil overlap each other and are contained in a conductive row. When wound side by side, the gap between the two foils shall not be greater than 1mm and shall not overlap, which can be controlled by the edge adjustment brake. Automatic winding allows full use of materials. The foil winding winding machine can be wound round, rectangular or oblong. When winding rectangle or long circular winding, the winding machine must be pressed on the winding roller, so as to ensure the quality.
The height of the coil of the foil winding machine produced by our company can be from 180 to 1400mm. Single-layer foil winding or double-layer foil winding is optional. Foil winding machine series adopt PLC automatic control frequency conversion stepless speed regulation system, photoelectric hydraulic rectifying system, automatic welding mechanism and other automatic control functions. The whole machine adopts Siemens, Mitsubishi, Schneider components and control systems, effectively ensuring product quality and equipment stability.
Post time: Dec-11-2020