Foil winding in transformer is formed by winding one or more wires together. It is a kind of layer coil. Different from the cylindrical coil, the conductor of the foil coil is thin and wide copper foil or aluminum foil, with only one turn in the axial direction and multiple turns in the radial direction. There will be an axial oil gap after winding a few turns. This structure is mainly used in transformers with low voltage and small capacity.
 
Foil winding in transformer 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 deform, and can withstand short-circuit force; Good electrical strength and uniform distribution of impulse gradient voltage; Easy winding.


 
The winding of foil winding in transformer requires a special foil coil winding machine. The foil coil winding machine is composed of coil winding machine, conductive foil (plate) material and insulation coil uncoiler, end insulation uncoiler, conductive foil (plate) material feeding device and foil plate edge trimming device, foil plate cutting device, insulation coil cutting device, TIG welding device, switch frame, control console, microprocessor, etc.
 
France, Switzerland, the United States and other countries have already produced foil coil winding machines. In recent years, China has also begun to develop foil coil winding machine. Generally, the foil coil winding machine can be divided into different specifications according to the width of the wound metal foil plate. For example, the French scal company has: 300, 650, 800, 1100 and 1500 foil winding machines, and the maximum width of the corresponding sub coiled foil is 300, 650, 800, 1100 and 1500 (mm). Using foil coil winding machine to wind foil coil has the advantages of simple operation, high degree of automation, low labor intensity and stable quality.