Dry Type Electrical Transformers Winding

There are many types of dry type electrical transformers, and the winding is an important part of the dry-type transformer, which stabilizes the circuit and voltage during the operation of the dry-type transformer. The winding of the dry-type transformer is inside the dry-type transformer, and its structure is complex. Lets take a look at it:

Cylindrical winding

It is a cylindrical helix whose turns are made of flat wire wound next to each other. The cylindrical winding can be wound into a single layer; it can also be wound into a double layer. Usually always try to avoid the use of single-layer cylinders, and instead wind them into double-layer cylinders. Because when the wire is wound into a single layer, the wire is affected by elastic deformation, and the coil is easy to loosen, so that the end turns are not close enough to each other; when it is wound into a double layer, the tendency to loosen is much smaller. When the current is large, each turn is also formed by winding several wires in parallel along the axial direction, but the number of parallel wires is usually not more than 4 to 5. The contact area between the cylindrical winding and the cooling medium is large, so the cooling conditions are better, but its mechanical strength is weak, and it is generally suitable for low-voltage windings of dry type electrical transformers with small capacity.

helical winding

Dry-type transformers with slightly larger capacity have few low-voltage winding turns (less than 20 to 30 turns), but the current is large, so the cross-section of the turns is required to be large, so a lot of wires (6 or more) are used. many) are wound in parallel. In a cylindrical winding, many wires cannot be wound in parallel, because these wires are wound one by one in the same layer, and the result is that the pitch of the turns is too large, and such a coil is very unstable. , and the height is not well used, so it is not suitable to use cylindrical windings when there are many parallel wires, so spiral windings appear, as shown in the figure. It is stacked and wound one by one in the radial direction. Instead of abutting against each other like cylindrical windings, the individual spirals have an empty channel in between. When there are more parallel wires in the helical winding, the wires can be divided into two groups, thus becoming a double helix. When the temperature rise and insulation conditions permit, the helical winding can adopt a structure in which normal width oil passages and small oil passages are alternately wound, and the width of the small oil passage is about half of the normal oil passage width (about 1.5-2mm ), so it is called a half helix. When the winding is a single helix, it is called a single half helix; when the winding is a double helix, it is called a double half helix. The space utilization rate of this half-spiral winding is relatively high, and it is widely used in large and medium-sized dry type electrical transformers.