Dry type transformer winding

It is a cylindrical spiral body, and its turn is made by flat wires close to each other. The cylindrical winding can be wound into a single layer or a double layer. Usually, it is always avoided to use single cylinder, but to form double cylinder. Because when the wires are wound into single layer, the wires are affected by elastic deformation, so that the coils are easy to release, so that the end turns are not tight enough to each other; and when the winding is double layer, the tendency of loosening is much smaller. When the current is large, the number of parallel wires is usually less than 4-5. The contact area between the cylindrical winding and the cooling medium is large, so the cooling condition is better, but its mechanical strength is weak, which is generally suitable for low-voltage winding of dry-type transformer with small capacity.

(a) Profile (b) longitudinal section wire arrangement

Spiral winding

    The number of turns of low voltage winding of dry-type transformer with larger capacity is very small (less than 20-30 turns), but the current is very large, so the cross-section of the turn is required to be large, so many wires (6 or more) shall be used for parallel winding. In the cylindrical winding, many wires cannot be wound in parallel, because they should be arranged and wound one by one in the same layer. As a result, the pitch of the turn of the wire is too large. Such a coil is very unstable and the height is not well utilized. Therefore, it is not suitable to use the cylindrical winding when parallel wires are many, so spiral winding appears, as shown in the figure As shown in. It is folded and wound one by one in radial direction. The helixes are not close to each other like the cylindrical winding, but there is an empty channel in the middle. When the parallel wires of spiral winding are more, the wires can be divided into two groups, which makes them double helix. When temperature rise and insulation conditions permit, spiral winding can be staggered by oil channel with normal width and small oil passage. The width of small oil passage is about half of the width of normal oil passage (about 1.5-2mm), so it is called half spiral, and winding is called single and half spiral when single spiral is single spiral; when winding is double spiral, it is called double half spiral. The space utilization of this kind of semi spiral winding is relatively high, and it is widely used in large and medium dry-type transformers.

(a) Profile (b) longitudinal section wire arrangement

Continuous winding

    Continuous winding has no welding head, and can only be wound with flat wire. The inter turn arrangement of wires is shown in the figure. It is wound by special winding process. From one wire cake to another, the joints are alternately inside and outside the coil, but they are connected naturally by the wires of winding coil. Therefore, there is no welding head, which is the main advantage of continuous winding.

If the cross-section of the conductor is large, several wires can be wound in parallel, generally not more than 4 wires, and the position shall be changed while winding.

The above content is about the dry-type transformer winding related introduction. For dry-type transformer, if you have other problems or doubts, you can log on our website for consultation in the section 15862117532 or consult.