JPS60103604A - Multi-parallel windings having large-current capacity of transformer - Google Patents

Abstract

PURPOSE:To obtain cheap windings without making output windings largeseized by making conductivity of conductors of parallel coils positioned at both ends of multi- parallel windings having large current capacity in the axial direction higher than that of intermediate coils. CONSTITUTION:Output windings 31 are disposed concentrically outside input windings 1, and a plurality of disk-like coils, that is, coil 31a at the upper and lower ends in the axial direction and intermediate coils 31b positioned therebeteween are stacked to be connected in parallel with output buses 3 composed of (u) and (x). Copper is used for the conductors of the coils 31a at the upper and lower ends and material having conductivity lower than that of coils at the upper and lower ends, for example, aluminum is used for that of the intermediate coils 31b. The dimension of the coils 31a at the upper and lower ends in the radial direction may be made small in order to reduce eddy current loss. For the conductor of the output busses 3, aluminum is usually used from the viewpoint of workability of connection between the conductor and the buses having large current capacity and reduction in weight. Since temperature rise at winding ends is reduced, temperature rise at the whole windings is reduced and uniformed.

Description

[Detailed description of the invention] [Technical field to which the invention pertains] This invention relates to windings for low voltage, large current transformers used in chemical factories, electric furnaces, etc. Relates to multi-parallel high current windings connected in parallel.

[Prior art and its problems] ' Fig. 1 is an example of the multi-parallel large current windings of a conventional transformer of this type.One output winding 2 is arranged concentrically outside the input winding 1, and the output The winding 2 is formed by stacking a plurality of disc coils in the axial direction, each consisting of coils 2a at both axial ends and a middle coil 2b. And each disk coil 2a, 2b is u
, x are connected in parallel to the output bus 3. In this case, the currents shared by the disk windings 2a, 2b are distributed as shown in FIG. 2, and the currents shared by the coils 2a at the upper and lower ends in the axial direction are twice as much as those by the coils 2b at the middle.

This is because the number of leakage flux linkages of the upper and lower end coils 2a is smaller than the number of leakage flux linkages of the intermediate coil 2b. That is, since the leakage reactance of the winding is proportional to the number of leakage magnetic fluxes, the leakage reactance of the upper and lower end coils 2a is small, and therefore its internal impedance is lower than that of the intermediate coil 2b.
This is because the internal impedance of the

Therefore, the current shared by the upper and lower end coils 2a reaches twice that of the intermediate coil 2b, and heat proportional to the square of this current is generated in each of the upper and lower end coils 2a as abnormal overheating. For this reason, the conductor cross-sectional area of the upper and lower end coils 2a is made larger than that of the intermediate coil 2b. However, this method has the disadvantage that the output winding is large and the manufacturing cost is high.

[Purpose of the invention]

It is an object of the present invention to solve the above-mentioned conventional drawbacks and to provide an inexpensive winding without increasing the size of the output winding.

[Key points of the invention]

In this invention, the electrical conductivity of the conductors of the parallel coils located at both ends in the axial direction of the multi-parallel large current winding is made higher than the electrical conductivity of the intermediate coil conductor. For example, aluminum is used for the middle coil conductor and copper is used for the upper and lower end coil conductors.

[Embodiments of the invention]

FIG. 3 shows an embodiment of the present invention, in which an output winding 31 is arranged concentrically outside the input winding 1. The output winding 31 is formed by stacking a plurality of disc-shaped coils, that is, coils 31a at both upper and lower ends in the axial direction and an intermediate coil 31b located between them, and is connected in parallel to the output bus 3 designated by u and x. . The conductors of the coils 31a at both the upper and lower ends are made of copper, and the conductors of the intermediate coil 31b are made of, for example, aluminum, which has lower conductivity than the conductors of the upper and lower end coils. The radial conductor dimensions of the coils 31a at both the upper and lower ends may be reduced in order to reduce the eddy current loss.

The conductor of output bus 3 is generally connected (welded) to a high current bus.
Aluminum is used because of its workability and weight reduction.

〔Effect of the invention〕

Since this invention uses a conductor with good conductivity for the coil at the end of the winding, the temperature rise at the end of the winding is reduced.
The temperature rise of the entire winding is reduced and made uniform. Further, if the capacity of the cooler is the same as that of the conventional method, it is possible to increase the current density of the winding and increase the temperature rise value to a level higher than that of the conventional method. That is, the weight of the winding can be reduced by the amount of increase in the current density of the winding.

[Brief explanation of the drawing]

Figure 1 is a conventional multi-parallel large current winding arrangement diagram, Figure 2 is a diagram of the 1st
The current distribution diagram of the output winding shown in FIG. 1: input winding, 31: output winding, 31a: coils at both ends in the axial direction, 31b: intermediate coil. 5- Figure 3

Claims (1)

[Claims] 1) In the winding of a transformer where the output winding is arranged concentrically outside the input winding and consists of a plurality of disc-shaped coils arranged one on top of the other in the axial direction, and these coils are connected in parallel to the output bus bar. A multi-parallel high current winding for a transformer, characterized in that the conductivity of the coil conductors located at both ends in the axial direction of the output winding is selected to be higher than the conductivity of other coil conductors of the output winding.