DE1180054B - Process for the production of angle rings for transformers and choke coils that slide between two insulating cylinders - Google Patents

Description

Process for the production of insulating cylinders that can be stretched between two insulating cylinders Angular rings for transformers and reactors is known to be involved in a winding structure for transformers that have a have the cooling channel immediately following the winding, the execution of the edge insulation particularly difficult, as different parts meet opposing requirements to have. This applies to most transformer windings of higher voltage, the designed as disc coil windings, as overturned windings or the like are closed. They border on the cooling channels running outside the winding cylindrical insulating barriers. Reach between the cylindrical insulating barriers in the edge area of the winding, angled rings that overlap with the cylinders and have so much play that they are pressed into the winding in the axial direction can slide in.

An exemplary embodiment of such a known arrangement is shown in FIG. 1. Here, 1 denotes the low-voltage winding, 2 its shield ring, 3 denotes the high-voltage main winding, 4 denotes its shield ring, and 5 denotes the radially extended oil channels extending between the individual coils 3. Furthermore, 6 denotes the cooling channels radially adjacent to the HV winding formed by means of strips, 7 denotes the cooling channels axially adjacent to the end face, 8 denotes the insulating barriers radially adjacent to 6, and 11 and 12 denote the oil channels or cylinders adjoining them in turn . In FIG. 11, the angular ring 10 engages, which is wound, for example, from paper and is surrounded on both sides by annular press chipboard disks 9 in the radially extending part.

As is known, there is a very strongly inhomogeneous field in the edge area between the two windings, which is caused by the in FIG. 1 equipotential lines drawn in dashed lines with the potential 10, 20, 30% etc. is characterized. It can now be seen that the free oil area 14 is penetrated by a very strong field, so that the longest free oil section, which is indicated by the arrow 15 , represents the point of greatest stress.

The constant efforts of the designers who design a fringe field insulation try to keep the distance 15 as small as possible, but to use a construction that simply turns out to be. Various approaches have been taken to achieve this, but they always have certain disadvantages. Thus, the embodiment mainly used is according to FIG. 1 primarily disadvantaged by the fact that both the angle ring 10 and the insulating cylinder 8 have diameter tolerances and furthermore the softer cylinders further inside deviate from the round shape, so that the paper angle ring 10 pushes itself further inwards at these circumferential points than provided according to the drawing. This creates an extension of the free oil path 15 which differs from the drawing and which requires an excessive safety allowance, so that the distance between the windings 1 and 3 has to be chosen uneconomically large due to the tolerance deviations described.

A remedy for these tolerance deviations is achieved in a known arrangement in that the angle ring 10 connects directly to the cylinder 8 and is formed from the cylinder 8 in a known manner by outlining. As a result, the in F i g. 1 is halved and a corresponding increase in the insulation strength of the arrangement is achieved, since it is known that the permissible test voltage can be increased as the oil path becomes smaller in the critical area. A disadvantage of the described arrangement with a directly outlined angle ring, in which no tolerances occur, is that the angle ring 10 tears off from the cylindrical part 11 during pressing or during the expansion of the winding that takes place after the drying, so that a gaping gap between 10 and 11 arises through which the free oil path length 15 is even greater than in the case of FIG. 1; a breakdown between the HV and LV windings can thus be initiated with the smaller spacings used between the two windings.

A third known method of insulation design in the edge field uses the arrangement according to FIG. 1 with the following deviation. In the critical area 14 , the insulation of the shield ring 4 is increased so that it rests directly on the cylinder 8. Furthermore, it has already been proposed to additionally overlap the angle ring 10 with the cylinder 11 by sharpening the interlocking end faces so that the channel 6 is not closed during pressing, but also not enlarged and that the tolerance deviations are nevertheless kept as low as possible. A disadvantage of these two known arrangements is again that the cooling is impaired. This is because the cooling oil cannot run in the edge area of the winding, in particular at 14 , but has to be diverted to the outside within the winding through the channels 5 in the edge area or be conducted from the outside.

The embodiments mentioned do not succeed in all of them to realize the following three requirements at the same time: 1. The cooling duct should also run in the peripheral area outside the winding.

2. The angular ring 10 and cylinder 8 should not have any diameter tolerances, ie should not have significant radial differences at local circumferential locations.

3. The angle ring 10 should be able to be displaced axially relative to the cylinder 8 when the winding 3 is pressed (sliding angle ring).

The invention relates to a method for producing angle rings for transformers and choke coils that can slide between two insulating cylinders, in which, according to the invention, further bean-shaped insulating material with overlap on both sides is wound over the inner insulating (support) cylinder to prepare the angle rings, with corresponding ring-like spaces in the The area of the insulating material can be provided for the subsequent change in length of the winding during drying and pressing; then the outer insulating cylinder is wrapped over it and then, after completion of the winding, the protruding ends of the insulating strips of the angular ring cylinders are formed in a known manner by tearing and folding over to the contour of the winding adapted angle rings: The invention is a special manufacturing process for the isolation. Because the angle ring 10 is wound directly onto the cylinder 12 , the tolerances between the two become zero (requirement 2). As is well known, tolerances always occur when a structure with a large diameter is produced in one and a second associated structure in a second production process and local radial differences occur when the two structures are assembled, which can be much larger than the order of magnitude of the cooling channel width 6, especially with ' Diameters for large transformers of more than one meter.

The method of the invention also makes it possible that the angle ring 10 can slide into the pressing of the winding 3 into the straight therefor freed groove (claim 3), and finally it is achieved that the cooling channel always extends in the edge area outside the winding (demand 1).

In addition to the advantages outlined, the method according to the invention results in corresponding FIG. 2 to 3 the further Vbrteil that compared to the previous arrangement according to FIG. 1 is no longer adjacent to the supporting cylinder 12 , which usually consists of hard paper with a high dielectric constant and low electrical strength, especially in the direction of the layers, but rather the paper cylinder B wound on it Gradients occur, the closer the layers are to the winding, a considerable improvement in the insulation strength is achieved. In addition, the oil channel lying between the cylinder and the winding is relieved because of the lower dielectric constant of the paper compared to hard paper.

The following are some examples of those made in accordance with the invention Isolation arrangements described. The designations are the same as at F i g. 1 elected.

F i g. 2 shows the edge insulation on the inside of the HV winding and shows the state before the angular ring 10 was outlined. F i g. 3 shows the state after the angular ring 10 has been outlined. It can be seen that the highly stressed route in FIG. 3 can thereby be made structurally smaller than in FIG. 1 that one chooses the cylinder 8 , which is not used as a support cylinder, to be thinner. In Fig. 1 this is not possible because here 8 is designed as a support cylinder and must therefore be stronger.

With reference to FIG. 2 can be described as an example of the following simple production process: When producing the winding 3 , the supporting cylinder 12 is first brought onto the winding bench; then that part of the cylinder 13 which corresponds to the radial width of the lower bar 16 is wound up over its entire length. The wound insulating cylinder 13 is then cut through at both ends evenly away from the edge and cut away at the two end faces, pulled off and replaced by strips 16 which are applied to the same circumferential locations on which the spacers 5 are also located. Then the cylinder 13 is again completely wound up over the entire width, but then after each two incisions at 11 on both end faces, the wound insulation material is removed at 11. The cylinder 13 is thus divided into three parts, an upper part 10, a middle part 13 and a lower part 10. However, all three parts cannot yet be moved axially because they are wound up tightly and the strips 16 have not yet been removed.

Now so much sheet paper is unwound from the outer cylinder parts 10 that the in F i g. 2 indicated upper strips 16 and can be held about by a tape on the circumference. These temporary supports can also be applied to the lower ledges 16. Then the cylinder 8 is wound up over its entire length, the strips 16 are placed on it and finally the winding 3 is wound on it and the shield ring 4 is attached to the end faces. Now the winding is pressed, tensioned and both the cylinders 12 and 8 are shortened to the correct length.

Only now are the strips 16 removed at the top inside and outside of the cylinder part 10. Then 10 is torn down around the parts 7 and 9 which have been brought onto the screen ring 4; only now is the angle ring 10 completed and can be held and fixed by an upper cover disk. The same procedure is then carried out on the lower side of the winding. After removing the strips 16, the angle rings 10 sit loosely in the annular groove and can be moved axially in this in both directions without the free oil path length of 15 being increased at any point on the circumference.

F i g. 3 shows the winding and in particular the shield ring in FIG final production position after outlining 10.

While in FIG. 2 and 3, the relationships in the edge field within the OS main winding 3 are described, this is done in FIG. 4 for the conditions outside of the HV main winding 3. The same basic concept of the invention described in the main claim is used, only with the difference that this time it is not the cylinder 8 that is the supporting cylinder, but the cylinder that is placed on the winding 3, after the strips 16 are placed on this. Then in the same way - as in the description of FIG. 2 described - the production process provided, only with the difference that the angular ring 10 created by winding, cutting and outlining is not torn outwards, but this time inwards. As a result, the angle ring 10 in FIG. 4 an equally effective barrier for the fringing field outside the HV winding. This is particularly true when a regulating winding 17 is provided outside the HV winding. This can represent the coarse step in a known manner and be wound as a layer winding.

The known design is then applied to the control winding 17 as a further layer a fine stage with intermingled stages provided. Between the trunk winding 3 and the coarse winding 17 now drops almost the entire surge voltage that occurs in the Impact test of the transformer hits the transformer terminal. Therefore must the isolation between 3 and 17 can be carried out in a similar manner as the isolation between 3 and 1.

F i g. 4 shows the conditions prevailing here. At 18 the cylindrical insulation lying under the coarse winding in the edge area designated. The arrows shown indicate the course of the cooling flow. The immediately inside and outside the winding in the axial channels 6 and 6 ' collected cooling oil flows off on the front side through the axial cooling gap; included becomes 19 as the remaining space between the angle rings 10 or 10 'and the annular disks 9 and 9 'formed.

The measures of the invention make it possible to both the radial Main distance between the HV winding 3 and the US winding 1 as well as those to be reduced considerably between the OS main winding 3 and the coarse winding 17; as a result, the cost of the transformer and its losses are reduced decisive.

Claims (2)

Claims: 1. Process for the production of between two insulating cylinders sliding angle rings for transformers and reactors, d a -characterized by, that over the inner insulating (support) cylinder another sheet-like applied Insulating material wound with overlap on both sides to prepare the angle rings is, with corresponding ring-like spaces in the area of the insulating material for the later change in length of the winding during drying and pressing be provided that then the outer insulating cylinder is wound over it and that finally, after completion of the winding, the protruding ends the insulating strips of the angled ring cylinder in a known manner by tearing and turning angular rings adapted to the contour of the winding are formed. 2. The method according to claim 1, characterized in that the on the support cylinder wound sheet-like insulating material wound with such a gradation that the cylinder parts provided for the angle rings are mutual have radial play. Documents considered: French patent specification No. 1225 716.