GB2109639A

GB2109639A - Support for electrical conductors in inductive apparatus

Info

Publication number: GB2109639A
Application number: GB08227137A
Authority: GB
Inventors: Olle Andersson
Original assignee: FIGEHOLMS BRUK AB
Current assignee: FIGEHOLMS BRUK AB
Priority date: 1981-09-24
Filing date: 1982-09-23
Publication date: 1983-06-02
Also published as: SE8105642L; CA1206579A; DE3233920A1; CH657716A5; GB2109639B; FR2513431B1; FR2513431A1; SE428068B

Abstract

A support is described for one or more electrical conductors (15, 16, 17 and 18) forming part of an electrical apparatus, for example a transformer, which includes at least one inductive winding (10, 11, 12) the conductors (15-18) being arranged externally of the winding(s) of the apparatus. The support comprises at least one channel-section beam (20, 21) which may be made of pressboard, having two spaced-apart flanges (24, 25) interconnected by a web (23) defining therebetween an internal beam space (26) in which the distance between at least part of the inwardly-facing surfaces of the flanges (24, 25) decreases in the direction from the web (23) towards the opening (27). At least one block (28) is disposed within the beam space (26) and has opposed surfaces (29, 30) confronting said parts of the inwardly-facing surfaces of the beam flanges (24, 25) the or each block (28) being displaceable and able to be locked to the beam (20, 21) in an arbitrary position in the longitudinal direction of the beam, by a respective bolt (32) in screw- threaded engagement with a hole (31) in the block. The bolt(s) (32) also serve to clamp the conductors (15-18) against the free ends of the flanges (24, 25) between, for example, ribs (22). <IMAGE>

Description

SPECIFICATION Support for electrical conductors Technical field This invention relates to a support of the kind employed for supporting at least one electrical conductor forming part of an electrical apparatus which includes at least one inductive winding, for example a transformer or reactor, said at least one conductor being arranged externally of said winding.

During assembly of transformers and reactors, conductors between windings and tap changers, conductors between windings and electricallyinsulated bushings and conductors disposed outside a winding and which connect a conductor at one end of the winding to a conductor at the other end of the winding, need to be supported in a reliable manner. This is important, among other things, to prevent damage to the conductors during transportation, when the-transformer or reactor can be subjected to strong vibrations for a considerable period of time, and during operation of the transformer or reactor when short-circuit periods occur. The number of conductors of this kind in a transformer or reactor can be very large, amounting to well over one hundred.

Background art At the present time, supports of the kind referred to are often made of pressboard or wood.

According to current practice, each support is individually designed with regard to its role in a particular apparatus so that, normally, each support can only be used in one type of apparatus and in one particular position in that apparatus.

The present invention aims to provide a support of the kind referred to which eliminates, or at least substantially reduces, the expensive design work involved in the present production of such supports. The support according to the invention, while employing a very limited number of different parts, is useful for supporting conductors in a range of inductive electrical apparatus of different types and sizes because of its great flexibility and adaptability to different supporting tasks. The parts of the support can, with advantage, be held in store for use in a wide range of different supporting operations.

Disclosure of the invention According to the invention, a support of the kind referred to comprises a channel-section beam having two spaced apart flanges interconnected by a web, said flanges and web defining therebetween a space having an opening, between the free edges of said flanges, which is disposed substantially parallel to said web, in which space the distance between at least part of the inwardly-facing surfaces of said flanges decreases in the direction from said web to said opening, at least one block within said space having opposed surfaces confronting said parts of the inwardly-facing surfaces of said flanges, said at least one block being displaceable in said space in the longitudinal direction of said beam, and means associated with said at least one block for locking the latter to said beam in an arbitrary position in the longitudinal direction of said beam.

Preferably, the beam and the block(s) are made of pressboard, which can be impregnated with oil or other electrically-insulating fluid, so that after the impregnation the beam and the block(s) do not contain voids where corona may occur. It is, however, possible to make the beam and the block(s) of an electrically-insulating material other than pressboard, for example wood, provided that it is made certain that there are no voids in the material which are not filled with an electricallyinsulating fluid.

The means for locking the or each block to the beam may take the form of a screw-threaded hole in the block, in which a threaded bolt of electricaliy-insulating material, for example glass fibre-reinforced plastics material, is arranged. The block can then be locked in the beam, either by pulling the block with the bolt against the inwardly-facing, converging surface parts of the flanges of the beam, or by using the bolt to press the block against these converging surface parts of the flanges. In the latter case, the hole in the block is a through-hole and the extremity of the bolt shank which is remote from the head of the bolt presses against the web of the beam.

The or each conductor to be supported may be fixed directly to the block(s) by attachment means arranged on the block(s) or by at least one rib which is anchored to, and extends between, blocks situated in spaces of different beams. In order to hold the conductor(s) in predetermined position(s) in the block(s)- and the rib(s), respectively, said attachment means or rib(s) may be provided with spacing means. The attachment means, the rib(s) and the spacing means may be made from the same material as exemplified above for the beams and block(s).

Brief description of the drawings The invention will now be described in greater detail, by way of example, with reference to the accompanying drawings, wherein: Figure 1 is a schematic side view of an electrical transformer with conductors, located outside the transformer windings, clamped by one embodiment of supports in accordance with the invention, Figures 2 and 3 are perspective views, on an enlarged scale, of a beam and a block, respectively, of one of the supports used in the transformer of Figure 1, Figure 4 is a plan from below, on an enlarged scale, of one of the supports of the transformer of Figure 1, employed to clamp a plurality of conductors, Figure 5a is an end view corresponding to Figure 4, Figure Sb is a view similar to Figure 5a, but showing an alternative way of employing the support, Figure 6 is a view similar to Figure 4, but showing an alternative embodiment of a support in accordance with the invention, Figure 7 is a side view of part of a support in accordance with the invention which comprises a spacer means, Figure 8 is a view similar to Figure 7 relating to part of an alternative embodiment of the support, and Figure 9 is a perspective view, on an enlarged scale, of the spacer means employed in Figures 7 and 8.

Description of preferred embodiments Figure 1 shows an electrical transformer with three windings 10, 11 and 12 mounted on three legs (not shown) of an iron core which extend between an upper yoke 13 and a lower yoke 14 of the core. In each winding (as shown for the windings 10 and 12) a plurality of conductors 1 5 and 1 6, respectively, extend from one end of the winding to the other end thereof, outside the respective winding, so that a first conductor at one end of the winding is connected to a second conductor at the other end, and so on, so that all the conductor turns in the winding are seriesconnected. In the transformer illustrated, all the conductors 1 5 and 1 6 have centre taps which are connected by conductors 1 7 (only shown for the winding 12) to a tap changer (not shown).From the winding 11, conductors 1 8 extend from a tap 1 9 to electrically-insulated bushings (not shown).

In Figure 1, the conductors 15, 16, 17 and 18 are supported by means of vertical beams 20 anchored to the yokes 13 and 14, for example by bolts, by means of horizontal beams 21 anchored to the vertical beams 20, and by means of ribs 22 anchored to the horizontal and vertical beams, respectively.

As shown in Figure 2, each of the beams 20 and 21 is of channel section and has two spacedapart flanges 24, 25 interconnected by a web 23.

The web 23 and the flanges 24, 25 define a space 26 with an opening 27, between the free edges of the flanges 24 and 25, disposed substantially parallel to the web 23. The distance between the inwardly-facing surfaces of the flanges 24 and 25 decreases in the direction from the web 23 to the opening 27. In the embodiment shown in Figure 2, which is an especially preferred embodiment, the cross-section of the beam 20 (21) is trapezoidal. However, the flanges 24 and 25 may have such a shape that the distance between their inwardly-facing surfaces does not decrease between all parts of these surfaces in the direction from the web 23 towards the opening 27. For example, the cross-section of the beam 20 (21) nearest the web 23 may be of rectangular shape, whereas nearest the opening 27 it may be of trapezoidal shape.

A block 28, see Figure 3, is freely displaceable in the longitudinal direction of the beam 20 (21) in the space 26 of the latter. Like the beam, the block 28 has a cross-sectional shape, perpendicular to its direction of movement in the beam, which is of trapezoidal shape. The block 28 has two contact surfaces 29 and 30 which face, and are parallel to, the flanges 24 and 25, respectively, of the beam. The block 28 is provided with a through-hole 31 which is screwthreaded along at least part of its length.

The conductors 15 are anchored to a beam 21 by blocks 28 and ribs 22, as shown in Figures 4 and 5a or in Figure 5b. As will be seen from Figures 4 and 5a, one rib 22 rests against the free ends of the flanges of the beam 21 and the block 28 is anchored to the beam by being pulled against the converging flanges of the beam by a bolt 32, the bolt head 33 of which bears against a second rib 22.

In the alternative embodiment shown in Figure Sb, the block 28 is pressed against the flanges of the beam 21 by screwing the extremity 34 of the bolt 32 right through the block 28, until it presses against the web of the beam. The ribs 22 and the conductors 15 are then held together by a nut 35 arranged on the bolt 32.

Each of the beams 21 is fixed to two beams 20 by bolts passing through the web 23 of the beam 21 and down into blocks 28 displaceably mounted in the beams 20. The conductors 16, 17 and 1 8 are anchored to beams and ribs in a manner analogous to that employed for the conductors 15.

From the above description, it will be appreciated that the beams 21 can be arranged not only horizontally at any desired height, but that they can also be disposed at an angle to the horizontal. Furthermore, the ribs 22 can be arranged in any desired position in the longitudinal direction of the beams 21. The possibility of displacing the parts of the conductor supports in a stepless manner into different positions means that a support can always be adapted to the particular supporting problem in question. It is, of course, possible, in an alternative embodiment of the support, to use only the ribs 22 between two beams 20, in which case these ribs, at least at one end, would be anchored to a block 28 in one of the beams.

Preferably, they are anchored in this manner at both ends in the two beams 20.

Figure 6 shows an alternative embodiment of the support in accordance with the invention, in which a conductor 1 5 (or a small number of such conductors) is anchored to the blocks 28 by two plates 36, one of which rests against the free ends of the flanges of the beam 20 (21) and the other of which is disposed on the side of the conductor(s) 15 remote from the beam 20 (21).

As shown in Figures 7 and 8, it is suitable to arrange spacer elements 37 between plates 36 or between ribs 22, these spacer elements being designed to hold the conductor(s) 1 5 in predetermined position(s? between the plates and the ribs, respectively. An example of such a spacer element is shown in Figure 9.

In the above-described examples, the beams 20 and 21 , the blocks 28, the ribs 22, the plates 36 and the spacer elements 37 may all be made of pressboard, which is impregnated with oil or other electrically-insulating liquid. The bolts 32 may be made of glass fibre-reinforced plastics material.

Claims

1. A support for at least one electrical conductor forming part of an electrical apparatus which includes at least one inductive winding, said at least one conductor being arranged externally of said at least one winding, said support comprising a channel-section beam having two spaced-apart flanges interconnected by a web, said flanges and web defining therebetween a space having an opening, between the free edges of said flanges, which is disposed substantially parallel to said web, in which space the distance between at least part of the inwardly-facing surfaces of said flanges decreases in the direction from said web towards said opening, at least one block within said space having opposed surfaces confronting said parts of the inwardly facing surfaces of said flanges, said at least one block being displaceable in said space in the longitudinal direction of said beam, and means associated with said at least one block for locking the latter to said beam in an arbitrary position in the longitudinal direction of said beam.

2. A support according to claim 1, wherein said locking means associated with said at least one block is formed by a screw-threaded hole in said block and a bolt having a head and a screwthreaded shank engaged in said hole.

3. A support according to claim 2, wherein said bolt is arranged to pull said at least one block towards said flanges, said bolt head taking support against said free edges of said flanges.

4. A support according to claim 2, wherein said bolt is arranged to press said at least one block against said flanges, said screw-threaded hole passing right through said block and the end of said shank remote from the head of the bolt pressing against said web.

5. A support according to any of the preceding claims, wherein said at least one block is provided with attachment means comprising plates between said at least one conductor may be held and anchored to said block.

6. A support according to claim 5, wherein spacer means is provided between said plates for holding said at least one conductor in a predetermined position.

7. A support according to any of claims 1 to 4, comprising two of said beams in spaced-apart, substantially parallel relationship and a respective block in said space of each beam, and two substantially parallel ribs extending between said blocks and connected thereto between which said at least one conductor may be anchored.

8. A support according to claim 7, wherein spacer means is provided between said ribs for holding said at least one conductor in a predetermined position.

9. A support according to claim 1, constructed and arranged substantially as herein described with reference to, and as illustrated in, Figures 1--5a, or Figures 1-4 as modified by Figure Sb, Figure 7, Figures 7 and 9 or Figures 8 and 9 of the accompanying drawings.

1 0. An electrical apparatus comprising at least one inductive winding and at least one conductor arranged externally of said at least one winding, wherein said at least one conductor is anchored to the apparatus by a support according to any of claims 1 to 8.

11. Apparatus according to claim 10, wherein the beam or beams of said support is or are secured to an iron core of the apparatus.

1 2. An electrical apparatus constructed and arranged substantially as herein described with reference to, and as illustrated in, Figures 1-Sa, or Figures 1 4 as modified by Figure Sb, Figure 6, Figures 7 and 9 or Figures 8 and 9 of the accompanying drawings.