GB2349509A

GB2349509A - Three-phase electrical disconnector

Info

Publication number: GB2349509A
Application number: GB0008289A
Authority: GB
Inventors: Bjorn Eriksson
Original assignee: JACOBSEN ELEKTRO AS
Current assignee: JACOBSEN ELEKTRO AS
Priority date: 1999-04-29
Filing date: 2000-04-04
Publication date: 2000-11-01
Also published as: NL1011937C2; NL1011937A1; GB0008289D0

Abstract

A three-phase electrical disconnector for high voltages has three vertical insulator columns 19A,B,C . A first insulator column 19C is rotatable through a given angle around its own axis, and carries a contact arm 29 extending radially from the first insulator column 19C . The two other insulator columns 19A,B are each provided with a stationary contact device 20A,B for engagement with the contact arm 29 in the closed position of the disconnector. All the insulator columns (13A, 16A fig.2), 19A,B,C are supported by a rigid frame-work 1, 2, 3, 6, 9, 10 adapted for foundation in the ground. The framework includes a central beam 10 carrying three transverse beams 3, 6, 9 each supporting the three insulator columns 19A,B,C for one phase. A vertical supporting column 1, 2 is provided for the central beam 10 which is attached to the top of the supporting columns 1,2 by disconnectable fastening means (11,12, Fig.2).

Description

THREE-PHASE ELECTRICAL DISCONNECTOR This invention relates to a three-phase electrical disconnector according to the preamble of the accompanying claim 1. For high voltage operation such disconnectors may be of very large dimensions and are subject to strict requirements as to mechanical stability and accuracy. Moreover, it is important that these electrical disconnectors can be assembled and erected in a convenient manner without requiring too much work, this being of particular interest when replacement of old disconnectors is concerned. In such case interruption of the operation of the electrical switching plant in question, should not be of long duration at the same time as safety considerations are also important.

Substantial improvements in the above and other respects are obtained with a disconnector according to this invention, having novel and specific features as set forth in the claims.

In the following description the invention will be explained by way of an illustrative example, as shown in the drawing: Fig. 1 is an end elevation of an electrical three-phase disconnector, and fig. 2 is a side elevation of the disconnector.

Foundations 33 and 34 on the ground 30 are provided for two vertical supporting columns 1 and 2 as shown. The framework structure for a number of insulator columns comprises as a main component a central beam 10 resting on the top of supporting columns 1 and 2. It is essential in this connection that central beam 10 is attached to the column tops by disconnectable fastening means, and as such fastening means conventional bolts are preferred. Accordingly by loosening such bolts as indicated at 11 and 12 in fig. 2, the whole disconnector structure can be lifted off from the foundations with supporting columns 1 and 2, for maintenance or repair as may be required. More important, however, is the situation where in an electrical switching plant one or more old disconnectors are to be replaced by new disconnectors. By employing new disconnectors as described here, the replace ment operation can take place safely in a substantially shorter time than conventional technology makes possible.

Columns 1 and 2 can be in the form of any equivalent type of supporting structure, such as a lattice structure, and in certain cases it may be sufficient to provide only a single, central supporting column for the central beam 10.

As will be understood the central beam 10 defines together with supporting columns 1 and 2 a plane of symmetry with respect to the main structure or components of the complete three-phase disconnector. Central beam 10 carries three transverse beams 3,6 and 9 of smaller dimensions than central beam 10, and each adapted to support three vertical insulator columns for one phase. Thus, fig. 1 shows transverse beam 9 on which two stationary insulator columns 19A and 19B are mounted as well as a rotatable central insulator column 19C being aligned in the plane of symmetry mentioned above, i. e. directly over the central beam 10. This geometrical relationship between the main components is quite important in the disconnector according to the invention.

On top of central insulator column 19C there is mounted a contact arm 29 which in fig. 1 is shown in a position for closed contacts, whereby the opposite ends of contact arm 29 engage contact devices 20A and 20C respectively, on top of insulators 19A and 19B. This basic arrangement of insulator columns with a rotatable central column 19C and the contact operation as explained, is in principle known per se from earlier disconnector designs.

Fig. 2 at 13A and 16A shows insulator columns mounted on transverse beams 3 and 6 respectively in quite a similar way as described with respect to one phase in fig. 1. It is to be noted that for clarity only one insulator column 13A with its contact device on top is shown in Fig. 2, whereas for the other two phases on transverse beams 6 and 9 the contact devices on top of both stationary insulator columns are shown. See contact devices 20A and 20B in Fig. 1.

As will be seen from the drawing the central beam 10 as well as the transverse beams 3,6 and 9 have all a rectangular cross-sectional shape, that may more or less approach a square shape or profile. In addition to having a good strength and rigidity such beam profiles have an important advantage in practice by serving to protect a vital device for the manoeuvring or operation of the disconnector. This, in particular, applies to rotation of the central insulator columns, as represented by column 19C in fig. 1. In fig. 1 there is shown a drive unit 23 usually comprising a motor, for effecting the rotary movement for closing or opening the contact at either end of contact arm 29, by angular movement thereof through a given angle. For transferring the required drive force or torque from unit 23 to each of the central, rotatable insulator columns for each phase, a rod device or the like can be extended through the interior of central beam 10, with a rotary or translatory motion of such rods for transmission to the central insulators along the central beam 10. The operating device for such rotation will then to a large extent be well protected within the closed crosssection of beam 10.

The drawings also show earthing switch rods as indicated at 40 and 50 serving for the important earthing function as is normally required in such disconnectors. More particularly earthing switch rod 40 is generally pivotable around an axis 41 so that the outer free end of rod 40 moves through an arc as indicated at 44 to a vertical position establishing contact in contact device 20A. For such operation of the earthing switch there is shown a drive unit 43 that may be based on a motor or manual operation. A similar earthing switch rod 50 with its drive unit 53 is also shown somewhat schematically in fig. 1. At 55 the arch followed by closing movement of earthing switch rod 50 is indicated. These earthing switches are each associated with and carried by respective transverse beams 3, 6 and 9.

From the above it will be seen that the main framework formed by central beam 10 and transverse beams 3,6 and 9 support all the disconnector components as well as the earthing switch components and can be handled as a complete assembly during installation on supporting beams 1 and 2, whereby simple and conventional bolt joints at 11 and 12 facilitate the installation and also any removal of the whole structure for repair or replacement of components.

Claims

Claims: 1. A three-phase electrical disconnector for high voltages, comprising for each phase three vertical insulator columns of which a first insulator column is rotatable through a given angle around its own axis, and carries a contact arm extending radially from the first insulator column, and the two other insulator columns are each provided with a stationary contact device for engagement with said contact arm in the closed position of the disconnector, all said insulator columns being supported by a rigid framework adapted for foundation in the ground wherein said framework comprises a central beam carrying three transverse beams, each supporting the three insulator columns for one phase, said beams having a closed, rectangular cross-sectional profile, at least one vertical supporting column is provided for said central beam, which is attached to the top of the supporting column (s) by disconnectable fastening means, and said first insulator columns, said central beam and said supporting column (s) are aligned in a common vertical plane.
2. A three-phase electrical disconnector according to claim 1, wherein said fastening means consist substantially of bolt joints.
3. A three-phase electrical disconnector according to claim 1 or claim 2, wherein an operating device for rotating said first insulator columns is partially arranged through the interior of said central beam.
4. A three-phase electrical disconnector according to claims 1,2 or 3, wherein an earthing switch rod is mounted to at least one transverse beam, for angular movement from a rest position along said one transverse beam to a substantially vertical position for earthing contact.
5. A three-phase electrical disconnector substantially as hereinbefore described with reference to and as shown in the accompanying drawings.