Magnetic earth clamp for overhead line equipment structures

Abstract

An earth clamp for overhead line structures, comprising a clamp frame comprising a profile having a flat contact point at each end of the profile and a middle part at different height than each contact point at each end of the profile, at least one magnetic part arranged to the clamp frame for magnetically attaching the clamp frame against a surface, said magnetic part being situated towards the middle part of the frame profile, wherein the magnetic part is arranged to move in relation to the frame between the level of the contact points and away from the level defined by the contact points towards the middle part, to allow the earth clamp to be attached to a structure facilitating mechanical and electrical connection thereof with the overhead line structure through the magnetic part and the contact points, and comprising means to move the earth clamp frame and / or the magnetic part in relation to the overhead line structure to counteract the magnetic force exerted by the magnetic part to the overhead line structure in order to release the earth clamp from the overhead line structure. A corresponding portable earth is presented.

Description

[0001] MAGNETIC EARTH CLAMP FOR OVERHEAD LINE EQUIPMENT STRUCTURES

[0002] FIELD OF THE INVENTION

[0003] Generally, the present invention relates to electromechanic arrangements for earthing overhead line structures. Particularly, however not exclusively, the invention pertains to a universal portable earth clamp.

[0004] BACKGROUND

[0005] Existing portable earthing solutions for Overhead Line Equipment (OLE) generally require the provision of structure mounted earth attachment points with associated fixings, which is usually in the form of a peg. The existing portable earthing solutions require structure mounted earth attachment points to apply a short portable earth. Such solutions are typically sprung jaw type in design. These solutions have the shortcoming of having to use earth attachment points, which can impact access and cause cancellation of work if earth attachment points are missing or broken since earth attachment points are typically only fitted 400 meters apart from each other. Since the earth attachment points are not provided at all structures this limits the overhead line structures where portable earths can be applied.

[0006] Hence, there is a need for a more universal type earth clamp solution that evades the use of earth attachment points and allows for associated safety, time and cost benefits be realised whilst optimising the time available to undertake work within very constrained railway infrastructure access windows.

[0007] SUMMARY OF THE INVENTION

[0008] The objective of the embodiments of the present invention is to at least alleviate one or more of the aforementioned drawbacks evident in the prior art arrangements. The objective is generally achieved with an arrangement and method in accordance with the claim set.

[0009] The present invention provides an earth clamp especially usable for OLE structures that offer a suitable surface of ferromagnetic material. One ex- ample of an application of the present invention is when a single earth or multiple earths are required at an OLE structure where there are no dedicated or specific earth attachment point pegs for the application of conventional earth clamps. Another example includes a situation where the earth attachment point pegs are damaged or missing preventing the application of conventional short portable earths. Some other applications include where long portable earths have been typically used. Some further applications include where a visible earth is required to be applied at a site of work to an OLE structure.

[0010] Benefits of the present invention comprise providing a short portable earth option that can be used on a number of overhead line structures having a suitable surface of ferromagnetic material without a requirement for earth attachment points to be fitted. Further, the present invention provides an alternative option to the use of long portable earths in certain cases thus offering a direct safety benefit due to the risks associated with long portable earths. Further, the present invention provides a short portable earth option that can be utilised in the case of broken or missing earth attachment points. Further, the present invention enables an optimised approach to earthing and the use of a single additional earth at an overhead line structure. Further, the present invention enables a visible earth to be applied at a site of work to an OLE structure to prove the equipment has been made dead. Further, the present invention is compatible with use of existing live working poles and associated dispensing / retrieval adaptors.

[0011] In accordance with one aspect of the present invention an earth clamp for overhead line structures, comprising:

[0012] - a clamp frame comprising a profile having a flat contact point at each end of the profile and a middle part at different height than each contact point at each end of the profile,

[0013] - at least one magnetic part arranged to the clamp frame for magnetically attaching the clamp frame against a surface, said magnetic part being situated towards the middle part of the frame profile, o wherein the magnetic part is arranged to move in relation to the frame between the level of the contact points and away from the level defined by the contact points towards the middle part, to allow the earth clamp to be attached to a structure facilitating mechanical and electrical connection thereof with the overhead line structure through the magnetic part and the contact points, and o comprising means to move the earth clamp frame and / or the magnetic part in relation to the overhead line structure to counteract the magnetic force exerted by the magnetic part to the overhead line structure in order to release the earth clamp from the overhead line structure.

[0014] In accordance with an embodiment of the present invention the earth clamp comprising mechanical actuation lever for moving the earth clamp frame and / or the magnetic part in a direction away from a structure when the earth clamp is attached to the structure.

[0015] In accordance with an embodiment of the present invention the mechanical actuation lever for moving the earth clamp frame and / or magnetic part at least away from the structure when the earth clamp is attached to a structure may be used with a dispensing head.

[0016] In accordance with an embodiment of the present invention the clamp frame may comprise a curvilinear profile.

[0017] In accordance with an embodiment of the present invention the earth clamp comprises a spring connected with the magnetic part to facilitate counterforce to the magnetic part and moving the magnetic part away from the level of the contact points.

[0018] In accordance with an embodiment of the present invention the earth clamp wherein connection between the magnet and the spring assembly is electrically insulated from the clamp frame.

[0019] In accordance with an embodiment of the present invention the magnetic part is electrically bonded to the clamp frame via a flexible braid connection.

[0020] In accordance with an embodiment of the present invention the earth clamp frame the earth clamp frame incorporates guides that aid correct positioning and application of the earth clamp frame. In accordance with an embodiment of the present invention the earth clamp comprises a permanently attached protective cover applied over the magnet that allows safe handling and storage when not in use.

[0021] In accordance with an embodiment of the present invention the earth clamp comprises a removable cover for the magnetic part.

[0022] In accordance with an aspect of the present invention a portable earth arrangement comprising the earth clamp arrangement of claim 1 and a line end connected thereto.

[0023] As briefly reviewed hereinbefore, the utility of the different aspects of the present invention arises from a plurality of issues depending on each particular embodiment.

[0024] The expression “a number of’ may herein refer to any positive integer starting from one (1). The expression “a plurality of’ may refer to any positive integer starting from two (2), respectively.

[0025] Different embodiments of the present invention are also disclosed in the attached dependent claims.

[0026] BRIEF DESCRIPTION OF THE RELATED DRAWINGS

[0027] Next, some exemplary embodiments of the present invention are reviewed more closely with reference to the attached drawings, wherein

[0028] Fig. 1 illustrates a front view of an embodiment of the earth clamp,

[0029] Fig. 2 illustrates a rear view of an embodiment of the earth clamp,

[0030] Fig. 3 illustrates a side view of an embodiment of the earth clamp,

[0031] Fig. 4 illustrates an isometric view of an embodiment of the earth clamp,

[0032] Fig. 5 illustrates a view wherein an embodiment of the earth clamp is attached to an overhead line structure,

[0033] Fig. 6 illustrates a view wherein an embodiment of the earth clamp is attached to an overhead line structure,

[0034] Fig. 7 illustrates a general view of the earth clamp in use, Fig. 8 illustrates a general view of another embodiment of the earth clamp, and

[0035] Fig. 9 illustrates another general view of another embodiment of the earth clamp.

[0036] DETAILED DESCRIPTION OF THE EMBODIMENTS

[0037] Figures 1-4 illustrate main aspects of the earth clamp.

[0038] The earth clamp in accordance with the illustrated embodiment comprises the following features.

[0039] (1) Retrieval bracket

[0040] (2) Release mechanism arm

[0041] (3) Release mechanism hinge point

[0042] (4) Guide

[0043] (5) Release mechanism roller

[0044] (6) Magnet

[0045] (7 A) Clamp frame front contact point

[0046] (7B) Clamp frame rear contact point

[0047] (8) Earth cable connection terminal

[0048] (9) Application lug

[0049] (10) Insulation

[0050] (11) Spring

[0051] (12) Connection bolt

[0052] (13) Magnet cap stow cup

[0053] (14) Earth cable

[0054] The earth clamp comprises at least a clamp frame comprising a curvilinear profile, having a flat contact point (7 A, 7B) or pad at each end of the profile and a middle part at different height than each contact point (7 A, 7B) at each end of the profile. The contact points (7 A, 7B) are fixed and form the horizontal plane or level, which may connect with an OLE structure. The curvilinear profile of the clamp frame may comprise a continuous profile with rounded edges between the middle part and the contact points (7 A, 7B), as illustrated, or the clamp frame profile may comprise a profile with sharp edges between the middle part and the contact points (7 A, 7B), for example wherein a horizontal middle part and horizontal contact points (7 A, 7B) have a vertical or angled areas therebetween with sharp comers dividing the different areas yielding e.g. a “top-hat shape” or the like.

[0055] The earth clamp further comprises at least one magnetic part, such as a magnet (6) or a plurality of magnets (6), arranged to the clamp frame for magnetically attaching the frame against a surface, said magnetic part being situated towards the middle of the frame profile. The magnet (6) is arranged to move in relation to the frame between the level of the contact points (7 A, 7B) and above the level defined by the contact points (7 A, 7B), as illustrated in Fig. 1 and 2 wherein the touching surface of the magnet (6) can be clearly seen to be moved above in relation to the level of the contact points (7 A, 7B), i.e. away from the level defined by the contact points (7 A, 7B), which is also the horizontal level or plane at which the magnetic part connects with the OLE structure, and towards the level of the middle of the clamp frame, to allow the earth clamp to be attached to a structure facilitating mechanical and electrical connection thereof with the overhead line structure through the magnetic part and the contact points. I.e. the magnet (6) is arranged to move “inside” the earth clamp profile, such as in a vertical direction via a spring connection (11) at the middle part of the clamp frame. The earth clamp also comprises means, such as a mechanical actuation lever formed by a retrieval bracket (1), release mechanism arm (2), a release mechanism hinge point (3) and release mechanism roller (5), to move, such as by lever actuation or simply pulling the earth clamp away from a structure, at least the clamp frame in relation to the overhead line structure to counteract and overcome the magnetic force exerted by the magnet (6) to the overhead line structure in order to release the earth clamp from the overhead line structure. For example, as illustrated in Figs. 1-6 the earth clamp comprises a retrieval bracket (1), release mechanism arm (2), a release mechanism hinge point (3) and release mechanism roller (5) wherein by operation of the retrieval bracket (1) the release mechanism roller (5) may be pressed against the OLE structure to which the earth clamp is connected and via the release mechanism arm (2) and release mechanism hinge point (3) a mechanical force can be exerted to move the earth clamp frame in relation to the overhead line structure and to release the earth clamp from the OLE structure. Alternatively, the earth clamp may comprise another type of mechanism to move the earth clamp in relation to the OLE structure, such as a retrieval bracket (1) connected directly to the earth clamp frame, as illustrated in the embodiment of Figs. 8 and 9, so that the earth clamp may be pulled away from an OLE structure by pulling the retrieval bracket (1). Alternatively or additionally, the earth clamp may comprise means to move the magnet (6) at least away from the level of the contact points (7 A, 7B). The magnet (6) may be connected with a spring (11) via insulation (10) at the frame to help counteract the magnetic force exerted by the magnet (6) and move the magnet at least away from the level of the contact points (7 A, 7B) when the earth clamp is not connected to a structure. This way the magnet (6) may move against and attach to a ferromagnetic structure on level with the contact points (7 A, 7B) attaching the earth clamp to the structure, and the earth clamp frame and / or the magnet (6) may also be moved away from connection by operation of the bracket (1) counteracting the magnetic force exerted to a structure and hence detaching the earth clamp from the structure. A protective cover, such as a magnet cap stow cup (13), may be used over the magnet that allows safe handling and storage when not in use. The protective cover may be permanently fixed or removable. The insulation (10) is used to electrically insulate the magnet and the spring assembly from the clamp frame. As illustrated, the magnet (6) may be electrically bonded to the clamp frame via a flexible braid connection.

[0056] The earth clamp may further comprise guides (4) for easier operation and attachment of the earth clamp to an OLE structure. Such guides (4) are beneficial since the earth clamp is operated by a live working pole from a distance away and at height. Further, the earth clamp may comprise an application lug (9) or similar structure for hoisting the earth clamp with a live working pole at height.

[0057] The earth clamp further comprises an earth cable connection terminal (8) connected via an earth cable (14) to the magnet (6) for connecting the earth clamp with a line end.

[0058] Although not illustrated the earth clamp may comprise a housing or a removable cover

[0059] The earth clamp further comprises a connection means for connecting a line end with a line to the earth clamp. The earth clamp is particularly suitable railway applications and related environments including on 25 kV AC, 12 kA rated systems.

[0060] Figures 5-6 illustrate the earth clamp attached to an OLE. Therein the earth clamp is shown to be attached to flat surface of ferromagnetic material. The earth clamp is shown to be connected to a line end, which may comprise a conventional line end clamp operable at height by a live working pole the earth clamp and line end essentially constituting a portable earth. As illustrated, the live part is separated by the insulator from the rest of the OLE structure such as the mast to which the earth clamp may be connected. The cable connection between the line end clamp and the earth clamp may be kept substantially short.

[0061] Figure 7 illustrates an example setting of the earth clamp in use. In this application an overhead line equipment structure for railways is shown for which the operator uses the earth clamp. The operator may use a conventional live working pole with suitable dispensing and retrieval adaptors, such as a dispensing head or other operating sockets, to attach and detach the earth clamp at height and at a preferred location having a surface of ferromagnetic material. The operation is convenient since placing the earth clamp at a certain part is simple since only a sufficiently flat ferromagnetic surface is needed. Due to the magnetic force the earth clamp attaches automatically to a ferromagnetic surface and removal is also simple since the magnetic force can be easily counteracted via the mechanical actuation lever, which the operator can operate with the live working pole. As can be seen from the figure 7 the earth clamp provides for a visible earth which can be applied at a site of work to prove the overhead line equipment has been made dead. Since the earth clamp may be attached on any substantially flat ferromagnetic surface the earthing can be done at height avoiding the need for a long portable earth.

[0062] The scope of the invention is determined by the attached claims together with the equivalents thereof. The skilled persons will again appreciate the fact that the disclosed embodiments were constructed for illustrative purposes only, and the innovative fulcrum reviewed herein will cover further embodiments, embodiment combinations, variations and equivalents that better suit each particular use case of the invention.

Claims

Claims1. An earth clamp for overhead line structures, comprising- a clamp frame comprising a profile having a flat contact point at each end of the profile and a middle part at different height than each contact point at each end of the profile,- at least one magnetic part arranged to the clamp frame for magnetically attaching the clamp frame against a surface, said magnetic part being situated towards the middle part of the frame profile, o wherein the magnetic part is arranged to move in relation to the frame between the level of the contact points and away from the level defined by the contact points towards the middle part, to allow the earth clamp to be attached to a structure facilitating mechanical and electrical connection thereof with the overhead line structure through the magnetic part and the contact points, and o comprising means to move the earth clamp frame and / or the magnetic part in relation to the overhead line structure to counteract the magnetic force exerted by the magnetic part to the overhead line structure in order to release the earth clamp from the overhead line structure.

2. The arrangement of claim 1 wherein the earth clamp comprising mechanical actuation lever for moving the earth clamp frame and / or the magnetic part in a direction away from a structure when the earth clamp is attached to the structure.

3. The arrangement claim 2 wherein the mechanical actuation lever for moving the earth clamp frame and / or magnetic part at least away from the structure when the earth clamp is attached to a structure may be used with a dispensing head.

4. The arrangement of any preceding claim wherein clamp frame comprising a curvilinear profile.

5. The arrangement of any preceding claim wherein the earth clamp comprises a spring connected with the magnetic part to facilitate counter-force to the magnetic part and moving the magnetic part away from the level of the contact points.

6. The arrangement of any preceding claim wherein the connection between the magnet and the spring assembly is electrically insulated from the clamp frame.

7. The arrangement of any preceding claim wherein the magnetic part is electrically bonded to the clamp frame via a flexible braid connection.

8. The arrangement of any preceding claim wherein the earth clamp frame incorporates guides that aid correct positioning and application of the earth clamp frame.

9. The arrangement of any preceding claim wherein the earth clamp comprises a permanently attached protective cover applied over the magnet that allows safe handling and storage when not in use.

10. The arrangement of any preceding claim wherein the earth clamp comprises a removable cover for the magnetic part.

11. A portable earth comprising the earth clamp arrangement of claim 1 and a line end connected thereto.