AU2018100069A4

AU2018100069A4 - Switch Actuator for Pole Mounted Switchgear

Info

Publication number: AU2018100069A4
Application number: AU2018100069A
Authority: AU
Inventors: Mahesh Mukundan; Maxim Samarski; Joni Tortian
Original assignee: NOJA POWER SWITCHGEAR Pty Ltd
Current assignee: NOJA POWER SWITCHGEAR Pty Ltd
Priority date: 2017-12-22
Filing date: 2018-01-16
Publication date: 2018-02-15
Anticipated expiration: 2026-01-16

Abstract

Abstract A switch actuator for operation of pole-mounted switchgear, comprising: a first rotary member for coupling to a switch operating mechanism; a second rotary member for mounting to an upright supporting the switch in a remote position; a flexible elongate member extending between the first rotary member and the second rotary member for conveying drive therebetween, whereby rotation of the second rotary member can operate the switch remotely. 100 - 120"

Description

SWITCH ACTUATOR FOR POLE MOUNTED SWITCHGEAR TECHNICAL FIELD

The present invention relates to actuator arrangements for electrical switchgear, particularly although not exclusively to remote actuators for pole mounted electrical circuit interrupters, isolating switches or combinations thereof.

BACKGROUND

Electrical switchgear must sometimes be operated, whether manually or by a motorized mechanism, from a position which is spaced from the switch or from a housing containing the switch. In one example, pole-mounted switchgear is typically operated by a mechanical transmission arrangement that couples the switch to either a motor or manual operating lever spaced below on the pole. The remote operating point can be either towards ground level for direct operation by a linesman, or at an elevated position intermediate the ground and the switch for operation by an insulated hook stick.

In US Pat. No. 3,668,341 to Smedley for example, a pole-mounted isolator switch is remotely actuated by a manual lever that is coupled to the switch by an elongate rod (64), via a linkage including a pivoting lever arm (42). In this mechanism, the rod reciprocates along its longitudinal axis. Where there is a threshold resting force, an elongate pole is at risk of lateral distortion by bowing

In a pole mounted, gas insulated load break switch manufactured by Shinsung Industrial Electric of South Korea, a rigid elongate pipe or pole is coupled to a manual operating handle at its lower end by a simple angle bracket, and to the switch at its upper end by a bevel gear set. In use, the pipe/pole is rotated about is longitudinal axis, and thus subject to twisting distortion. A pole-mounted air break switch assembly 10 for a three (3) phase circuit is illustrated in FIGs 1A and 1B. Individual switches 12A, 12B, 12C are mounted together on a pole 20 by a supporting cross-arm 22 and linked for common operation by an elongate rotatable bar 14. The operating bar 14 is linked by lever 16 to an upper end of an elongate operating rod 18 A lower end of the operating rod is mounted to the pole 20 by a bracket 24, and further includes a handle member 26 for moving the operating rod along its longitudinal axis. In use, handle member is moved to turn lever 16 and thus turn the rotatable bar 14 in a desired direction to either open or close the switches 12 in unison. Example dimensions of pole-mounted switch gear installation are shown in the drawings, wherein the switch is mounted on the pole 20 at a position approximately 10m above ground level 30, whereas the operating handle is mounted on bracket 24 that is positioned approximately 1.2m from the ground.

Where a single pipe or rod connection is employed in existing actuators, there is a theoretical limit of 180° on the rotation that can be applied to a switch. In practice, the rotation is much less, typically of the order of 90° or less. In some switchgear, for example the Applicants combined load break and isolating switch combination, it is desirable to provide for an expanded range of rotation required for sequential opening and closing of such combination switches. See for example the operating mechanism described in Applicant’s AU Patent Application No. 2016200621.

Furthermore, if constant torque is applied to the handles of conventional operating mechanisms, the force transferred by the interconnecting rod or pipe can vary depending on the position of the handle. This may be due in part to lateral bowing or bending (in translational applications) or twisting (in rotational applications) of known rigid rod or pipe operators. In translational applications, where the rod is being pushed or pulled vertically, there are also significant variations in force that are a function of handle position, i.e. where the operating handle is at a horizontal position, the force in the rod is at a minimum. If the operating handle is close to a vertical position, the force in the rod is larger (if comparing with a desired constant torque).

Any references to methods, apparatus or documents of the prior art are not to be taken as constituting any evidence or admission that they formed, or form part of the common general knowledge.

It is an object of the present invention to provide a switch actuator that addresses the problems of the prior art or at least provides the public with a useful choice.

It is an alternative object of the present invention to provide a mechanical transmission for use in a switch actuator that is inexpensive, compact and light weight and/or provide lowered operating inertia at spaced locations, when compared with transmissions of the prior art.

SUMMARY OF THE INVENTION

According to a first aspect of the present invention there is provided a switch actuator for operation of pole-mounted switchgear, comprising: a first rotary member for coupling to a switch operating mechanism; a second rotary member for mounting to an upright supporting the switch in a remote position; a flexible elongate member extending between the first rotary member and the second rotary member for conveying drive therebetween, whereby rotation of the second rotary member can operate the switch remotely.

The first and second rotary members preferably comprise a pair of wheels each including a peripheral portion for receiving at least a portion of the elongate member therearound. The wheels are suitably selected from the group including a pulley, a toothed wheel and a chain wheel.

In preference, the elongate member is fixed such as by a clamp, to or at least positively engaged with a wheel, suitably by at least one peripheral location.

Preferably, the elongate member comprises a tendon. Suitably the tendon is selected from the group including a cable, a V-belt and a toothed belt. If required, the tendon may include to tendon portions, each portion providing for separate attachment to a rotary member.

Most suitably, the tendon comprises a twisted, multi-strand cable composed of a metallic or similarly durable material and the first and second rotary members each comprise a pulley wheel with which the cable is engaged.

In an alternative form, the elongate member may comprise at least in part a plurality of links, suitably comprising an endless chain.

The switch actuator may further comprise: a first attachment for rotational mounting of the first rotary member directly to, or at least adjacent to, the switch operating mechanism, for example on a switch housing or a switch support; and/or a second attachment for rotational mounting of the second rotary member on the switch support upright at the remote position.

In another aspect, the invention resides in an electrical switchgear assembly including a switch for mounting in an elevated position on a support upright and having a remotely operated mechanism including the switch actuator as set out above.

In a further aspect, the invention resides in an electrical switchgear installation including the above-described switchgear assembly.

Suitably, the upright may comprise a timber pole, a steel tower or a steel and concrete composite or “Stobie” pole.

In a still further aspect, the invention resides in a kit of parts for retro-fitting a remote actuator to an item of switchgear, the kit comprising: the switch actuator as set out above; a first attachment for rotational mounting of the first rotary member directly to, or at least adjacent to, the switch operating mechanism; and a second attachment for rotational mounting of the second rotary member on the switch support upright.

In yet another form, the invention resides in a mechanical transmission for actuating switchgear, comprising: a first pulley for coupling to a switch operating mechanism, the first pulley including opposed flanges retained in spaced relation and spanned by a first polar array of transverse pins; a second pulley for mounting at a location remote from the switch operating mechanism, the second pulley including opposed flanges retained in spaced relation and spanned by a second polar array of transverse pins; and a twisted, multiple strand cable extending between the first pulley and the second pulley, wherein the cable is selected in order to assume a piecewise linear engagement with outer surfaces of the transverse pins where said cable engages with each pulley.

Suitably, a diameter and strand arrangement of the cable is selected in relation to a diameter of the pulleys and number of pins in each transverse array so as not to exceed a desired minimum bending radius of the cable, in use.

BRIEF DESCRIPTION OF THE DRAWINGS

Preferred features, embodiments and variations of the invention may be discerned from the following Detailed Description which provides sufficient information for those skilled in the art to perform the invention. The Detailed Description is not to be regarded as limiting the scope of the preceding Summary of the Invention in any way. The Detailed Description will make reference to a number of drawings as follows:

Figure 1A is a fragmentary side view of a PRIOR ART pole-mounted electric disconnecting switch installation;

Figure 1B is a fragmentary front view of the PRIOR ART pole-mounted electric disconnecting switch installation of FIG. 1A;

Figure 2 is a front view of a switchgear installation 100 including a switch actuator 150 of a preferred embodiment of the present invention;

Figure 3 is a side view of the switchgear installation of Figure 2;

Figure 4 is a partial rear view of the switchgear installation of Figure 2;

Figure 5 is an enlarged fragmentary rear isometric view of the switch actuator illustrated in Figure 2; and

Figure 6 is an enlarged fragmentary front isometric view of the switch actuator illustrated in Figure 2.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS

Referring now to Figures 2 and 3, there is depicted an upright elongate member here in the form of a wooden pole 50 upon which an electrical switch 60 is installed at a position elevated from ground level. The switch includes a housing 62 which is supporting by a mounting arm 52 extending outwardly from the pole 50 from bracket 54 as best seen in Fig. 3. The switch further includes an internal operating mechanism (not visible) having an input shaft with rotatable spigot end 64 protruding from one end of the housing 62 that is here adjacent to the pole 50.

The switch actuator 100 of the present embodiment includes a first rotary member, here in the form of a pulley 110, coupled directly to switch operating spigot 64. The switch actuator 100 also includes a second rotary member, also in the form of a pulley 120 in the present embodiment, that is mounted on the pole 50 at a position remote from the switch 60, and suitably closer to ground level for convenient access by an authorized operator. The second pulley 120 is freely rotatable on a bearing 122 held by pole bracket 56 provided at the remote operating position. Although the first and second pulleys are illustrated in alignment with one another, an advantage of the actuator is tolerance for misalignment, as discussed further below.

The switch actuator further includes a flexible elongate member, here in the form of a tendon that is substantially inextensible. The tendon of the embodiment is suitably comprised of a twisted, multi-strand cable 130 of metallic (e.g. steel) or other relatively flexible and durable material. The cable of the embodiment is suitably in a single length, having a lead portion 130L and a return portion 130R, and fixed to each of the first and second pulleys 110, 120 in at least one, desirably peripheral, location by a clamp and/or a loop (not shown). The cable 130 interconnects the first and second pulleys, suitably conveying drive input at the second pulley 120 to the first pulley 110 for operating the switch 60 via operating mechanism input shaft spigot 64. In Fig. 4, the pole has been omitted from this drawing such that the lead 130L and return 130R portions of the interconnecting cable 130 are more clearly visible.

Enlarged views of arrangements in the actuator 100 associated the first pulley 110 and the second pulley 120 are shown in Figures 5 and 6 respectively. Figure 5 shows a reverse face of a bracket 114 that carries a first pair of guide rollers or sheaves 116L, 116R which guide the (in use upper) lead 130L and return 130R portions of interconnecting cable 130 to and from the first pulley 110. The first pulley is fixed to an end face of the switch operating spigot 64 by a plurality of retainers, here in the form of hex head type bolts 118. A polar array of pins, here in the form of bolts 117, is also provided so as to retain in spaced relation and span opposed wheel flanges 111. The array is arranged adjacent an outer periphery of the first pulley 110. In use, the cable 130 rides on the outer surfaces of the transverse pins in a substantially piece-wise linear curved fashion. This pulley arrangement, wherein the cable is subject to local bending across the transverse pins, is expected to provide a gripping action, for positive torque transfer between the longitudinally moving cable and the rotating pulley. Furthermore, selection of a relatively smaller cable required in order to achieve an appropriate bending radius will be lighter and thus allow rapid switch actuation through reduced inertia. One or more individual bolts 117 of the bolt array may conveniently be employed for anchoring a clamp (not shown) for fixing the cable 130 to the first pulley. An additional bolt (not shown) or machined part may also be used to anchor a clamp to fix the cable 130 to the first pulley 110.

Turning to Figure 6, there is shown rotationally mounted on the bracket 56, a second pair of guide rollers or sheaves 126L, 126R which similarly guide (in use lower portions of) the lead 130L and return 130R portions of interconnection cable 130 relative to and from the second pulley 120. The second pulley 120 of the present embodiment includes opposed flange members 121 spanned by a polar array of pins in the form of bolts 127 that inter-engage with the cable 130 in the manner described above in relation to the first pulley 110. The free ends of the cable portions 130L, 130R are each clamped to the pulley by a clamping arrangement (not shown). The second pulley 120 is attached to a bearing (not shown) for rotation relative to the bracket 56 by way of an array of fixing members 128. Within the array of fixing members 128, there is provided an array of apertures 125 for attachment of either a manual drive lever (not shown) or a motorised drive. Fixing members 128 provide the attachment of the pulley 120 to a bearing housing (not shown). Fixing apertures 125 are used for attachment to either a manual drive lever or motorised drive

In a variation to the above described bracket 56, the rotational mount (not shown) for the second pulley 120 may be (in use) vertically adjustable in order to set a desired tension in the interconnecting cable 130. The adjustable mount may further include a dynamic tensioning arrangement, using a resilient member such as a coil spring, to allow for thermal expansion of the tendon. Suitably the dynamic tensioner would include a temporary lock-out to facilitate positive drive when in use. The horizontal spacing of the guide rollers or sheaves 126 may also be adjustable to similar end, if required. In a further variation, the cable may be provided in separate sections, which sections are each independently attached to respective first and second rollers.

In terms of installation and with reference to Figures 3 and 4, a length of cable 130 is looped over the first or upper pulley 110 and ends of each of the leading and return portions of the cable secured to the second or lower pulley 120, using clamps to apply a predetermined tension to each portion. The tensions may be different to allow for the different mechanical operation of switch opening and closing actions. For example in a dual action switch, a load break switch is first operated followed by a visual break isolator during opening, and the sequence is typically reversed upon closing the dual action switch. It should also be appreciated that, in the present embodiment, the mounting positions of the respective guide rollers pairs, 116, 126 bring the substantially linear paths of the cable runs within a lateral profile of the pole 50. If required, a protective cover may be provided on the pole over the path of the cable 130 to avoid interference by flying debris, such as might be present in a storm. Locking means may also be provided on the lower, second pulley to prevent unauthorized switch operation, optionally employing an enclosure or cabinet.

In use after installation, a manual handle can be attached via apertures 125 to the lower, second pulley 120 near to ground level and (for example) turned in an anticlockwise direction to open an already closed switch. Alternatively, the second pulley 120 could be turned in a clockwise direction to close an open switch - in each case the first pulley 110 coupled to the switch operating spigot 64 being driven accordingly by interconnecting cable 130. Note that the opposed arrangement of first and second pulleys in the illustrated embodiment results in a notional reversal of the rotation applied to the switch operating mechanism from the point of view of the operator.

It will be appreciated that, in other embodiments of the invention, the first rotary member may coupled to the switch operating mechanism by an intermediate compact transmission, such as a gear set. Similar considerations apply to the second rotary member, particular where motive power is provided by a rotary drive such as a motor. Although the pulleys are paired in the present embodiment, different sized pulleys may be specified to achieve a desired gearing ratio.

In other embodiments, the pulleys may include a periphery having V-cross-section for cooperation with a tendon in the form of a fibre reinforced V-belt, or the pulleys may include toothed peripheral portions for cooperation with a tendon in the form of a toothed belt. Similarly, the flexible elongate member in other embodiments may be comprised, at least in part, of a plurality of links which may take the form of a chain wherein the first and second rotary members may include chain wheels.

The preferred embodiments of the invention deliver a number of potential advantages, including that a constant torque applied to the cable at the second pulley 120, the force delivered by the cable 130 to the second pulley 110 at the switch is also substantially constant. The arrangement of pulleys 110, 120 and interconnecting cable 130 is capable of providing greater than 180° of rotation at the switch operating mechanism. A further advantage of the actuator is that use of a flexible interconnecting tendon or multi-link interconnection allows a significant degree of misalignment between the pulleys, in terms of lateral or horizontal mismatch (or a combination of these dimensions), e.g. when mounted on a curved surface, allowing relative translation around the arcuate curve where necessary A number of further optional solutions allowing a larger degree of misalignment, such as pilot rollers for the cable mounted at appropriate positions intermediate the first and second pulleys or Bowden type sheathed cable sections, may also be employed.

When the switch actuator of the embodiment is supplied as a kit of parts, the compact nature of a flexible tendon or multi-link interconnection allows for more cost-effective transport and storage, compared particularly with rigid, elongate pipes or rods.

It will be appreciated that, although the actuator of the embodiment has been described in relation to pole-mounted switchgear, it will find application in other applications requiring remote operation of switches.

In compliance with the statute, the invention has been described in language more or less specific to structural features or methodical steps. The term “comprises” and its variations, such as “comprising” and “comprised of” is used throughout in an inclusive sense and not to the exclusion of any additional features or steps.

It is to be understood that the invention is not limited to specific features or steps shown or described since the means herein described comprises preferred forms of putting the invention into effect. The invention is, therefore, claimed in any of its forms or modifications within the proper scope of the appended claims appropriately interpreted by those skilled in the art.

Claims

The claims defining the invention are as follows:

1. A switch actuator for operation of pole-mounted switchgear, comprising: a first rotary member for coupling to a switch operating mechanism; a second rotary member for mounting to an upright supporting the switch in a remote position; a flexible elongate member extending between the first rotary member and the second rotary member for conveying drive therebetween, whereby rotation of the second rotary member can operate the switch remotely.
2. A switch actuator according to claim 1, wherein the first and second rotary members preferably comprise a pair of wheels each including a peripheral portion for receiving at least a portion of the elongate member therearound.
3. A switch actuator according to claim 2, wherein the wheels are suitably selected from the group including a pulley, a toothed wheel and a chain wheel.
4. A switch actuator according to any one of the preceding claims, wherein the elongate member is engaged with a wheel at at least one peripheral location.
5. A switch actuator according to any one of the preceding claims, wherein the elongate member comprises a tendon.
6. A switch actuator according to claim 5, wherein the tendon is selected from the group including a cable, a V-belt and a toothed belt.
7. A switch actuator according to claim 5 or claim 6, wherein the tendon includes two tendon portions, each portion providing for separate attachment to a rotary member.
8. A switch actuator according to any one of claims 5 to 7, wherein the tendon comprises a twisted, multi-strand cable composed of a metallic or similarly durable material and the first and second rotary members each comprise a pulley wheel with which the cable is engaged.
9. A switch actuator according to any one of claims 1 to 4, wherein the elongate member comprises, at least in part, a plurality of links, suitably comprising an endless chain.
10. A switch actuator according to any one of the preceding claims, further comprising: a first attachment for rotational mounting of the first rotary member directly to, or at least adjacent to, the switch operating mechanism, for example on a switch housing or a switch support; and/or a second attachment for rotational mounting of the second rotary member on the switch support upright at the remote position.
11. An electrical switchgear assembly including a switch for mounting in an elevated position on a support upright and having a remotely operated mechanism including a switch actuator according to any one of the preceding claims.
12. An electrical switchgear installation including the switchgear assembly of claim 11.
13. A kit of parts for retro-fitting a remote actuator to an item of switchgear, the kit comprising: a switch actuator according to any one of claims 1 to 10; a first attachment for rotational mounting of the first rotary member directly to, or at least adjacent to, the switch operating mechanism; and a second attachment for rotational mounting of the second rotary member on the switch support upright.
14. A mechanical transmission for actuating switchgear, comprising: a first pulley for coupling to a switch operating mechanism, the first pulley including opposed flanges retained in spaced relation and spanned by a first polar array of transverse pins; a second pulley for mounting at a location remote from the switch operating mechanism, the second pulley including opposed flanges retained in spaced relation and spanned by a second polar array of transverse pins; and a twisted, multiple strand cable extending between the first pulley and the second pulley, wherein the cable is selected in order to assume a piecewise linear engagement with outer surfaces of the transverse pins where said cable engages with each pulley.
15. A mechanical transmission according to claim 14, wherein a diameter and strand arrangement of said cable is selected in relation to a diameter of the pulleys and number of pins in each transverse array so as not to exceed a desired minimum bending radius of the cable, in use.