GB2113918A - An operating handle for high voltage switch gear - Google Patents

Abstract

An operating handle 13 comprises two ports 61, 62 joined at a pivot 63 and having respective abutments 64, 65 which interact to maintain the ports 61, 62 in alignment when rotation of the handle in a first angular direction is effected. The handle folds at the pivot if rotation in the opposite angular direction is attempted. Engaging means 66 or 67 may engage the shaft of a switch operating mechanism (12, fig. 1, not shown) and removal and reversing of the handle is required for changing of actuating mode. <IMAGE>

Description

1

GB 2 113 918 A 1

SPECIFICATION

High voltage switch gear

This invention relates to high voltage switch equipment, and, in particular, to ring main units 5 suitable for use in 11KV underground reticulation, and to operating handles therefor.

In the past, ring main units have been provided with operating handles for switching them on and off. However, if a switch is accidentally switched 10 on in error, and causes a short circuit, the operator's natural reaction upon realising his error is to switch it off again immediately, instead of leaving it to blow a fuse. The action of switching it off while a current is flowing can cause arcing and 15 an explosion. This may cause serious damage to the equipment and to the operator.

It is an object of the present invention to provide a means of overcoming the above difficulty.

20 In a first aspect the present invention broadly consists in an operating handle comprising an elongate member formed as two halves pivoted together at their ends to form a pivot in the middle of the handle, the pivot having an 25 abutment so that when one end of the handle is urged in one angular direction the handle can collapse from a first position in which the two halves are substantially aligned with each other to a second position in which one half is folded over 30 with respect to the other half but, when the said one end is urged in the opposite angular direction, the handle remains in its first, substantially aligned configuration, the other end of the handle having an engaging means so that a mechanism 35 can be engaged by the engaging means of the handle and rotated by the handle.

In a second aspect the present invention broadly consists in a high voltage switch comprising a fixed contact and a movable contact, 40 the movable contact being movable into and out of engagement with the fixed contact by means of an actuating mechanism operable by means of an operating handle as defined above.

In a third aspect the present invention broadly 45 consists in a switch arrangement comprising a housing, a first and second high voltage switch mounted within the housing, each switch being a high voltage switch as defined above, the fixed contacts being electrically connected together 50 and to an electrode fixed to the exterior of the housing.

In a fourth aspect the present invention broadly consists in a ring main unit comprising three three-switch units as defined above, all positioned 55 side-by-side within a single housing, one switch of each switch arrangement being electrically connected by a bus bar with a corresponding switch in each of the other two three-switch units.

60 The above gives a broad description of the present invention, a preferred form of which will now be described with reference to the accompanying drawings in which:

Figure 1 is a side view of a switch arrangement

65 for use with the present invention,

Figure 2 is an end view of the switch arrangement of Figure 1,

Figure 3 is a longitudinal view of a pair of fixed and moving contacts,

70 Figure 4 is a cross-sectional view of a moving contact and its housing,

Figure 5 is an explosed view of one operating mechanism in its "elosed" position,

Figure 6 is an exploded view of the operating 75 mechanism in its "open" position,

Figure 7 is a side view of the operating mechanism, and

Figure 8 is a side view of an operating handle of the present invention.

80 In its preferred form, the switch gear of the present invention is mounted in a housing 1 and comprises a pair of fixed contacts 2, 3 which are electrically connected together and a corresponding pair of movable contacts 4, 5 85 which are longitudinally slidable into and out of contact with the fixed contacts. The movable contact 4 is vertically movable along a spring loaded slide 6 to move into or out of a socket within the fixed contact 2 and the movable 90 contact 5 is horizontally movable within its housing 7 to move into or out of a socket within the fixed contact 3. The fixed contacts 2 and 3 are together connected to an electrode 9 mounted on the underside of the housing.

95 As shown in Figure 2 the switching arrangements are arranged in groups of three, side-by-side within a three-switch tank, these in turn being arranged in groups of three, to form a ring main unit. Thus in Figure 2 there are seen 100 three groups of three fixed contacts 2, movable contacts 4 and electrodes 9. Each horizontally movable contact 5 is connected to a respective one of a set of three bus bars 10 which interconnect the three groups of switches in the 105 normal manner to form a ring main unit. The vertical moving contacts 4 when engaged with the respective fixed contacts 2 connect the electrodes 9 to earth. Thus the vertical switches may also be referred to as earth switches, while 110 the horizontal switches may be referred to as main switches.

Each group of three main switches and each group of three earth switches within a three-switch tank are operated together by a respective 115 switch operating mechanism 11 which is in turn operated by a respective operating boss 12 engageable by an operating handle 13 as shown in Figure 8. The purpose of the operating mechanisms 11 is to ensure quick positive 120 operation of the switches regardless of the manner in which the operating bosses 12 are actuated. The ring main unit of Figures 1 and 2 has six substantially identical operating mechanisms for operating the six sets of three 125 switches.

When in use, the housing 12 is filled with oil up to the level A shown in Figure 1. The oil provides an insulating medium to prevent current leakage or arcing between the various current-carrying

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GB 2 113 918 A 2

components of the switches when the unit is used in high voltage operation.

Figures 3 and 4 show a pair of fixed and moving contacts. It illustrates the contact 3 and 5 5 of a main switch unit but the contacts 2 and 4 of an earth switch unit are similar. Each fixed contact 3 comprises a hollow cylinder, typically of tellurium copper, open at one end 14 where the internal surface of the cylinder is flared to assist 1 o the entry of a moving contact 5. The flares also serve to protect the normal current-carrying part of the contacts from arcing. The hollow cylinder has a plurality of slots 15 extending parallel to the axis of the cylinder from the flared end inwardly, 15 leaving a plurality of petals 16 which define a cylindrical space between them. Adjacent the fiared end of the cylinder is an annular ridge extending into the cylindrical space, and broken only by the slots 15. Thus, when moving a contact 20 5 engages the fixed contact the only point of engagement is a line around the annular ridge. This prevents the movement of the movable contact from being impeded by friction building up along the inside wall of the cylindrical contact 25 3 as the moving contact 5 passes into it.

Positioned around the outside of the petals 16 is a heiical garter spring 20, typically made of a phosphor bronze alloy material. The tight engagement of the garter spring around the 30 contacts prevents chatter of the petals when they are struck by the moving contact as it makes initial contact with the fixed contact. In some applications, however, the garter spring may be omitted.

35 The moving contact 5 is in the form of a longitudinally slidable, cylindrical mandrel, typically of copper, siidably located within a fixed guide housing 7, typically of brass. A pair of plates or fingers 21 is fixed to the housing, one plate on 40 each side of the housing as shown in Figure 4, so that each plate is in frictional contact with the side of the mandrel 5. Thus, electrical contact is ensured between the mandrel 5 and the plates 21, which is a more effective contact than the 45 copper to brass contact between the mandrel and the housing. The plates are directly connected to a copper strip 22 which is fixed to the respective bus bar 10.

Figures 5 to 7 illustrate in detail the operating 50 mechanism 11 for each set of switches. Figure 7 is a side view of an earth switch mechanism 11, the main switch mechanism being similar, however. Figures 5 and 6 are exploded views of the mechanism 11 in its two rest positions, the 55 details shown in Figure 5 and 6 being equally applicable to an earth switch and a main switch mechanism.

The mechanism comprises a drive plate 23 fixed to a shaft 24 which is directly connected to 60 the respective operating boss 12 shown in Figures 1 and 2. Fixed to the drive plate 23 is a pair of studs 25, one of which rests against the side of a crank 29 in each of the two rest positions of the mechanism.

65 The crank 29 comprises a pair of plates 30

interconnected at one end by a hollow tube 31 which slidingly fits over the shaft 24, and at the other end by a bearing pin 32.

An aperture 33 of a slide link 34 fits over the 70 pin 32, the slide link 34 also having an elongate slot 35 for engaging the pin 39 of a drive trunnion 40.

The trunnion 40 also has an aperture 41 which fits rotatably over the tube 31 of the crank, and an 75 elongate aperture 42 through which the pin 32 of the crank passes without contacting the trunnion.

Also mounted on the crank pin 32 is an aperture 43 of a rocker member 44, upon which there is mounted a pair of compression springs 80 45. At the other end the springs 45 are mounted on a second rocker member 49 pivoted to a fixed mounting 50 on the inside wall of the housing 1.

An aperture 42 in the trunnion 40 is connected to a drive link for operating the respective 85 movable switch. In the case of an earth switch, the link may be a simple steel plate 52 connected to the set of three vertically movable contacts 4 in the three-switch tank by means of a link plate 53. In the case of a main switch unit the drive link 90 may comprise a steel rod 54 connected at its top end to a spherical joint 55 secured to the aperture 51 and at its bottom end to a second spherical joint 59 connected to a linkage 60 as shown in Figure 1, which drives all three main switches of 95 the respective unit. The spherical joints allow the side-to-side movement of the top end of the rod 54 to be translated into the forward-backward movement of the bottom end of the rod.

The operation of the operating mechanism is 100 as follows. When the operating boss 12 is rotated, the shaft 24 is rotated with it, thus rotating the drive plate 23. When the mechanism is in the configuration shown in Figure 5 the lower stud 25 of the drive plate is resting against the 105 side of the crank 29. Thus, rotation of the drive plate 23 causes the drive stud 25 to propel the crank 29 from the vertical position show in Figure 5 towards the horizontal position shown in Figure 6. The pin 32 is thus swung upwardly carrying the 110 slide 34 and the upper rocker member 44 with it. During the first part of the movement the slot 35 slides along the pin 39 so that the trunnion 40 is not affected. As the pin 32 moves in an arc, the movement of the rocker member 34 compresses 115 the spring 45 until the longitudinal axis of the crank 29 is aligned with the springs 45. As the shaft 24 continues to be rotated the crank and springs pass their over-centre position and the springs expand under their natural resilience to 120 propel the crank 29 firmly towards the horizontal position shown in Figure 6. Also at this stage the end of the slot 35 engages the pin 39 of the trunnion so that as the crank is propelled suddenly towards its horizontal position, the 125 trunnion 40 is also rotated about its aperture 41, thus actuating the drive link 52 or 54. The movable contacts of the switch unit are thus quickly and firmly disengaged from their respective fixed contacts.

130 To reconnect the contacts, the switch is

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GB 2 113 918 A 3

operated in the opposite direction, the operation being the reverse of that described above. The upper stud 25 engages the upper side of the crank 29 and urges it downwardly until the crank 5 and spring reach their centre position at which point the other end of the slide 35 engages the pin 39 of the trunnion. Continued movement of the shaft pushes the crank past its over-centre position and the compressed springs 45 propel 1 o the crank, and hence the slide 34, and hence the trunnion 40, back to the position shown in Figure 5. The switches are thus quickly and firmly reengaged.

Figure 8 illustrates the preferred operating 15 handle 13 for use with the operating mechanism

11 described above. The handle comprises a pair of elongate members 61, 62 connected together at a central pivot point 63. The elongate members have a pair of abutments 64, 65 which hold the

20 handle rigid when a downward rotational force is applied to one end of the handle as shown in the drawing. However, when an upward rotational force is applied to one end of the handle, the handle pivots about the pivot point 63 so that the 25 rotational force is not transmitted to the other end of the handle. At each end of the handle there is a shaped aperture, 66, 67 for engaging a respective operating boss 12. The two apertures 66 and 67 are differently shaped, as are the two operating 30 bosses 12, so that the same end of the handle cannot be used for operating both bosses of a switch unit i.e., one end is for actuating the main switch units, the other for the earth switch units.

Alternatively, the handle may have a stud at 35 each end for engaging complementary sockets in the ends of the shafts 24. In use, the appropriate end of the handle is attached to the selected boss

12 to operate the switches. The handle has to be connected the right way round to operate the

40 boss in the required direction. If a switch is switched on in error, and causes a short circuit, the switch cannot be switched off again immediately as would be the operator's natural reaction when he realises what he had done. If a 45 short was immediately disconnected again, there would be arcing and an explosion. However, when he attempts to switch it off again, the handle merely pivots about the pivot point 63 so that the switch remains on. By the time an operator has 50 removed the handle to turn it around, he ought to have realised that it would be a mistake to attempt to disconnect the circuit, but even if it does continue to turn the handle around and operate the switch in the other direction, a 55 contact breaker further along the line will have already disconnected the circuit in the proper manner.

Thus the handle provides a safety mechanism which prevents explosion of the switch gear in the 60 event of an inadvertent short circuit caused by a human operator.

A ring main unit made according to the teaching of the present specification may be typically 1000 mm. in height, 620 mm. deep and 65 750 mm. wide. The three-switch tank is designed so that three fuses can be accommodated in it, in series with the centre switch.

The present invention thus provides a high voltage switch unit which can be made of smaller 70 overall size than prior art switch units of similar capabilities, as well as being lower in cost. The switch unit of the invention permits dry type terminations of cables to be used. The unit can also be used outdoors without having to be put 75 inside a separate weather tight enclosure. The housing can be made weather proof without any further enclosures being required.

Many modifications to the above may be made without departing from the scope of the present 80 invention as broadly defined. For example single switch units may be provided or single three-phase switch tanks. The switch units may be extensible or non-extensible, fused or non-fused. The arrangements of vertical and horizontal 85 sliding contacts can be altered, although this may affect the overall dimensions of the switch units.

Claims (11)

Claims

1. An operating handle comprising an elongate member formed as two halves pivoted together at

90 their ends to form a pivot in the middle of the handle, the pivot having an abutment so that when one end of the handle is urged in one regular direction the handle can collapse from a first position in which the two halves are 95 substantially aligned with each other to a second position in which one half is folded over with respect to the other half but, when the said one end is urged in the opposite angular direction, the handle remains in its first, substantially aligned

100 configuration, the other end of the handle having an engaging means so that a mechanism can be engaged by the engaging means of the handle and rotated by the handle.

2. A handle as claimed in Claim 1, wherein the

105 engaging means comprises a non-circular aperture for engaging a complementary non-circular end of a shaft.

3. A handle as claimed in Claim 1, wherein the engaging means comprises a non-circular

110 extension for engaging a complementary non-circular aperture in a rotatable mechanism.

4. A handle as claimed in Claim 1, 2 or 3, wherein there is a said engaging means at each end of the handle.

115

5. A handle as claimed in Claim 4, wherein the engaging means at each end of the handle are non-identical.

6. An operating handle substantially as herein described with reference to Figure 8 of the

120 accompanying drawings.

7. A high voltage switch comprising a fixed contact and a movable contact, the movable contact being movable into and out of engagement with the fixed contact by means of

125 an actuating mechanism operable by means of an operating handle as claimed in any preceding claim.

8. A switch arrangement comprising a housing, a first and second high voltage switch mounted

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GB 2 113 918 A 4

within the housing, each switch being a high voltage switch as defined in Claim 7, the fixed contacts being electrically connected together and to an electrode fixed to the exterior of the 5 housing.

9. A switch arrangement as claimed in Claim 8 wherein one of the movable contacts is adapted to be moved horizontally into and out of its fixed contact and the other movable contact is adapted

10 to be moved vertically into and out of contact with its fixed contact.

10. A ring main unit comprising three three-phase switch units as claimed in Claim 9, all positioned side-by-side within a single housing, one switch of each switch arrangement being

100 electrically connected by a bus bar with a corresponding switch in each of the other two three-phase switch units.

Printed for Her Majesty's Stationery Office by the Courier Press, Leamington Spa, 1983. Published by the Patent Office. 25 Southampton Buildings, London, WC2A 1AY, from which copies may be obtained

10. A switch arrangement as claimed in Claim 8 or 9, wherein the housing is adapted to be oil-filled.

15

11. A three-phase switch unit comprising three switch arrangements as claimed in any one of Claims 8 to 10, all positioned side-by-side within a single housing the first switches all being actuable by a single actuating means and the 20 second switches all being actuable by a second single actuating means.

12. A ring main unit corresponding three three-phase switch units as claimed in Claim 11, all positioned side-by-side within a single housing,

25 one switch of each switch arrangement being electrically connected by a bus bar with a corresponding switch in each of the other two three-phase switch units.

13. A high voltage switch as claimed in Claim 30 7, substantially as described by way of reference to the accompanying drawings.

New claims or amendments to claims filed on 22 March 1983 Superseded claims All

35 New or amended claims:—

1. An operating handle comprising an elongate member formed as two halves pivoted together at their ends to form a pivot in the middle of the handle, the two halves having cooperating 40 abutments arranged so that when one end of the handle is urged in one angular direction the handle can collapse from a first position in which the two halves are substantially aligned with each other with the abutments in contact with each 45 other to a second position in which one half is folded over with respect to the other half but, when the said one end is urged in the opposite angular direction, the handle remains in its first, substantially aligned configuration, each end of 50 the handle having an engaging means so that a mechanism can be engaged by the engaging means of the handle and rotated by the handle, said engaging means at opposite ends of the handle being non-identical.

55 2. A handle as claimed in Claim 1, wherein the engaging means at each end comprises a non-circular aperture for engaging a complementary non-circular end of a shaft.

3. A handle as claimed in Claim 1, wherein the

60 engaging means at each end comprises a non-

circular extension for engaging a complementary non-circular aperture in a rotable mechanism

4. An operating handle substantially as herein described with reference to Figure 8 of the

65 accompanying drawings.

5. A high voltage switch comprising a fixed contact and a movable contact, the movable contact being movable into and out of engagement with the fixed contact by means of

70 an actuating mechamism operable by means of an operating handle as claimed in any preceding claim.

6. A switch arrangement comprising a housing, a first and second high voltage switch mounted

75 within the housing, each switch being a high voltage switch as defined in Claim 5, the fixed contacts being electrically connected together and to an electrode fixed to the exterior of the housing.

80 7. A switch arrangement as claimed in Claim 6 wherein one of the movable contact is adapted to be moved horizontally into and out of its fixed contact and the other movable contact is adapted to be moved vertically into and out of contact

85 with its fixed contact.

8. A switch arrangement as claimed in Claim 6 or 7, wherein the housing is adapted to be oil-filled.

9. A three-phase switch unit comprising three

90 switch arrangements as claimed in any one of claims 6 to 8, all positioned side-by-side within a single housing the first switches all being actuable by a single actuating means and the second switches all being actuable by a second

95 single actuating means.