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Patent Searching and Data


Title:
IMPROVEMENTS RELATING TO ELECTRIC POWER DISTRIBUTION
Document Type and Number:
WIPO Patent Application WO/1994/005063
Kind Code:
A1
Abstract:
A saddle device, for an electric motor control centre power distribution arrangement, including lever actuation means (14) for effecting engagement and disengagement of a plurality of power supply connection members (11) carried on the saddle device with corresponding power supply connection members (12) carried on racking for accommodating such saddle devices. The lever actuation means may be formed with a camming slot (16) for engagement with a static pin (17) located on said racking, in use. The device may include power supply switching means (22) including an arrangement (23) for preventing insertion or removal of the saddle device whilst said control switching means (22) is in its "ON" position.

Inventors:
NEILL, Kenneth CLARKE, Geoffrey.
Application Number:
PCT/GB1992/001456
Publication Date:
March 03, 1994
Filing Date:
August 17, 1992
Export Citation:
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Assignee:
SQUARE D COMPANY.
International Classes:
H01R13/629; H01R13/707; H02B1/36; H02B11/127; (IPC1-7): H02B11/127; H02B1/36
Foreign References:
US4768967A
US3343042A
US4831489A
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Claims:
Claims
1. A saddle device, for an electric motor control centre power distribution arrangement, including lever actuation means for effecting engagement and disengagement of a plurality of power supply connection members carried on the saddle device with corresponding power supply connection members carried on racking for accommodating such saddle device.
2. A device as claimed in claim 1 wherein such lever actuation means is formed with a camming slot for engagement with a static pin located on said racking, in use.
3. A device as claimed in claim 1 or 2 including power supply switching means including an arrangement for preventing insertion or removal of the saddle device whilst said control switching means is in its "ON" position.
4. A device as claimed in claim 3 wherein said prevention arrangement comprises a member located on an actuation shaft for said switching means, said member when in its "ON" position, being locatable with the lever actuation means when the lever is in its "closed" position and locatable to prevent actuation of the lever actuation means when the lever is in its "open" position.
5. A device as claimed in any preceding claim wherein said power supply connection means are located in an offset position relative to the centre line of such saddle device in its direction of movement for engaging or disengaging with said racking, in use.
6. A device as claimed in claims 2 and 5 wherein said static pin and the pivot point for the lever means are positioned so as to be generally centrally located relative to said power supply connection means.
7. A plurality of devices as claimed in any preceding claim located in racking therefor, said racking including latching means for retaining each said device in said racking.
Description:
Improvements Relating to Electric Power Distribution

The invention relates to electric power distribution arrangements and more particularly to saddle devices for use with electric motor control centre power distribution arrangements.

Typical motor control centres comprise a group of motor starters contained in one or more vertical columns, each column containing a number of motor starters. Each starter is contained in a saddle which has rearwardly projecting power supply connection members for plugging onto vertical busbars.

To ensure reliable electrical connections, substantial forces are required between the vertical busbars and the saddle. Considerable manual effort is required both to plug-on and to withdraw the saddle from the vertical busbars. The provision of handles on the saddle door is an aid but does not reduce the physical force required which may be in the order of tens to over one hundred pounds.

It is an object of the invention to obviate or mitigate the above disadvantages.

According to the invention there is provided a saddle device, for an electric motor control centre power distribution arrangement, including lever actuation means for effecting engagement and disengagement of a plurality of power supply connection members carried on the saddle device with corresponding power supply connection members carried on racking for accommodating such saddle device.

The lever actuating means may be formed with a camming slot for engagement with a static pin located on said racking, in use.

Preferably the saddle includes power supply switching means including an arrangement for preventing insertion or removal of the saddle device whilst in its "ON" position.

Such prevention arrangement may comprise a member located on an actuation shaft for said switching means, said member when in its "ON" position, being locatable

with the lever actuation means when the lever is in its "closed" position and locatable to prevent actuation of the lever actuation means when the lever is in its "open" position.

The power supply connection means may be located in an offset position relative to the centre line of such saddle device in its direction of movement for engaging or disengaging with said racking, in use. With such an arrangement said static pin and the pivot point for the lever means may be positioned so as to be generally centrally located relative to the power supply connection means.

A plurality of the saddle devices of the next preceding five paragraphs may be located in racking therefor, said racking including latching means for retaining each said device in said racking.

The foregoing and further features of the invention may be more readily understood from the following description of a preferred embodiment thereof, by way of example, with reference to the accompanying drawings, in which:-

Figs. 1A, IB and 1C show diagrammatic plan views of a saddle device in engaged, partially disengaged and completely disengaged positions, respectively with respect to racking of a motor control centre; _ Figs. 2A, 2B and 2C show diagrammatic front elevational views of Figs. 1A, IB and 1C respectively;

Fig. 3 shows a front elevational view, on reduced scale, of a portion of racking for a motor control centre with saddle devices of Figs. 1 and 2 located therein, and

Figs. 3A and 3B are enlarged views of the dashed portions IIIA and IIIB in Fig. 3.

Referring now firstly to Figs. 1 and 2 there is shown a saddle device, for a motor control centre, which comprises a mounting assembly framework 10 having three power supply connection contacts 11 mounted at the rear

thereof for engagement with respective vertically extending busbars 12 in the motor control centre racking 13 (Fig. 3) .

A lever 14 is pivotally mounted on framework 10 about pivot point 15 and is formed with a camming slot 16 which is engageable with a static pin 17 located on the racking 13. A latch member 18 is pivottally mounted at point 19 to racking 13 and is resiliently urged to its closed position by a spring 20.

A square section actuation shaft 21 of a power supply switch 22 carries a member 23 thereon which prevents insertion and withdrawal of saddle device 10 from racking 13 when the switch 22 is in its "ON" position as will hereinafter be more fully described.

Referring now to Fig. 3 there is shown a portion of the racking 13 for a motor control centre (MCC) with two saddle devices 10 located therein, each such device including a cover door 24 attached by hinges 25 as more clearly shown in Fig. 3A. In addition to latch 18 for retaining saddle device framework 10 in position in racking 13, two screw fixings 26 are provided, particularly for use in transit, as more clearly shown in Fig. 3B.

In use, when it is required to remove a saddle device from racking 13, switch 22 is rotated counter-clockwise to rotate shaft 21 and hence move member 23 from its position shown in Figs. 1A and 2A, engaged with lever 14, to its position as shown in Figs. IB and 2B and cover door 24 opened. The latch 18 is then moved to the position as shown in Fig. IB and lever 14 pivotted about point 15 so that interaction between slot 16 and pin 17 causes retraction of contacts 11 from busbars 12. Further rotation of lever 14 to the position shown in Fig. lc causes disengagement of slot 16 from pin 17 and of contacts 11 from busbars 12 so that the saddle device can be completely removed from racking 13. The reverse action is undertaken to replace the saddle device in racking 13. \' With the arrangement shown there is greater freedom

for the MCC designer to choose the location of the vertical busbar. The points at which the vertical busbars join horizontal busbars 27 are dependent on horizontal busbar bracing and splicing areas. In order to avoid those areas and to avoid bending and forming of the vertical busbars 12, the vertical busbars 12 may not be on the centre line of the saddle. When the vertical busbars 12 are off-centre with respect to the saddle, plugging-on and withdrawal are difficult because the saddle tends to move sideways and jam. Since the saddle lever fulcrum 15 and pin 17 can be located adjacent to the centre line of the vertical busbars 12 the sideways moment is practically eliminated resulting in a smooth action.

By inclusion of lever 14, the manual forces required for insertion and withdrawal of the saddle can be reduced by a factor of at least 6:1. This is especially advantageous for saddles which are less accessible, i.e. those at the top and those at the bottom of the vertical column(s) . This also allows the force on the saddle contacts 11 to be applied in an even and controlled manner reducing the risk of mechanical damage to the equipment. That damage can occur if the saddle is slammed into position using the momentum of the saddle to overcome the saddle contact closing force.

It is very important to ensure that the saddle cannot be connected or disconnected from the vertical busbars 12 with the switch 22 in the closed position. That could result in arcing and a flashover, severly damaging the MCC. The inclusion of plate 23 attached to the shaft 21 of switch 22 prevents the saddle from being disconnected with the switch 22 in the closed position. This is accomplished by arranging plate 23 to enter slot 28 in the saddle lever 14 with switch 22 closed, effectively locking the saddle lever 14.

The reverse is also true, i.e. switch 22 can only be closed with saddle in the fully plugged in or fully withdrawn positions. In the latter case with the switch 22 closed the saddle cannot be fully or partially plugged-

in due to the inside edge of the saddle lever 14 being obstructed by plate 23. .