ELECTRICAL DISTRIBUTION BOARDS

Abstract: An electrical distribution board comprises, in fixed spatial relationship, a DIN rail constituted by a pair of separate rail elements constituting the functional edges of the DIN rail and a busbar. The DIN rail and the busbar serve to mount an electrical protective device (such, for example, as an MCB). One of the rail elements of the DIN rail is pivotally movable from a position of engagement with a locating formation of an electrical protective device to permit easy fitment of the device to the distribution board, or removal therefrom, without requiring disconnection of the busbar from the board. As a result the known difficulties of mounting and dismounting DIN rail mounted circuit protective devices in the presence of a fixed busbar in factory built assemblies are avoided.

Description: ELECTRICAL DISTRIBUTION BOARDS This invention relates to electrical distribution boards. An electrical distribution board is, as is well known, connected to an electrical power supply and serves to distribute the power supply to desired locations or equipment through electrical protective devices such, for example, as fuses, miniature circuit breakers (MCBs) and residual current devices (RCDs) . These devices are electrically connected to the power by a common connection usually in the form of a busbar on the distribution board and are conveniently mounted on a fixed rail known as a DIN rail (a rail in the shape of an inverted shallow top hat), so called because of its origin within a German Standard - Deutsche Industrie Norm. A DIN rail has two opposed outwardly projecting edges which engage within recesses in the base of mounted equipment such, for example, as an MCB. One recess is fixed being usually formed integral with the body of the MCB, while the other is formed, in part, by a resiliently-loaded clip displaceable as the MCB is engaged with the DIN rail. When fully engaged, the resilient clip of the MCB returns under the action of its resilient loading to engage fully under the respective edge of the DIN rail. This arrangement is diagrammatically illustrated in the Figure marked "PRIOR ART" in the accompanying drawings. Distribution boards may be factory assembled or alternatively the components making up same may be fitted and connected together on site by cables. Factory assembly permits lower cost production under controlled conditions as opposed to on-site assembly which is labour intensive, and which may subject the equipment to hazards such as dust, damp and physical damage. Factory built assemblies (FBAs) are normally provided with a rigid busbar mounted on insulating supports which in turn are fixed to the structure of the distribution board. Individual circuit protective devices (MCBs for example) are mounted on the fixed DIN rail as described above with their terminals suitably positioned for direct connection to the busbar. However if both the DIN rail and the busbar are fixed as is diagrammaticially illustrated in the Figure marked "PRIOR ART" in the accompanying drawings, it is not normally possible to add or change an outgoing circuit protective device due to the mutually opposing edges of the DIN rail and the fixed busbar. It is therefore usually necessary to remove the busbar in such circumstances which involves disconnecting it from its supports, every outgoing circuit protective device, and any incoming supply connection. This is not necessary in a site built assembly where the common connection is formed by loops of flexible cable which can be moved out of the way when an outgoing circuit device is mounted or dismounted from the DIN rail. It is an object of the present invention to overcome the difficulties of mounting and dismounting DIN rail mounted circuit protective devices in the presence of a fixed busbar in factory built assemblies. According to the present invention, therefore, there is provided an electrical distribution board comprising a pair of separate rail elements constituting the functional edges of a DIN rail for mounting an electrical protective device (such, for example, as an MCB) and whereof one of the rail elements is pivotally movable from a position of engagement with a locating formation of a circuit protective device to permit easy fitment of the device to the distribution board, or removal therefrom, without requiring disconnection of the busbar and other devices from the board. Preferably the pivotal rail element at an end thereof is connected to a pivotal arm pivotally linked to a pivotal over-centre toggle lever. Preferably the pivotal rail element has a tube formation at one edge to provide necessary torsional rigidity, the rail element being secured to the pivotal arm which has a forked end pivotally receiving one end of a link, whereof the other end is pivotally received in a forked end of the toggle lever. The pivotal assembly of linked arm and toggle lever may be spring-assisted to both rail element engaged and rail element disengaged positions. This pivotal assembly may be duplicated, one at each end of the pivotal rail element. Alternative rail element moving and locking means may be provided. For example, the tubular formation of the pivotal rail element may house an operating rod rotatable to cause pivoting of the rail element through connections between the operating rod and tubular formation, the rod being operated from an end of the rail element and there being releasable means for locking the rail element in its device engagement and disengagement positions. An embodiment of the present invention will now be described, by way of example, with reference to the accompanying drawings, in which:- Fig. 1 is a perspective view of a distribution board according to the present invention; Fig. 2 is a sectional side view of the distribution board; Fig. 3 is a perspective detail view of the distribution board; and Figs. 4 and 5 are side views showing the pivotal rail element and the operating mechanism therefor in device engaged and device disengaged positions respectively. The electrical distribution board is generally indicated at 10 and comprises a baseplate 11. The distribution board 10 is fitted, as is usual, with a power supply busbar 12, detail of which is shown in Fig. 3. The distribution board 10 has an arrangement for mounting a series of, for example, MCBs 13, each of which has on one face remote from its switch 14 a fixed locating formation 15 and a spring-loaded locating formation 16 spaced from and directed towards one another. The mounting arrangement comprises a DIN rail consisting of a fixed rail element 17 and a pivotal rail element 18 engagable respectively by formations 15 and 16 of the MCB 13. The busbar 12 is slotted as indicated at 19 to receive a series of side-by-side MCBs 13 (see Fig. 1) in electrical connection via screws or bolts 20. The pivotal rail element 18 has at one edge a tube formation 21 and is rotatably supported, at one end, in a bracket 22 and connected, at its other end, to an arm 23 pivotally connected to a plate 24 connected to and at right angles to the baseplate 11. The arm -23 has a forked end 23A which is pivotally connected to one end of a link 25, whereof the other end is pivotally connected in the forked end 26A of an over-centre toggle lever 26 also pivoted to the plate 24. The pivotal connection between the link 25 and the forked end 26A of the toggle lever 26 has a lateral extension 27 engagable in an arcuate slot 28 in the plate 24. The toggle lever 26 has at its free end a finger grip 29. > The MCB-engaging position of the rail elements 17, 18 is shown in Fig. 4. To facilitate release of an MCB 13 or the engage an MCB 13 the toggle lever 26 is moved to the position shown in Fig. 5 where, it can be seen, the rail element 18 is pivoted to a position adjacent the baseplate 11. An MCB 13 can be readily engaged on the rail elements 17, 18 when the rail element 18 is in the MCB-engaging position shown in Fig. 4 due to the spring-loaded locating formation 16. A cover (not shown) is provided to engage the baseplate 11 and enclose the DIN rail constituted by rail elements 17 and 18 and the busbar 12 and the MCBs and other electrical protective devices.

Claims: CLAIMS 1. A DIN rail for an electrical distribution board and comprising a pair of rail elements constituting the functional edges of the DIN rail for mounting an electrical protective device (such, for example, as an MCB), the DIN rail being characterised in that one of the rail elements is pivotally movable from a position of engagement with a locating formation of an electrical protective device to permit easy fitment of the device on ' the DIN rail, or removal therefrom. 2 . A DIN rail as claimed in claim 1 comprising a baseplate mounting the rail elements with the pivotal rail element being rotatably supported at its ends by brackets or plates on the baseplate. 3. A DIN rail as claimed in claim 1 or 2 in which the pivotal rail element at one end thereof is connected to a pivotal arm pivotally linked to a pivotal over-centre toggle lever. 4. A DIN rail as claimed in claim 3 in which the pivotal rail element has a tube formation at one edge to provide torsional rigidity, the rail element being secured to the pivotal arm which has a forked end pivotally receiving one end of a link, whereof the other end is pivotally received in a forked end of the toggle lever. 5. A DIN rail as claimed in claim 3 or 4 in which the pivotal assembly of linked arm and toggle lever is spring- assisted to both rail element engaged and rail element disengaged positions. 6. A DIN rail as claimed in any one of claims 3 to 5 in which a pivotal assembly of linked arm and toggle lever is provided at each end of the pivotal rail element. 7. A DIN rail as claimed in claim 1 or 2 in which the pivotal rail element has a tube formation at one edge to provide torsional rigidity and housing an operating rod rotatable to cause pivoting of the rail element through - 7 - connections between the operating rod and tube formation, the rod being operable from one end of the rail element and there being releasable means for locking the rail element in its device engagement and disengagement positions. 8. An electrical distribution board comprising, in fixed relative positions for mounting an electrical protective device (such, for example, as an MCB), a DIN rail constituted by rail elements and a busbar, the electrical distribution board being characterised in that one of the rail elements of the DIN rail is pivotally movable from a position of engagement with a locating formation of an electrical protective device to permit easy fitment of the device to the distribution board, or removal therefrom, without requiring disconnection of the busbar from the board. 9. An electrical distribution board as claimed in claim 8 in which the DIN rail comprises a baseplate mounting the rail elements with the pivotal rail element being rotatably supported at its ends by brackets or plates on the baseplate. 10. An electrical distribution board as claimed in claim 8 or 9 in which the pivotal rail element at one end thereof is connected to a pivotal arm pivotally linked to a pivotal over-centre toggle lever. 11. An electrical distribution board as claimed in claim 10 in which the pivotal rail element has a tube formation at one edge to provide torsional rigidity, the rail element being secured to the pivotal arm which has a forked end pivotally receiving one end of a link, whereof the other end is pivotally received in a forked end of the toggle lever. 12. An electrical distribution board as claimed in claim 10 or 11 in which the pivotal assembly of linked arm and toggle lever is spring-assisted to• both rail element engaged and rail element disengaged positions. 13. An electrical distribution board as claimed in any one of claims 10 to 12 in which a pivotal assembly of linked arm and toggle lever is provided at each end of the pivotal rail element. 14. An electrical distribution board as claimed in claims 8 or 9 in which the pivotal rail element has a tube formation at one edge to provide torsional rigidity and housing an operating rod rotatable to cause pivoting of the rail element through connections between the operating rod and tube formation, the rod being operable from one end of the rail element and there being releasable means for locking the rail element in its device engagement and disengagement positions.

Inventors: KIDD ALAN LISTER, KIDD, ALAN, LISTER
Applicants: SCHOLES GROUP PLC
Application year: 1989
Main classification: H02B1
IPC codes: H02B1