Safety system

Abstract

A device and a system for preventing insertion of a fuse into a fuse holder, and methods for using the same. The device and the system comprise retaining elements that are adapted to engage with a fuse holder. When the device or system is engaged in a fuse holder, it is not possible to insert a fuse into the fuse holder. This allows for safe isolation of electric circuits.

Claims

1. A fuse insertion prevention device for preventing insertion of a fuse into a fuse holder, comprising: a plurality of retaining elements configured to engage with the fuse holder, and a resilient member situated between the plurality retaining elements, wherein: the plurality of retaining elements are moveable relative to each other between an engaged and a released position, such that: in the engaged position, the resilient member exerts pressure on the plurality of retaining elements thereby urging them apart, and in the released position, the plurality of retaining elements are moved towards each other and the resilient member is compressed, and the fuse insertion prevention device further comprises a core body including a cavity having dimensions configured to: house a stem region of the plurality of retaining elements and the resilient member, and allow for movement of the plurality of retaining elements encompassed therein in a single plane along a longitudinal axis of the fuse insertion prevention device between the released and engaged positions.

2. The fuse insertion prevention device according to claim 1, wherein the resilient member is a spring.

3. The fuse insertion prevention device according to claim 1, wherein: each of the plurality of retaining elements comprises an actuator tab, the stem region, and a foot, the actuator tab and the foot are at respective ends of the stem region, and the foot and the actuator tab lie in a plane that is perpendicular to a longitudinal axis of the stem region.

4. The fuse insertion prevention device according to claim 3, wherein: the fuse insertion prevention device further comprises an aperture, and dimensions of the aperture are such that the actuator tabs of the plurality of retaining elements protrude through the aperture and can move between the released and engaged position.

5. The fuse insertion prevention device according to claim 3, wherein the foot of each of the plurality of retaining elements comprises a plurality of projections that are configured to engage the fuse holder.

6. The fuse insertion prevention device according to claim 3, wherein a leading edge of each of the actuator tabs is angled.

7. The fuse insertion prevention device according to claim 3, wherein: the fuse insertion prevention device is configured to be gripped by a fuse puller by means of one or more ridges on the outside of the fuse insertion prevention device which demarcate the areas where the fuse puller contacts the fuse insertion prevention device, and the fuse puller is configured to press the actuator tabs of the plurality of retaining elements thereby moving the plurality of retaining elements from the engaged position to the released position.

8. The fuse insertion prevention device according to claim 1, wherein: the core body is shaped for insertion into the fuse holder, and the core body comprises a cylindrical element or is cylindrical.

9. The fuse insertion prevention device according to claim 1, wherein the plurality retaining elements are configured to engage ends of the fuse holder, respectively.

10. The fuse insertion prevention device according to claim 1, wherein: the cavity comprises a recessed groove, each of the plurality of retaining elements comprise a ridge, the ridge and the recessed groove interlock and the ridge moves in the recessed groove in a single plane along the longitudinal axis of the fuse insertion prevention device on compression and release of the resilient member, and the ridge protrudes from the stem region of each of the plurality of retaining elements.

11. The fuse insertion prevention device according to claim 1, wherein: each of the plurality of retaining elements comprises a notch, dimensions of the notch are such that each end of the resilient member sits in the notch of a respective retaining element of the plurality of retaining elements, and the notch is in the stem region of each of the plurality of retaining elements.

12. The fuse insertion prevention device according to claim 1, wherein: each of the plurality of retaining elements includes a locking tab comprising an indent or hole, the locking tab lies in a plane that is perpendicular to a longitudinal axis of the stem region of each of the plurality of retaining elements, and in the engaged position the indent or hole in each of the locking tabs aligns with an aperture that runs from one side of the core body to another side of the core body, thereby allowing for a securing member to pass through the aperture and fix the plurality of retaining elements in situ in the core body.

13. The fuse insertion prevention device according to claim 1, wherein the fuse insertion prevention device further comprises a cover element.

14. The fuse insertion prevention device according to claim 1, wherein the fuse insertion prevention device is non-conductive.

15. A fuse-insertion prevention method comprising the steps: providing the fuse insertion prevention device according to claim 1, pressing the actuator tabs of the plurality of retaining elements, thereby moving the plurality of retaining elements towards each other and compressing the resilient member, placing the core body of the fuse insertion prevention device in the fuse holder; and releasing the actuator tabs of the plurality of retaining elements, thereby allowing the resilient member to return to its extended shape and urge the plurality of retaining elements away from each other such that the plurality of retaining elements engage with the respective ends of the fuse holder.

16. A fuse insertion prevention system for preventing insertion of a fuse into a fuse holder, the fuse insertion prevention system comprising: one or more retaining elements configured to engage with a fuse holder; a cover element configured to receive and immobilize the one or more retaining elements and prevents the one or more retaining elements from disengaging from the fuse holder, wherein the cover element prevents insertion of a fuse into the fuse holder; and a core body including a slot running through the core body from an underside to an upperside thereof, the slot including dimensions configured such that: a tab of the one or more retaining elements can pass through the slot in a particular orientation; a stem region of the one or more retaining elements can rotate on its longitudinal axis within the slot; and a foot of the one or more retaining elements cannot enter the slot, wherein the rotation of the stem region enables the one or more retaining elements to be orientated such that: the foot engages with the fuse holder, and the tab prevents release of the one or more retaining elements from the slot in the core body.

17. The fuse insertion prevention system according to claim 16, wherein: the one or more retaining elements comprises a tab, the stem region, and a foot, the tab and the foot are at respective ends of the stem region, and the foot lies in a plane that is perpendicular to a longitudinal axis of the stem region.

18. The fuse insertion prevention system according to claim 16, wherein: the core body is shaped for insertion into the fuse holder, and the core body comprises a cylindrical element for insertion into the fuse holder.

19. A fuse insertion prevention device for preventing insertion of a fuse into a fuse holder, comprising: a plurality of retaining elements configured to engage with the fuse holder, and a resilient member comprising a spring, the resilient member situated between the plurality retaining elements, wherein: the plurality of retaining elements are moveable relative to each other between an engaged and a released position, such that: in the engaged position, the resilient member exerts pressure on the plurality of retaining elements thereby urging them apart, and in the released position, the plurality of retaining elements are moved towards each other and the resilient member is compressed.

Description

DESCRIPTION OF FIGURES

(1) The invention will now be described solely by way of example and with reference to the accompanying drawings in which:

(2) FIG. 1 shows a system of the invention comprising two retaining elements and a cover element, wherein the system is mounted on a fuse holder;

(3) FIGS. 2A and 2B show a system of the invention comprising two retaining elements, a core body and a cover element;

(4) FIGS. 3A, 3B and 3C show a retaining element of the system from various perspectives;

(5) FIGS. 4A and 4B show a cover element from different perspectives;

(6) FIGS. 5A, 5B and 5C show a core body comprising a cylindrical element from various perspectives;

(7) FIG. 6 shows the system of the invention when not in use, i.e., not in a fuse-holder; and

(8) FIG. 7 shows the insertion of the system into a fuse holder;

(9) FIGS. 8A, 8B and 8C show the device of the invention from various perspectives;

(10) FIGS. 9A, 9B, 9C, 9D, 9E and 9F show the retaining element of the device from different perspectives;

(11) FIGS. 10A, 10B and 10C show a first part of the device from various perspectives;

(12) FIGS. 11A, 11B and 11c show a second part of the device from various perspectives, wherein the first and second half of the device interlock to result in an assembled device;

(13) FIGS. 12A and 12B show a cut away view of the device from the side and from the top, respectively;

(14) FIG. 13A shows the retaining elements and the resilient member of the device in the engaged position and FIG. 13B shows a retaining element and a resilient member of the device

(15) FIG. 14A shows the device in the engaged position before being inserted into the fuse holder and before pressure is applied by the fuse puller, FIG. 14B shows the device in the released position wherein the device is gripped by a fuse puller and the fuse puller has exerted pressure on the actuator tabs; and FIG. 14C shows the device in situ in a fuse holder in the engaged position with a locking member.

DETAILED DESCRIPTION

(16) Electrical supply systems, such as signalling systems comprise distribution boards to divide an electrical power feed into subsidiary circuits. Such distribution systems may comprise a plurality of fuse holders, wherein the fuse holders have a metal clip at either end to mount a cartridge fuse. FIGS. 1, 2A and 2B exemplify a single fuse holder (1) having metal clips (2) at each end.

(17) The invention provides a safety device (17) for use in safely and securely isolating one or more subsidiary circuits. The circuit is isolated by removal of the cartridge fuse. The safety device (17) prevents the untimely re-insertion of a cartridge fuse into the fuse holder (1) so as to protect operatives working on the isolated circuit.

(18) FIGS. 8A, 8B and 8C show a device (17) comprising two retaining elements (18a, 18b). A spring (19) (not shown in FIGS. 8A, 8B and 8C) is situated between the two retaining elements (18a, 18b), such that the spring (19) is perpendicular to the retaining elements (see FIG. 12A). The two retaining elements (18a, 18b) are movable between an engaged position, which is depicted in FIGS. 8A, 8B, 8C, and 14C, and a released position, as shown in FIG. 14B. In the engaged position the spring (19) exerts pressure on the two retaining elements (18a, 18b) thereby urging them apart. In the released position the retaining elements (18a, 18b) are moved towards each other and the spring (19) is compressed.

(19) As shown in FIGS. 9A-9F, 13A and 13B, each retaining element (18) comprises an actuator tab (20), a stem region (21), a foot (22) and a locking tab (23). The actuator tab (20) has an angled, chamfer edge (20a). The stem region (21) comprises a ridge (21a) and a notch (21b). The foot comprises three projections (22a, 22b, 22c). The locking tab (23) comprises an indent (23a).

(20) The device (17) comprises a core body (24) and a cover element (28). There is a cavity (25) in the core body (24) for housing the retaining elements (18a, 18b) and the spring (19). In addition, there is a groove (29) in the cavity (25) which interlocks with the ridge (21a) of the retaining elements (18). See FIGS. 10A-10C. The core body (24) further comprises an aperture (27) through which the actuator tabs (20) of the retaining elements (18) protrude when in situ in the core body (24), in both the engaged and released positions. See FIGS. 11A-11C. FIGS. 12A and 12B show the retaining elements (18a, 18b) and the spring (19) in situ within the cavity (25) in the engaged position. An aperture (26) that runs through the device (17) is visible when the retaining elements are in the engaged position and the indents (23a) of the locking tabs (23) align. A padlock or cable tie is placed through this aperture (26) to safely secure the device in the engaged position when it is inserted in a fuse holder (1). See FIG. 14C.

(21) In use, when placed in a fuse holder (1), the retaining elements (18a, 18b) interact with the metal clips (2) of the fuse holder (1) in the engaged position. The engagement occurs by means of the projections (22a, 22b, 22c) interlocking with the arms of the metal clip (2). Once the foot (22) is engaged with the metal clip (2) it can only disengage if it is slid away from the clip (2), in the direction along the base of the fuse holder (1). The foot (22) cannot be disengaged by pulling the retaining element (18) away from the base of the clip (2), in the direction toward the tip of the clip. The curvature of the clip (2) prevents this movement. Further, when in use in a fuse holder, as shown in FIG. 14C, the cylinder of the core body (24) is inserted into the metal clips (2) of the fuse holder (1). The cylinder expands the metal clips (2) slightly. This expansion further prevents the foot projections (22a, 22b, 22c) from disengaging with the metal clip (2) in the direction starting from the base, moving towards the tip of the clip (2).

(22) In use, the device (17) is inserted into and removed from the fuse holder (1) using fuse pullers (30) (see FIGS. 14A and 14B). The fuse pullers (30) grip the core body (24) at demarcated areas (28 a, 28 b, 28 c) where the core body (24) is configured to receive the fuse holder (1) (see FIG. 14B). The actuator tabs (20) of the retaining elements (18) are accessible at two of the demarcated areas (28 b, 28 c) as they protrude through the aperture (27). Accordingly, on gripping the device, the fuse pullers (30) exert pressure on the actuator tabs (20) of the retaining elements (18). The pressure causes the actuator tabs (20) to slide towards the centre of the cavity (25) within the core body (24) of the device (17). This inward sliding motion is assisted by the angled surface (20 a) of the actuator tabs (20). The movement of the actuator tabs (20) of the retaining elements (18 a, 18 b), compresses the spring (19) between the retaining elements (18 a, 18 b); the device is in the ‘released position’. The device (17) is then placed into the fuse holder (1) such that the cylinder core body (24) is inserted into the metal clips (2) of the fuse holder (1). When the device (17) is in place in the fuse holder (1) the fuse pullers (30) release the device, thereby removing the pressure exerted on the actuator tabs (20). This, in turn, allows the compressed spring (19) to expand, thereby urging the retaining elements (18 a, 18 b) away from each other, such that the feet projections (22 a, 22 b, 22 c) of the retaining elements (18 a, 18 b) interdigitate with the arms of the metal clip (2). The device is in the ‘engaged position’. The indents (23 a) in the locking tabs (23) align with the aperture (26) passing through the device (17). A padlock or a cable tie is passed through the aperture (26) to secure the device (17) in the fuse holder (1).

(23) The device (17) is manufactured by injection moulding. The device (17), specifically the core body (24) and cover (28), are made in two parts as shown in FIGS. 10A-C and 11A-C, respectively, and the retaining elements (18) are made separately. The retaining elements (18) and spring (19) are arranged inside the cavity (25) of the core body (24) and before the two parts are joined together to assemble the device (17).

(24) In a further aspect, the invention provides a safety system (16) for use in safely and securely isolating one or more subsidiary circuits. The circuit is isolated by removal of the cartridge fuse. The safety system (16) prevents the untimely re-insertion of a cartridge fuse into the fuse holder (1) so as to protect operatives working on the isolated circuit.

(25) FIG. 1 shows a safety system (16) comprising two retaining elements (4a, 4b) and a cover element (3). The retaining elements (4a, 4b) interact with the cover element (3) and with the metal clips (2) of the fuse holder (1).

(26) Each retaining element (4) comprises a tab (5), a stem region (6) and a foot (7). The foot comprises three projections (12a, 12b, 12c). (See also FIGS. 3A, 3B and 3C).

(27) The cover element (3) comprises four apertures: two apertures (8a, 8b) for receiving the retaining elements (4a, 4b) when the retaining elements (4a, 4b) are engaged with the metal clips (2) of the fuse holder (1); a central aperture (9) for receiving the retaining elements (4a, 4b) when the elements are adjacent to each other and not engaged with the fuse holder (1) (as shown in FIG. 6); and a locking aperture (10) for receiving a locking tab (11). (See also FIGS. 4A and 4B)

(28) When in use in a fuse holder, as shown in FIG. 1, the foot (7) of the retaining elements (4a, 4b) engages with the metal clip (2) of the fuse holder (1). The engagement occurs by means of the projections (12a, 12b, 12c) interlocking with the arms of the metal clip (2). Once the foot (7) is engaged with the metal clip (2) it can only disengage if it is slid away from the clip (2), in the direction along the base of the fuse holder (1). The foot (7) cannot be removed by pulling the retaining element (4) away from the base of the clip (2), in the direction toward the tip of the clip. The curvature of the clip (2) prevents this movement.

(29) The cover element (3) is placed over the retaining elements (4a, 4b) such that a tab (5) of a retaining element (4a, 4b) is received in an aperture (8a, 8b), respectively. The apertures (8a, 8b) are a specified distance apart so that when the cover element (3) is in contact with the retaining elements (4a, 4b) via the apertures (8a, 8b), the retaining elements (4a, 4b) are positioned such that the foot of each retaining element is engaged with the metal clip (2).

(30) FIGS. 2A and 2B show the safety system (16) of the invention as described above in relation to FIG. 1, when in use in a fuse holder (1). Additionally, the system (16) shown in FIG. 2 comprises a core body (12). The core body (12) comprises a slot (13) that runs through the core body from the underside to the upperside of the core body (12). The core body (12) also comprises a cylindrical element (14) that is connected to a platform element (15). There is a locking tab (11), which comprises a locking aperture, mounted on the platform element (15). (See also FIGS. 5A, 5B and 5C).

(31) When in use in a fuse holder, as shown in FIGS. 2A and 2B, the cylindrical element (14) of the core body (12) is inserted into the metal clips (2) of the fuse holder (1). The cylindrical element (14) expands the metal clips (2) slightly. This expansion further prevents the foot projections (12 a, 12 b, 12 c) from disengaging with the metal clip (2) in the direction starting from the base, moving towards the tip of the clip (2). The stem region (6) of the retaining elements (4 a, 4 b) is encompassed within the slot (13) of the core body (12). The locking tab (11) is protruding through the locking aperture (10) in the cover element. A padlock is attached (not shown in Figure) through the aperture on the locking tab, thereby securing the system (16) in the fuse holder (1).

(32) FIG. 6 shows the safety system (16), comprising the retaining elements (4a, 4b), the cover element (3) and the core body (12), when not in use. The retaining elements (4a, 4b) are held in the central aperture (9). The system (16) is in this configuration when it is inserted into and removed from a fuse holder (1) (see FIG. 7). The positioning of the retaining element s (4a,4b) avoids the foot (7) being caught up or broken in the metal clip (2) during insertion and removal. The system (16) can be inserted and removed using fuse pullers (not shown in the figures) that grip the core body (12) as they would a cartridge fuse, or manually inserted and removed into and out of the fuse holder by hand.

(33) The system (16) as shown in FIG. 6 is assembled by inserting the retaining elements (4a, 4b) into the slot (13) of the core body (12). The tab (5) of the retaining element (4) has a cuboid shape and can only be inserted into the slot (13) if the longest dimension of the tab (5) is aligned with the longest dimension of the slot (13). Once the tab (5) has been pushed through the slot (13), the retaining element (4) is rotated by 90° so that the tab (5) cannot pass back through the slot (13). The retaining elements (4a, 4b) may move back and forth along the length of the slot (13), i.e., from one end of the slot (13) to the other. The retaining elements (4a, 4b) are gathered next to each other in the centre of the slot (13). The cover element (3) is then introduced: it is placed onto the core body (12) such that the locking tab (11) lines up with the locking aperture (10). The retaining elements (4a, 4b) are aligned in the slot (13) so that they fit into the central aperture (9). The tabs (5) are oriented correctly to fit into the central aperture (9) after being rotated as described above. The tabs (5) and the aperture (9), and the locking tab (11) and the locking aperture (10), respectively, have a close fit so as to prevent unwanted movement between the elements of the system (16). During storage of the system (16), a padlock (18) may be passed though the locking aperture (16) to retain the elements of the system (16) together.

(34) As mentioned above, the system (16) is in the configuration shown in FIG. 6 when it is inserted into a fuse holder (1) (see FIG. 7). Once inserted, the system (16) is then engaged with the fuse holder (1). The cover (3) is removed and the retaining elements (4a, 4b) are can slide away from each other, along the slot (13), towards either end of the fuse holder (1). Before the retaining elements (4a, 4b) are moved, it is important to ensure that the foot (7) and the projections (12a, 12b, 12c) thereon are orientated to engage with the metal clip (2). That is, the projections (12a, 12b, 12c) should be facing the metal clip (2). Once the foot (7) and the projections (12a, 12b, 12c) on each retaining element (4a, 4b) have engaged with their respective metal clip (2), the cover (3) is reattached. Once again, the locking tab (11) lines up with the locking aperture (10). However, in this instance, the retaining elements (4a, 4b) align with individual apertures (8a, 8b). The addition of the cover (3) prevents any relative movement between the two retaining elements (4a, 4b) as they can no longer slide along the slot (13). Once the system (16) is assembled, a padlock can be passed through the security aperture (17). This serves to secure the cover (3) to the core body (12). Furthermore, as the retaining elements (4a, 4b) are engaged with the metal clips (2) and are immobilized in place by the core body (12) and cover (3), the locked system (16) cannot be removed from the fuse holder.