GB2042273A

GB2042273A - Electric fuse holder for fuse cartridges

Info

Publication number: GB2042273A
Application number: GB8003251A
Authority: GB
Original assignee: LINDNER GmbH
Current assignee: LINDNER GmbH
Priority date: 1979-02-01
Filing date: 1980-01-31
Publication date: 1980-09-17
Also published as: FR2448220B1; FR2448220A1; DE2903826C2; IT8019525A0; ES488176A1; IT1129678B; DE2903826A1; BE881508A; NL182261C; NL182261B; GB2042273B; NL8000101A

Abstract

A switchable electric fuse holder includes in its housing (1) a rockable inner component (9) and a fuse carrier (19) Fig. 3 which can be inserted therein, the inner component having an insertion aperture (26) Fig. 2a (not shown) provided with a coding profile, preferably including coding grooves (27, 28) to ensure only a correspondingly coded fuse carrier (19) can be inserted therein. The fuse carriers (19) are capable of receiving any of a range of fuse cartridges (20), but each should only be loaded with a cartridge of the appropriate value. The rockable inner component (9) is rotated by a handle (21) extending from the carrier (19) and moves the cartridge 20 into switching engagement with spring contacts (15), (16) in the fuse holder housing (1). <IMAGE>

Description

SPECIFICATION Electric fuse holder for fuse cartridges The invention relates to an electric fuse holder of the kind in which the fuse cartridge is held in a holderwhich can be rocked between switched-on and switched-off positions.

Such a fuse holder is known from French Patent Specification 2 191 234. The fuse holder there described has disadvantages resulting from the fact that the fuse holder must be able to be fitted with fuse cartridges of any one of a range of different current ratings. These cartridges are held in a carrier which must be readily inserted into the rockable inner component of the fuse holder. Since, as a rule, fuse cartridges of different current ratings also have different external dimensions to assist in identification of the cartridge it is necessary with the known fuse holders to use for this purpose respective carriers with different inner dimensions which must be adapted to the outer dimensions of the fuse cartridges.However, all of these different carriers can then be readily inserted individually into the tiltable inner component of the fuse holder so that during assembly mistakes may easily occur, especially if fuses of various current ratings are to be mounted in adjacent fuse holders.

Furthermore, the cooperating contacts arranged on the inner component involve considerable material cost and do not have any electric shock-avoiding insulation with the result that careless holding of the inner component during fuse cartridge replacement can result in an electric shock being sustained by the operator. The assembly of these cooperating contacts on the inner component also requires additional assembly time. It is, moreover, necessary for the cooperating contact and the connecting terminal cooperating therewith to be formed of two parts.

Swiss Patent Specification 38 173 discloses the use of fusible cutouts for various current ratings and voltages whose cartridges cannot be interchanged.

The non-interchangeability of these fusible cutouts is achieved and safeguarded in that the cartridges are fitted with additional projections which are arranged in a certain way in relation to contact pins serving to ensure the electrical contact of the fuse cartridge elements. The method known from this earlier publications for safeguarding non interchangeability cannot be readily applied to insertion fuse holders with end contact caps, since with the latter there is no fixed reference characteristic such as the abovementioned contact pins.

It is an object of the present invention to provide an improved form of insertion fuse holder such that it may be used with a multiplicity of fuse cartridges with different properties, for instance, different current ratings, and response characteristics, and that a wide ranging non-interchangeability of the cartridges is nevertheless ensured.

Accordingly the present invention provides an electric fuse holder for a fuse cartridge, said holder having a housing, a rockable inner component with an aperture to receive a fuse carrier, and a fuse carrier adapted to hold a fuse cartridge and to be inserted into said inner component with a said fuse cartridge therein, wherein a range of carrier types is provided such that the inner dimensions of all the types of carrier are adapted to the outer dimensions of the respective fuse cartridge to be used and the carriers and the insertion apertures of the inner components have various profiles indicative of the various current ratings of the fuse cartridges for which they are intended, and wherein the carrier has an operating dolly to enable the inner component to be tilted between the switched-on and switched-off positions.

The advantages obtained by the present invention include the fact that it is no longer possible to insert fuse cartirdges of a higher current rating into a fuse mounting which is designed for a lower current rating.

Preferably, the carriers and inner components appropriate for the respective current ratings of the cartridges have, in the region where they overlap on insertion, ribs and grooves which vary in their arrangement and/or dimensions. This feature provides the special advantage that the ribs and grooves are also easily discernible by way of touch and this may possibly represent an aid for the fitter.

Advantageously, each said fuse carrier has a window for the fuse condition indicator of a fuse cartridge in the carrier. Thus, to ascertain the condition of the fuse cartridge, i.e. whether the fuse cartridge has blown, it is no longer necessary to remove the cartridge from the fuse mounting in order to examine the condition indicator.

Suitably, said housing includes electrical contact spring blades and said inner component has shaped bevels able cammingly to force apart the contact springs during the switching-on process, and said inner component further includes centrally disposed longitudinal slots through which tabs of said contact springs project in the fully home switched-on position to make electrical contact with a fuse cartridge held in said carrier.This results in snapping of the spring contacts into engagement with the end caps of the fuse cartridge as rocking of the inner component into its "fully home" switched-on position nears completion and thus, contact between the contact springs and the end contact caps of the fuse cartridge is reached very rapidly, even when the inner component is being rocked slowly, so that even when switching-on to a short circuit attaining the value of the surge rating of the fuse cartridge, there cannot, in practice, be any switch arcing.

It is moreover desirable to ensure that whilst maintaining a high switch loading, the number of components which are live when the inner component is open is reduced; that is to say, to achieve protection against electric shock when the fuse carrier is extracted, and to reduce the labour cost of assembly.

In orderthatthe present invention may be more readily understood the following description is given, merely by way of example, with reference to the accompanying drawing, in which: FIGURE 1 shows a cross-section through a fuse holder with an inserted carrier for the fuse cartridge; FIGURE 1a is a top plan view of the fuse holder of Figure 1, but without an inserted carrier; FIGURE 2 is a side view of the inner component which is tiltably mounted in the fuse holder; FIGURE 2a is a top view of the inner component shown in Figure 2.

FIGURES 2b and 2c illustrate in a simplified representation, alternative insertion openings for the Figure 2a embodiment of inner component for the fuse cartridge carrier where higher current ratings are to apply; FIGURE 3 is a side view of the carrier for the fuse cartridge which may be inserted into the inner component shown in Figures 2 and 2a; FIGURE 3a is a cross-section through the carrier of Figure 3, the plane of section being that indicated in Figure 3; and FIGURES 3b and 3c illustrate, in a simplified representation, the outer dimensions of the carrier for fuse cartridges of higher current ratings.

The fuse holder shown in Figures 1 and 2 consists of two dish-shaped casing components 1,2 which are joined to each other by rivets 3 to form a cylindrical housing. The U-shaped contact springs 4, 5 (Figure 1) are formed integrally with connecting lugs 6, 7 serving as connecting terminals, and are inserted into corresponding guide grooves of the casing components 1, 2. The rotary inner component 8 is rotatably mounted in the casing component 1, 2, by means of bosses 9, 10 and has V-shaped extensions 11, 12 in order to provide an insulating shield fqr the contact springs 4, 5 in both the switched-on and switched-off positions. As the inner component 8 is rotated or rocked into the switched-on position, the U-shaped contact springs 4, 5 are forced apart by means of the bevelled surfaces 13, 14 of the inner component 8.In the "fully home" switched-on position, the inward contact tabs 15, 16 on both sides of the U-shaped contact springs 4, 5 engage in lon gitudinal slots 17, 18 of the inner component 8 and make contact with the terminal contact caps of the fuse cartridge 20 which has been inserted into the inner component 8 and held in place by means of carrier 19 (Figure 3). The fuse cartridge 20 is, for the sake of clarity, shown by fine lines in the drawing.

For switching-on, that is to say for rocking the inner component by means of carrier 19, an operat ing force must be exerted which shortly before the "fully home" switched-on position is reached, suddenly recedes to a minimum so that instantaneous switching on is achieved. This reduction in value of the switch-operating force results from the camming engagement of the strip contacttabs 15, 16 and from the elasticity of the contact springs 4, 5, giving rise to a force assisting rocking and also ensuring that the tabs 15, 16 suddenly snap into engagement with the end contact caps of the cartridge 20.

In the drawing, the position of the inner compo nent8 with the inserted carrier 19, in the switched-on state, is given by dashed outlines. The width of the side slots 17, 18 in the inner component8 is dimen sioned in such a way that, in the "fully home" switched-on position, it is impossible, if the fuse car tridge 20 has been inadvertently omitted, for a test contact finger to touch the live contact spring. This also applies in the switched-off pos-tion since here the contact springs do not project into the longitudinal slots 17, 18; they are kept concealed and hence isolated from the interior of the carrier 19 by abutting the insulating walls of the inner component 8.

The carrier 19 has an operating dolly 21 serving as a handle for the switching-on or switching-off operation, respectively. Carrier 19 is hollowed out in the middle in order to accommodate the fuse cartridge 20. The latter is laterally inserted into the central recess 22 (Figure 3) and is secured against falling out, if carrier 19 is not inserted, by added tabs 23, 24., The central recess 22 is, of course, adapted to the respective value of the length and diameter of the insertable fuse cartridges and these values vary according to the current rating. To ascertain the state of the fuse cartridge (i.e. whether it has blown or not) where the fuse cartridge may possibly be provided with an interruption or tell-tale indicator, a window 25 is provided on the front face of carrier 19.Now in order to secure the fuse holder against use with fuse cartridges having the wrong current rating, thereare arranged on the inner component 8 insertion apertures 26 whose contours have grooves 27, 28 which are disposed in different ways. The carriers 19 have ribs 27', 28' corresponding thereto. The position of the grooves 27, 28 or ribs 27', 28' respectively, is indicative of the respective current rating of a fuse cartridge with which the carrier 19 is to be loaded. In the drawing, there are indicated current ratings 6A, 10A and 16A by way of example.From the exemplified embodiment of the fuse holder, with its inner component and its fuse cartridge carrier, it may be seen that it is impossible to insert a 10A fuse cartridge mounted in its correct carrier, into a fuse hol der which is designed for a current rating of 6A and has a corresponding inner component 8. By a further displacement of the ribs 27', 28' or grooves 27, 28 respectively, the non-interchangeability system of current ratings may be extended at will, to comprise other current ratings, or for fuse cartridges having different characteristics. Thus, even if fuse cartridges of various current ratings were to have the same outer and contact-forming dimensions-this is conceivable if fuse cartridges of different systems were to be used -a high measure of safety is afforded as regards non-interchangeability of current ratings in the case of a non-negligent operation - by the user.

Claims

1. An electric fuse holder for a fuse cartridge, said holder having a housing, a rockable inner component with an aperture to receive a fuse carrier, and a fuse carrier adapted to hold a fuse cartridge and to be inserted into said inner component with a said fuse cartridge therein, wherein a range of carrier types is provided such that the inner dimensions of all the types of carrier are adapted to the outer dimensions of the respective fuse cartridge to be used and the carriers and the insertion apertures of the inner components have various profiles indica tive of the various current ratings of the fuse cartridges for which they are intended, and wherein the carrier has an operating dolly to enable the inner component to be tilted between the switched-on and switched-off positions.

2. An electric fuse holder according to Claim 1, wherein the carriers and inner components appropriate for the respective current ratings of the fuse inserts have, in the region where they overlap on insertion, ribs and grooves which vary in their arrangement and/or dimensions.

3. An electric fuse holder according to Claim 1 or 2, wherein each said fuse carrier has a window for the fuse condition indicator of a fuse cartridge in the carrier.

4. An electric fuse holder according to any one of Claims 1 to 3, wherein said housing includes electrical contact spring blades and said inner component has shaped bevels able cammingly to force apart the contact springs during the switching-on process, and said inner component further includes centrally disposed longitudinal slots through which tabs of said contact springs project in the fully home switched-on position to make electrical contact with a fuse cartridge held in said carrier.

5. An electric fuse holder according to Claim 4, wherein said contact springs are in the switched-off position shielded from the interior of the fuse carrier by the insulating walls of said inner component.

6. An electric fuse holder according to Claim 4 or 5, wherein the contact springs are integrally formed with connecting lugs serving as connecting terminals.

7. An electric fuse holder constructed and adapted to operate substantially as hereinbefore described with reference to, and as illustrated in, the accompanying drawing.

8. The combination of an electric fuse holder according to any one of the preceding claims with spare said fuse carriers and spare said inner components appropriate to different fuse cartridge characteristics.