GB2176664A

GB2176664A - Explosion-protected single- or multi-pole low-voltage HBC fuse

Info

Publication number: GB2176664A
Application number: GB08612016A
Authority: GB
Inventors: Karl Faber; Gerhard Schwarz
Original assignee: Brown Boveri und Cie AG Germany; BBC Brown Boveri France SA
Current assignee: BBC Brown Boveri AG Germany; BBC Brown Boveri France SA
Priority date: 1985-06-13
Filing date: 1986-05-16
Publication date: 1986-12-31
Also published as: DE3521154A1; DE3521154C2; FR2583588B1; GB8612016D0; FR2583588A1; GB2176664B

Abstract

In an enclosed, crush-proof explosion-protected low-voltage HBC fuse, a microswitch (35) is disposed. to whose actuating member (36) is secured a transverse member (37) which covers the indicating pins (33) of the low-voltage HBC fuse elements (32) and is moved by the latter in the direction of actuating the microswitch. In this way a signal is produced which indicates that one of the low-voltage HBC fuse elements (32) has broken the circuit. The fuse elements are enclosed in a two-part housing (10), (11) having partition walls (40) defining spacers for the individual fuse elements. <IMAGE>

Description

SPECIFICATION Explosion-protected single- or multi-pole low-voltage HBC fuse The invention relates to a single- or multi-pole explosion-protected low-voltage high-breakingcapacity fuse.

Fuses of this type are not normally accessible from the outside, so that it is not possible to ascertain whether the individual fuse or the individual fuse element has blown.

It is an object of the invention to provide an explosion-protected low-voltage HBC fuse, in which the assembly is simplified and an indication is provided as to whether the low-voltage HBC fuse has blown.

Accordingly, the invention provides an explosion-protected single- or multi-pole low-voltage high-breaking-capacity fuse, the low-voltage HBC fuse element(s) being inserted in an explosion-protected and crush-proof casing which comprises a first casing part and a second casing part, there being partition walls, which separate spaces corresponding to the number of poles and used for receiving the low-voltage HBC fuse element(s), provided on one casing part, connecting lugs which lead to the low-voltage HBC fuse element(s) emerging from the first casing part in a crush-proof manner.

By virtue of the fact that a microswitch, which may be actuable by the tripping or indicating pins of the low-voltage HBC fuse elements by way of the cross member, may be fitted in the interior of the crush-proof casing, a signal from the microswitch can indicate whether a low-voltage HBC fuse element has blown and can be transmitted to the outside in a simple manner. In this connection the cross member may be secured to the actuating member of the microswitch and may be arranged in the interior of the crush-proof casing in such a way that even if only one of the two outer low-voltage HBC fuse elements blows, i.e. if the tripping pin of that element moves, the microswitch is actuated.

The cross member may advantageously be constructed in the manner of a plate and may be provided on its side opposite the indicating pins with a recess which is used for holding the actuating member-constructed in the manner of a leaf spring of the microswotch.

This can prevent the cross member from pivoting about the fastening point on the actuating member when one of the two outer lowvoltage HBC fuse elements blows, but rather the cross members are then displaced transversely to themselves. In this connection the fastening can be effected in such a way that the recess may be formed by two opposite L-shaped formations which laterally embrace the actuating member formed in the manner of a leaf spring.

A fuse embodying the invention is hereinafter described, by way of example, with reference to the accompanying drawings.

Figure 1 is a view inside a low-voltage HBC fuse, with the cover opened; Figure 2 is a sectional view along the section line ll-ll of Fig. 1; and Figure 3 is a sectional view along the section line Ill-Ill of Fig. 2.

Referring to the drawings, an explosion-protected casing comprises a lower (in use) casing part 10 and an upper (in use) casing part 11, which are connected together by means of screw connections 12 (Fig. 1). The lower casing part 10 comprises a lateral casing wall 14, at the free end of which is provided a stop surface 15 of the casing cover 11. A circular flange edge 16, which is surrounded by the casing wall 14, is integrally formed on the upper casing part or on the cover 11, the annular contact surface between the two forming an air gap 17.

The lower casing part 10 is provided with conductor bars 18 and 19 which emerge through the side wall of the lower casing part 10 in a crush-proof manner and terminate in the outer region in connecting lugs 20 and 21, to which connexion lines can be joined by means of screws 22 and 23.

L-shaped connexion contacts 24 and 25 are secured to the inner end of the conductor bars 18 and 19 by means of screws 26 and 27. The said connexion contacts 24 and 25 are formed in a manner known per se on their arms 28 and 29 with the conventional contact shapes extending at right angles to the conductor bars 18 and 19, as generally customary for receiving the contact blades of lowvoltage HBC fuse elements. Contact blades of one low-voltage HBC fuse element 32 in each case are inserted into the said connexion contacts 24 and 25 on the arms 28 and 29, so that a current can flow from the connecting lug 20 by way of the connexion contact 24 and the contact blades 30 and 31 to the connecting lug 21.

Each low-voltage HBC fuse element 32 comprises in known manner an indicating pin 33 which springs out when the fuse element 32 is blown, vide position 33' shown in broken lines. In this connexion the problem is that in the case of low-voltage HBC fuse elements enclosed in a crush-proof manner the position of the indicating pin or pins cannot be observed from the outside. A microswitch 35, the actuating spring 36 of which is connected to a transverse member or traverse 37, is therefore secured to a casing projection 34 in the interior of the lower casing part.The con nexion between the actuating element 36 and the transverse member 37 is such as to prevent the transverse member from rotating about any point, and in particular about the fastening point formed by the transverse member, the microswitch and the actuating spring, but rather the transverse member is always moved by the indicating pins in the direction of actuating the microswitch 35. The transverse member 37 is therefore provided on the side facing the actuating spring 36 with mutually opposite guide grooves 37a which engage around the lateral edges of the actuating spring 36 and are thus used for the parallel guidance of the transverse member.

Partition walls 40 are provided in the lower casing part and they separate altogether three spaces 41, 42 and 43, in which are disposed the individual fuse elements 32.

These partition walls 40 can be integrally formed on the lower casing part 10 or they can be inserted as separate parts into corresponding depressions 46 (as shown). Partition walls 44 and 45, which increase the air and creep gaps between two adjacent connexion points, are likewise provided between the individual connecting lugs 20 and 21 with their screw terminals 22 and 23.

Claims

1. An explosion-protected single- or multipole low-voltage high-breaking-capacity fuse, the low-voltage HBC fuse element(s) being inserted in an explosion-protected and crushproof casing which comprises a first casing part and a second casing part, there being partition walls, which separate spaces corresponding to the number of poles and used for receiving the low-voltage HBC fuse element(s), provided on one casing part, connecting lugs which lead to the low-voltage HBC fuse element(s) emerging from the first casing part in a crush-proof manner.

2. A low-voltage HBC fuse according to Claim 1, in which the partition walls are integrally formed on the first casing part.

3. A low-voltage HBC fuse according to Claim 1, in which the partition walls are inserted as separate parts into depressions in the lower casing part and are held therein.

4. A low-voltage HBC fuse according to any one of the preceding claims, in which a control element, which is actuable by the indicating pin of an least one low-voltage HBC fuse element, is disposed in the casing.

5. A low-voltage HBC fuse according to Claim 4, in which a transverse member, which is connected to the actuating member of the control element and covers the indicating pins and which is displaceable by at least one indicating pin in the direction of actuating the actuating member of the control element, is provided in the region of the indicating pins transversely to the low-voltage HBC fuse elements.

6. A low-voltage HBC fuse according to Claim 4 or 5, in which the control emement is a microswitch.

7. A low-voltage HBC fuse according to Claim 6, in which the actuating member of the microswitch is a leaf spring which is guided rotationally rigidly in recesses in the transverse member and is secured therein.

8. An explosion-protected single- or multipole low-voltage, high-breaking-capacity fuse, substantially as hereinbefore described with reference to the accompanying drawings.