DK144289B - SAFETY LIST FOR MAINTENANCE OF NUMBER OF ELECTRIC FUSES - Google Patents

Description

(19) DENMARK (¾½

Ia & sss)

\ 0 (12) PUBLICATION WRITING (11) 144289 B

DIRECTORATE OF THE PATENT-OO TRADE MARKET

(21) Application No. 847/76 (51) Int.CI.3 H 01 H 85/20 (22) Filing date 27 · Feb. 1976 (24) Race day 27 · Feb. I976 (41) Aim. available Aug 29 1976 (44) Posted Feb 1 1982 (86) International Application No. ~ (86) International Filing Day - (85) Continuation Day - (62) Master Application No. -

(30) Priority Feb 28 1975 * 2508845, DE

(71) Applicant _SIEMENS AKTIENGESELLSCHAFT, Berlin and Munich, 8 IVJuenchen 2, DE.

(72) Inventor Wolfgang Schmidt, DE: Ewald Siteiner, DE.

(74) Clerk of the International Patent Office.

(54) Fuse list for retaining a number of electrical fuses.

BACKGROUND OF THE INVENTION 1. Field of the Invention This invention relates to a fuse strip for retaining a plurality of electrical fuses, preferably surge arresters, for securing circuits to electrical surges and / or overcurrents. a partially embedded contact path connected to said circuit in an insulating material carrier;

OQ

to be secured while the other electrode abuts against a U-shaped potential connected to 00 ground potential, which in the contact area in question is designed with a corresponding number of fuses d "number of tongues with contact parts, which in the case of disturbance short-circuit - utes the fuse in question.

*

ISLAND

Such fuse lists are often used in telecommunications distribution systems, in particular telephone transmission technology, and serve to link a fuse, e.g. a gas surge arrester of known type, to each working circuit in the plant or by multiple wires, e.g. to the a and b conductors by means of which fuse the current conductors in the circuits to be secured are applied to earth potential by the occurrence of a short-duration inductive overvoltage # If this overvoltage is of longer duration, however, the current caused will heat the overvoltage conductor exceedingly strong, which can eventually lead to its destruction.

In order to protect the surge arrester from destruction in such cases, from German publication specification No. 2,315,838 fuse lists, wherein a melting ring is held between an electrode on the surge arrester and a contact path connected to the circuits to be secured.

When heating the melt ring as a result of the aforementioned extremely strong heating of the surge arrester, the arrester is short-circuited by means of a contact device.

It has been found that, in the known construction, this contact device is relatively complicated and therefore does not allow for large-scale economic production. Thus, it is known to design part of the contact device as contact path containing platinum, the contact paths being connected to each other by means of interconnectors arranged at their ends and in this state enclosed in plastic in injection molding tools. Only after the injection molding process are the cross-connection pieces separated by separate tools to obtain separate contact paths.

The other part of the earth potential contacting device is formed by a substantially U-shaped and movable retaining member, the one leg of which has a plurality of tongues corresponding to the number of fuses, and at whose ends, deflected projections are arranged almost perpendicularly. The free ends of these projections will, in the event of disruptions through breakthroughs in the insulation material carrier, hang against abutments against the contact paths embedded in the carrier and thereby short-circuit the surge arrester. Since these projections have a smaller cross-section than those with connected tongues, more work steps are required for their manufacture.

The invention has for its object to design such a security list in such a way that it can be manufactured in a simple and economical manner as a mass article.

According to the invention, this task is solved by the substantially one leg of the retaining member extending parallel to the strip-shaped tongs having a recess which forms a locking connection with an elevation arranged on the insulating material carrier and that the strip-shaped single-shaped elements are formed. contact webs, after being placed in a cassette-like insert mold in a manner known per se, are insulated with material, preferably plastic, and in the region of the tongues of the retaining member has a U-shaped bend towards the contact ends forming tongue ends.

In forming the said second leg of the recess with a recess and of the insulating material carrier with an elevation, these parts can easily be connected to and detached from each other without the aid of tools, which is an advantage, for example, in the fitting with fuses. In this connection, an important factor for lowering the manufacture of the fuse strip according to the invention is that the contact paths are formed as individual identical elements which, after being placed in the cassette-like insert form, are covered with insulating material in a manner known per se. In the above-mentioned known fuse list, single elements are present only in the final state, and to achieve this state several working steps are required, which have a significant impact on the manufacturing costs. In the wrapping of still interconnected contact paths in the insulating material, there is the problem that undesirable shrinkage cracks occur in the curing insulating material, which in the known fuse list can only be partially prevented by a meander-shaped design of the individual contact paths in extension or providing additional cuts, thereby only achieving an extension in one direction in the plan's plan.

This design of the contact elements to coincide in a punch platinum requires, in addition to cuts in the insulating material carrier in the region of the two parallel rows, interconnecting pieces between the contact paths, separating these cross-connecting pieces after the insulation material curing by means of a special tool.

By designing a contact web as individual identical elements, which, after being placed in a cassette-like insert form, is shrouded with insulating material, shrinkage cracks in the insulating material can be easily avoided, while at the same time the two above-mentioned extra working steps lapse. It has been found that due to the shape identity of the contact paths, in addition to a cost reduction in manufacturing and storage, a sufficiently high stability of the insulation material carrier is obtained.

While the tongues of the known fuse strip for the contact formation are provided with additional contact fingers which have diminished cross-section and are formed integrally with the fuse strip, the fuse strip according to the invention serves the tongue ends which are substantially parallel to the retaining member for contact formation.

Fuse strips according to the invention are used in compactly constructed distribution systems and are interposed with a corresponding contact device with the longitudinal contact path ends. Therefore, in case of disturbance, closed contacts at the fuse list according to the invention can be recognized immediately by visual inspection.

The end of each contact path, which can be connected to the circuits to be secured, can be connected by means of a contact spring. having a trapezoidal cross-section, may be disposed in a longitudinal side of insulating material carrier is one in which there are two recesses extending longitudinally along the contact path ends of the insulating material carrier. With such recesses that e.g. may have a triangular or trapezoidal cross-section, fine metal particles which, upon repeated insertion or removal of the fuse strip, respectively, into or out of a distributor in a telephone transmission system may be deposited on the resin due to the wear between the contact paths and the contact springs, which may otherwise result in a undesirable electrical connection, be deposited only on the ribs limiting in the recesses of the insulating material carrier.

The invention will be explained in more detail below with reference to an embodiment of the drawing, in which fig. 1 is a perspective view of a fuse strip; FIG. 2 is a side view of this list, partially in section, and FIG. 3 is a sectional view from the list indicated by C in FIG. 2nd

The FIG. 1 and 2 serve to record ten surge arresters 1, hereinafter referred to as fuses. These fuses serve to electrically protect a and b wires for a maximum of five to a subscriber wiring arriving at a telephone exchange facility. On each of the fuses is a c 144289

ISLAND

electrode 3 over a melting 4 of a low melting point electrically conductive metal electrically connected to a metallic contact path 5, while the other electrode 2 abuts against a metal U-shaped holding member 6, one leg of which has one for the number of fuses a corresponding number of tongues 11, which holding means is associated with ground potential, e.g. over a grounding spring not shown at its bottom 7. The strip-shaped contact paths 5 are embedded in the insulating material carrier 9f material by an injection or die casting process, wherein the insulating material carrier has recesses 1o which serve to receive the surge arresters 1 and the melt rings 4 ·

In this connection, the contact paths 5 are designed so that, from the interior of the retaining member 6, they have a U-shaped bend 12 in the region of one tongue end 11 of the retaining member 6. The outer region 13 of each contact path 5 has a trapezoidal cross-section and ends in a long side 14 of the insulation material carrier 9 · The areas e 13 of the contact paths 5 are arranged in the longitudinal side 14 so that their outwardly facing surfaces and the edge 16 of the insulation material carrier 9 are in the same plane. By means of these outward facing surfaces of the contact paths 5, the a and b conductors are electrically connected over contact springs not shown here. In order to avoid electrical connection between the individual contact path ends 13 due to the metallic wear of the contact springs which occur to them upon repeated insertion or extraction of the fuse strip into or out of a distributor in a telephone switching system in the arrow shown by A or B respectively. direction, two recesses extending longitudinally along the contact paths 13 are arranged between two contact path ends 13. 15. As a result of these recesses 15 which e.g. may have a triangular or rectangular cross section, fine metal particles will only be deposited on the indentations limiting ribs in the insulation material carrier so that said contact springs cannot establish short circuits between the individual contact paths. The insertion or extraction of the fuse strip can be done in the direction of arrow A or B by means of a handle 17 · As the fuse strip in the distributor must be pushed forward to the insertion point past several threads, the long side 14 with the contact path ends for protection of thread is formed with smooth thread-friendly surfaces and the one in the insertion direction. The front end of this long side is shaped like a wedge 2o.

A molded connection between the insulating material carrier 9 and the U-shaped holding means 6 is obtained by means of a projection 18 arranged on the insulating carrier which engages an opening 19 of the

Claims (2)

6 The distance between the U-shaped region 12 of each contact path 5 and the tongue 11 of the U-shaped holding means is somewhat smaller than the thickness of the melting ring 4. In the case of overloads such as through prolonged surges and a The resultant current could lead to excessive heating of the surge arrester, this ring 4 melts and the circuits to be secured are connected across the holding device 6f's leg 11 with ground potential. Due to the design, the holding means 6 and the contact paths in this area, it can be immediately ascertained by means of a simple visual check whether there is open or closed ground contact. A fuse strip for retaining a plurality of electrical fuses, preferably surge arresters (1), for securing circuits to electrical surges and / or overcurrents, said fuse strip having a contact device between whose contact parts of the fuses (1) are held clamped, wherein an electrode ( 3) in each fuse (1) abuts against a partially embedded contact path (5) in a carrier (9) of insulating material, which is connected to the circuit to be secured, while the other electrode (2) abuts one by one. earth potential connected, U-shaped holding means (6), which in the contact area concerned is formed with a number of tongues (1) corresponding to the number of tongs (11) with contact parts, which in the event of a disturbance short-circuits the fuse concerned, characterized in that it the substantially one leg extending parallel to the holding member (6) having strip-shaped tongues (11), the second leg of the holding member (6) has a recess (19) which forms a locking connection with an elevation (18) arranged on the insulating material carrier (9), and that, as individual identical strip-shaped contact webs (5) formed after insertion in a cassette-like insert form, in a manner known per se, is covered with insulating material, preferably plastic, and in the region of the tongues (11) of the holding member (6) have a ϋ-shaped bend (12) towards the tongue ends (11) forming the contact parts.