EP0017819B1 - On-load low tension switch with fuse - Google Patents

Abstract

1. A low-voltage load switch having a safety fuse (hereinafter referred to as a fuse switch), the fuse link (6) of which is arranged under spring force between a head contact, which is additionally covered by a lid (5) which can be in the form of a screw cap (3), and a base contact (4), of a fuse mounting, and in the current supply to which is arranged a load switch (1) which is coupled to the lid (5) and which suddenly releases the contacts by way of a mechanism (14) in the form of a toggle lever, and which, without the fuse link (6), is locked in an open position, wherein ventilating channels ensure that the temperature of the connecting terminals does not exceed a given operating temperature, characterised in that a) a movable magazine (7) made of high temperature-resistant material is raised from the base contact (4) of the fuse mounting in the direction of the imaginary line (10) connecting it to the head contact under spring force (spring 9) with the screw cap (3) and the fuse link (6) removed, and that this base contact (4) maintains the fuse link (6) under pressure with respect to the screw cap (3) which, from the point of view of exchanging the fuse, retains the direction of the connection line (10) and thereby produces the contact force on the head contact and the base contact (4) of the fuse link (6), b) that the load switch (1) comprises a contact arrangement (contact members 12, 13) which is such that the imaginary line (11) connecting its contacts is inclined to the line (10) connecting the head contact and the base contact (4) of the fuse mounting, and that the lid (5) laterally prevents grasping of the screw cap (3), c) and that from the contacts of the load switch (1), a ventilating channel (53) leads past the magazine (7).

Description

The invention relates to a low-voltage circuit breaker with fuse, hereinafter referred to as a fuse switch, as described in the preamble of the main claim.

The fuse link is arranged between an additional head contact covered by a flap, which can be designed as a screw cap, and a foot contact of the fuse base under spring force. A power switch coupled to the flap is arranged in the power supply of the fuse base and is locked in the open position when the fuse link is removed.

In such a known fuse switch (DE-A1-2 618 360) there is no movable magazine, but a rigid receptacle which forms a stop for an obliquely deflectable foot contact of the fuse base. An additional bracket is then required to lock the hinged lid. If the foot contact is set at an angle when switching and replacing the fuse link (DE-A1-2618360; DE-A1-2 722 279), this can lead to the fuse link becoming loose during frequent manual switching without changing the fuse link. Increased contact resistance and arcing can then endanger the device as a whole.

In the known fuse switch (DE-A1-2 618 360), an imaginary connecting line through the contacts of the circuit breaker in the switched-on state has approximately the same direction as the imaginary connecting line through the contacts of the fuse, consisting of the fuse base and fuse insert. The invention is based on the finding that, although it is desirable to arrange the contacts of the fuse in such a way that the connection line, seen via a replacement process of the fuse link, is not changed for the reasons described above, that the imaginary connection line is changed by the contacts of the load switch can be placed at an angle.

In another known fuse switch (DE-A-2 334 595), the contacts of the fuse are arranged in such a way that the connection line is retained when viewed through an exchange or switching operation, but this device lacks a spring which is the contact force of the Ensures security independently of an operator. In this known fuse switch, the screw cap of the fuse link can be actuated when the flap is closed, as a result of which the contacts are exposed to particular loads when switching slowly. The contact pressure between the fuse link and the foot contact of the device depends on how strongly an operator pulls the fuse link.

• Insbesondere muss Stromdiebstahl sowohl bei eingesetztem als auch bei herausgenommenem Sicherungseinsatz verhindert werden. Anderseits muss sowohl für den Bedienenden als auch für das Gerät besondere Sicherheit erzielt werden.

Fuse switches are intended to increase the safe operation of fuses by laypersons. You would also like to use fuse switches in distributors in the supply to the meter, i.e. in the uncounted current range of a system. For example, one thinks of using instead of a conventional main fuse. Previous meter backup fuses are usually arranged in sealable devices, whereby the fuse links may only be used and replaced by trained and authorized personnel. In order to enable operation by laypersons with counter backups, special requirements must be met:

• In particular, theft of electricity must be prevented both when the fuse link is inserted and when it is removed. On the other hand, special safety must be achieved for both the operator and the device.

In the case of screw locks, the contact pressure on the connection flaps of the fuse link is generally generated by screwing the screw cap into a threaded part, the so-called threaded eyeglass. The contact pressure therefore depends on the operator. Too little contact pressure leads to increased contact resistance and can damage the contact points after a long period of operation. Since meter backup fuses are only exchanged rarely, usually only after very long operating times, a sufficiently high contact pressure and a correspondingly low contact resistance with a predetermined value must be ensured.

In order to make contact only after an insulating cap has been locked, lugs and cutouts are provided in a known lower fuse part (DE-B2-2409238). The insulating cap, with the fuse insert inserted, is first inserted in the axial direction up to a stop and then guided into a latching position by movement perpendicular to the longitudinal axis. This represents an unusual movement sequence for the operators and, due to the tolerances of the latching means, a constant contact pressure is not guaranteed here either.

Fuses which can be switched off are known (DE-Al-2 642 223), in which the contact to the fuse link is made after insertion by a rotary movement in the manner of a toggle switch. Since tolerances must also be compensated for here, the contacts are designed to be resilient, which is why they can only carry weak currents.

The invention has for its object to develop a compact fuse switch in which the power loss of the fuse link can be derived on the one hand, the contact pressure is achieved independently of the operator and tolerances and that even when switching contacts under load neither when switching nor afterwards can burn in long-term operation.

The solution to the described problem lies in a circuit breaker with the characterizing features of claim 1. By Ma magazine that receives the fuse link, the foot contact is guided on the one hand in the direction of the axis of the fuse link and, on the other hand, the fuse link is shielded against switching gases of the circuit breaker. Because of the spring that acts on the magazine, the contact pressure is independent of the operator and of tolerances. As long as the spring acting on the magazine is harder than a contact pressure spring, which ensures the contact pressure in the load switch, this guiding property is retained.

The contact arrangement in the load switch, according to which the imaginary connecting line of the contacts is inclined to the connecting line of the head and foot contacts of the fuse base, results in a low device construction with a large switching path or stroke of the switching contacts. The flap closing on the side prevents the screw cap from being screwed onto the fuse link before the flap is actuated. This and because the contacts are suddenly released via a mechanism like a toggle lever, ensures reliable switching. The contacts of the circuit breaker can therefore not scorch.

In the case of a compact construction of the fuse switch, heat dissipation is made possible by the construction described, by leading a ventilation channel past the magazine from the contacts of the load switch. This can be the case with a narrow housing of the fuse switch below the magazine.

In the case of a fuse switch which, unlike the fuse switch according to the invention, cannot be switched under load, the connecting line through the contacts of a switch to the connecting line through the head and foot contact of the fuse link is inclined (DE-A1-2 445 262). Apart from the fact that the switch can only be connected upstream of the fuse link by means of appropriate external wiring, a flap and a magazine are missing, so that the foot contact itself is designed as a spring. This results in insufficient contact pressure for a load as a load switch. Since the spring action can also only be weak, a lever of the switch is provided with a nose under the fuse link in order to lift the fuse link up for replacement. Such a circuit breaker is not protected against being switched on again without an inserted fuse insert. In addition, it could be switched so slowly that the contacts could scorch while sliding off an inclined plane.

The fuse switch according to the invention, on the other hand, is designed as a load switch, which makes it possible to switch even under load and to replace the fuse safely.

The head contact of the fuse link can be arranged in a manner known per se (FR-A-1404511) in a screw cap made of a handle and threaded sleeve, in which a viewing window is permanently clamped between the handle of the screw cap and the threaded sleeve firmly connected to it. This further increases security against power theft.

It is favorable here to design the threaded sleeve for the viewing window into a bottle-neck-like approach which, after the fuse link has responded, receives the discarded indicator sheet. Advantageously, the handle of the screw cap forms grip ribs and rib-shaped depressions on its outer edge, which are drawn over rounded edges up to the front side close to the viewing window. As a result, the screw cap can also be screwed in and out more easily if it only protrudes slightly beyond the edge of the housing.

It is expedient to design the magazine from ceramic material, since ceramic, with high temperature resistance, has better heat dissipation than molding material or plastic.

The height of the handle of the screw cap is expediently matched to the stroke existing between the switch-on position and the switch-off position of the fuse base in such a way that it is always in a gap-like connection to a trough-shaped edge of the housing surrounding it.

If the load switch forms a contact arrangement from two parallel contact zones, the current load is divided.

A particularly space-saving design is achieved with a large stroke of the switch contacts in that the contacts of the circuit breaker are formed on the one hand by an end-turned extension of a foot contact of the fuse base designed as a rail and on the other hand by two adjacent swivel arms which are bent towards each other at their free end, whereby the swivel arms are hinged to the base of the connection terminal for the power supply. In their interior, they can each receive a contact pressure spring, which is supported on its other side against the housing of the fuse switch.

If the connection terminal for the power supply has a saddle roof shape in side view and a rectangular plan, you can clamp thick conductors under the saddle and thin conductors across the saddle line. Such a connection terminal can be used universally if its clamping piece is arranged so that it can be implemented.

• In Fig. 1 ist der Sicherungsschalter bei längsgeschnittenem Gehäuse dargestellt.
• In Fig. 2 ist der Sicherungsschalter nach Fig. 1 von rechts gesehen, jedoch bei geschlossenem Gehäuse, dargestellt.
• In Fig. 3 ist der Sicherungsschalter nach Fig. 1 im ausgeschaltetem Zustand und bei entferntem Sicherungseinsatz wiedergegeben.
• In Fig. 4 ist der Sicherungsschalter nach Fig. 1 von links gesehen, jedoch bei geschlossenem Gehäuse, wiedergegeben.
• In Fig. 5 ist der Sicherungsschalter nach Fig. 1, jedoch bei geschlossenem Gehäuse, von oben gesehen dargestellt.
• In Fig. 6 ist der Sicherungsschalter nach Fig. 3 nach einem Schnitt längs VI-VI wiedergegeben.
• In Fig. 7 ist eine Schraubkappe in Seitenansicht dargestellt.
• Fig. 8 gibt die Schraubkappe nach Fig. 7 im Längsschnitt wieder.
• In Fig. 9 ist die Aufsicht auf die Schraubkappe nach Fig. 7 dargestellt.

The safety switch according to the invention will be explained in more detail with reference to an exemplary embodiment shown schematically in the drawing:

• In Fig. 1 the fuse switch is shown with a longitudinally sectioned housing.
• In Fig. 2 the fuse switch according to Fig. 1 is seen from the right, but with the housing closed.
• In Fig. 3, the fuse switch of Fig. 1 is shown in the switched-off state and with the fuse link removed.
• In Fig. 4 the fuse switch according to Fig. 1 is seen from the left, but with the housing closed.
• 5, the fuse switch according to FIG. 1 is shown, but with the housing closed, seen from above.
• In Fig. 6 the fuse switch of Fig. 3 is shown after a section along VI-VI.
• In Fig. 7 a screw cap is shown in side view.
• Fig. 8 shows the screw cap of FIG. 7 in longitudinal section.
• FIG. 9 shows the top view of the screw cap according to FIG. 7.

1 contains a load switch 1 and a fuse 2. A fuse link can be arranged between a head contact covered by the screw cap 3 and a foot contact 4 of a fuse base. The head contact in the screw cap is additionally covered by a flap 5. In the open position of the flap 5, according to FIG. 3, it is locked against being switched on again when the fuse insert 6 is removed, since the magazine 7 engages behind a stop 8 according to FIG. 3 with a nose.

The foot contact 4 is raised in the direction of the imaginary connecting line 10 to the head contact under the action of the spring 9 by means of the magazine 7 made of high-temperature resistant material. The foot contact 4 can be firmly connected to the magazine 7.

The load switch 1 has such an arrangement of the contact pieces 12 and 13 that the imaginary connecting line 11 of its contact pieces is inclined to the connecting line 10 of the head and foot contact of the fuse base. The flap 5 closes laterally and prevents access to the screw cap 3. The contact pieces 12 and 13 are suddenly released via a mechanism 14 in the manner of a toggle lever, in particular when switched on. In the exemplary embodiment, the toggle lever is essentially formed by two flap limbs 15 to be presented one behind the other in the plane of the drawing and two switching limbs 16. The flap legs are articulated on the axis 18. The switching legs 16 are each connected in an articulated manner to connecting legs 19, which act on two pivot arms 21 about the fixed axis 20. In the exemplary embodiment, the load switch 1 has a contact arrangement comprising two parallel contact zones, one of which can be seen in the drawing, namely that with the contact pieces 12 and 13.

The contact pieces of the circuit breaker are formed, on the one hand, by a terminally bent extension of the foot contact 4, which is designed as a rail, of the securing base, and, on the other hand, by the two adjacent pivot arms 21, which are bent towards one another at their free end. The swivel arms 21 are articulated on the base 22 of the connection terminal 23 for the power supply. In their interior, they each hold a contact pressure spring 24, which is supported on its other side against the housing 25.

The connection terminal 23 provided for the power supply is of a saddle roof shape in the side view according to FIG. 2 and is rectangular in plan. Under the saddle you can clamp thick conductors and thin conductors across the saddle, i.e. in the plane of the drawing according to FIG. 2. By appropriately shaping the housing, the clamping piece of the connection terminal can be implemented in the connection level by 90 °.

The helical spring 26 with extended and fork-shaped ends on the one hand lifts the switching leg 16 and thus holds the flap 5 in the closed rest position. On the other hand, the helical spring 26 causes a contact pressure between the legs of the base 22 of the connecting terminal 23 and the swivel arms 21. The base 22 of the connecting terminal and the swivel arms 21 are made of electrically conductive material, while the hinged legs 15 and switching legs 16 are made of insulating material. The contact pressure between the contact pieces 12 and 13 of the contact arrangement of the circuit breaker is ensured in each case by the contact pressure spring 24 designed as a compression spring.

If you open the flap 5 with the fuse link 6 screwed in, the position in FIG. 3 is reached in the load switch. In contrast, the magazine 7 and the contact pressure spring 4 initially retain their position according to FIG. 1. If one unscrews the screw cap 3 by means of its handle 30 with its threaded sleeve 31 from the threaded eyeglass 32, the fuse link 6 is raised under the action of the spring 9. When the screw cap is removed, the fuse link can be removed from the screw cap. The threaded eyeglass 32 is fixedly connected to the outgoing terminal 33 for the current outlet.

When the fuse link is screwed in, the current is conducted from the connecting terminal 23 via the swivel arms 21 to the foot contact 4 through the fuse link to the head contact in the screw cap via the threaded sleeve 31 to the threaded eyeglass 32 and from there to the outgoing terminal 33.

When the flap 5 is open, the load switch is open, as can be seen in principle from FIG. 3. If you remove the fuse link 6 from the magazine 7, it is raised until it engages behind the edge 8 of a flap 5 of the flap 5 and the flap 5 is thereby locked against being switched on again until a fuse link is screwed in. When a fuse link is screwed in, the magazine 7 is moved downward from the position shown in FIG. To the position shown in FIG. 1. The action of the spring 9 ensures sufficient contact pressure with the fuse link. The magazine 7 of the fuse base can accommodate dowels in the usual way to ensure that only fuse links of a certain nominal current can be used.

The housing 25 can be formed from two similar shells 40, as can be seen from FIGS. 2 and 4. The housing shells can are held together by rivets 41. The flap 5 is articulated on the fixed axis 18. The movable axis 43 forms the knee of the toggle lever for the load switch.

When the safety switch is switched on after a fuse link has been inserted, a molded nose 50 according to FIG. 3 lies against the flank 51 of the flap leg 15 after a short free travel and lifts the axis 43 about the stationary axis 18 and out of the knee position, whereby the switching legs 16 raise the axis 52 and pivot the pivot arms 21, so that the contacts are closed under the action of the contact pressure springs 24 of the circuit breaker.

A ventilation channel 53 leads past the magazine 7 from the contact pieces of the load switch 1. In the exemplary embodiment, it is connected to the outside air via a ventilation slot 54. The structure described enables a compact, low fuse switch that can be snapped onto device mounting rails like other installation devices.

For this purpose, the housing has lugs 55 and 56, the lug 56 being a sprung sheet metal part, a so-called slide.

The screw cap 3 according to FIG. 7 has a handle 30 and a threaded sleeve 31. The handle 30 of the screw cap forms grip ribs 60 and rib-shaped depressions 61 on its outer edge, which are drawn over rounded edges 62 up to the front side close to the viewing window 63 according to FIG. 8. This makes the screw cap easy to grip and operate.

The inspection window 63 according to FIG. 8 can be used to check whether the fuse link has responded and should therefore be replaced.

The lens 63 is clamped between the handle 30 of the screw cap and the threaded sleeve 31 firmly connected thereto. If the threaded sleeve 31 to the viewing window 63 forms a bottle neck-like approach according to FIG. 8, after the fuse link has responded, the dropped indicator sheet can be reliably accommodated. This ensures a safe display and prevents the indicator sheet from falling into the fuse switch when it is replaced. The flanks 64 of the bottle neck-like narrowing of the threaded sleeve 31 form the head contact of the fuse.

Claims (8)

1. A low-voltage load switch having a safety fuse (hereinafter referred to as a fuse switch), the fuse link (6) of which is arranged under spring force between a head contact, which is additionally covered by a lid (5) which can be in the form of a screw cap (3), and a base contact (4), of a fuse mounting, and in the current supply to which is arranged a load switch (1) which is coupled to the lid (5) and which suddenly releases the contacts by way of a mechanism (14) in the form of a toggle lever, and which, without the fuse link (6), is locked in an open position, wherein ventilating channels ensure that the temperature of the connecting terminals does not exceed a given operating temperature, characterised in that

a) a movable magazine (7) made of high temperature-resistant material is raised from the base contact (4) of the fuse mounting in the direction of the imaginary line (10) connecting it to the head contact under spring force (spring 9) with the screw cap (3) and the fuse link (6) removed, and that this base contact (4) maintains the fuse link (6) under pressure with respect to the screw cap (3) which, from the point of view of exchanging the fuse, retains the direction of the connection line (10) and thereby produces the contact force on the head contact and the base contact (4) of the fuse link (6),

b) that the load switch (1) comprises a contact arrangement (contact members 12, 13) which is such that the imaginary line (11) connecting its contacts is inclined to the line (10) connecting the head contact and the base contact (4) of the fuse mounting, and that the lid (5) laterally prevents grasping of the screw cap (3),

c) and that from the contacts of the load switch (1), a ventilating channel (53) leads past the magazine (7).

2. A fuse switch as claimed in Claim 1, the head contact of the fuse mounting of which is arranged in a screw cap (3) comprising a hand grip (3) and a threaded sleeve (31), in which an observation plate (63) is immovably clamped between the hand grip (30) of the screw cap (3) and the threaded sleeve (31) which is fixedly connected thereto, characterised in that the threaded sleeve (31) is formed with an extension, in the form of a bottle neck, to the observation plate (63), (Fig. 8).

3. A fuse switch as claimed in Claim 2, characterised in that, at its outer rim, the hand grip (30) of the screw cap (3) is formed with gripping ribs (60) and rib-shaped recesses (61) which extend over rounded edges (62) into the end face close to the observation plate (63).

4. A fuse switch as claimed in Claim 1, characterised in that the magazine (7) is made of ceramic material.

5. A fuse switch as claimed in one of Claims 1 to 4, characterised in that the hand grip (30) of the screw cap (3) is so adapted in respect of its height to the distance between the closed and open positions of the fuse mounting that it always closely adjoins a surrounding, trough-shaped edge (70) of the housing.

6. A fuse switch as claimed in one of Claims 1 to 5, characterised in that the load switch (1) forms a contact arrangement made up of two parallel contact zones (Fig. 6).

7. A fuse switch as claimed in Claim 6, characterised in that the contacts of the load switch (1) are on the one hand formed by an extension, bent at its end, of a bar-formed base contact (4), of the fuse mounting, and on the other hand by two adjacent pivot arms (21) which at their free ends are bent towards one another, the pivot arms (21) being coupled to the base (22) of the connection terminal (23) for the current supply, and each accomodating within it a contact compression spring (24) which at its free end bears against the housing (25).

8. A fuse switch as claimed in one of Claims 2 to 7, wherein at least the connection terminal (23) provided for current supply is saddle roof-shaped in side view and rectangular in plan view, characterised in that the clamping portion of the connection terminal (23) is exchangeably arranged.

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