EP0017815B1 - On-load low tension switch with fuse - Google Patents

Abstract

1. A low voltage load switch possessing a cut-out device hereinafter referred to as a safety switch, whose fuse insert (4) is housed in an accommodating chamber which consists of a hinge-operated magazine (1) which can be locked in the lower position of its lift path, the current supply of which contains a load switch (13) which is automatically manually operated when the fuse insert (4) is exchanged, characterised in that the load switch (13) of head contact (5) and base contact (6) for the fuse insert (4) possesses special contacts (14, 15), where the base contact (6) of the accommodated chamber is rigidly connected to the switching contact (14) of the load switch (13).

Description

The invention relates to a low-voltage circuit breaker with fuse, hereinafter referred to as a fuse switch, the fuse link of which is arranged in a receptacle formed as a collapsible magazine which can be locked in its lower position within its stroke, and in the power supply of which a load switch which is forcibly actuated by hand when the fuse link is replaced is arranged. Such a circuit breaker is known in principle, although not with a load switch in today's sense (FR-A-20 63 804).

The forced actuation of a switch in the power supply to the fuse link and the magazine only give access to the fuse link when the fuse link is de-energized. Since in the known fuse switch (FR-A-20 63 804) the contacts of the switch are formed on the one hand by those of the fuse link and on the other hand by spring clips on a housing base, which can reach through the magazine window to the contacts of the fuse link, such a switch is mechanical sensitive. Such a design also does not tolerate large operating currents, as are required today, and the contact resistance and the current interruption depend on the handling by an operator.

A switchable fuse is known (US-A-20 18 476), according to which a wide, flat housing accommodates a slide, on which a fuse link can be inserted, and can be covered over a large area by a cover. The otherwise open slide has contact tabs which engage in one position with knife contacts of the housing base, the slide being offset from contact engagement laterally to this. Since the cover is attached to the slide, it can first be moved laterally into the off position, after which the cover can be opened. However, this process is not necessarily ensured, since the lid can also be opened without having to move it laterally. Depending on the cover structure, it may be that the contacts of the slide may be disengaged, but the general disadvantage remains that this contact separation is unreliable and that the contact resistance in the intermediate area depends on the operator and his quick or hesitant action. This can result in a dangerous arc and inadmissible heating. Such a switch does not allow safe operation under load and it has no magazine in the sense described above.

In a known fuse switch without magazine (DE-B-23 34 595), the fuse link is covered by a screw cap and additionally by a flap which has to be folded up before actuating the screw cap and thereby switches off the load switch in the power supply via a coupling. When the fuse link is removed, the flap must be locked in the open position to prevent the fuse switch from being switched on without the fuse link, as otherwise theft of electricity would be possible.

• Insbesondere muß Stromdiebstahl sowohl bei eingesetztem als auch bei herausgenommenem Sicherungseinsatz verhindert werden. Andererseits 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 sealed facilities, 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, power theft 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 a known circuit breaker, the area of use for the fuse link is covered by a flap which closes fully at the edge (DE-A-11 41 700). However, locking is also required here.

In order to make contact only after an insulating cap has been locked, lugs and cutouts are provided in a known lower securing part (DE-B-24 09 238). 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 not only represents an unusual sequence of movements for the operator, but switching under load is not harmless: since the switch contact is formed by the foot cap of the fuse link and a foot contact of the fuse base, the thin contact cap of the fuse link can be damaged when operating under load. This device is therefore not suitable for switching under load.

Fuses which can be switched off are known (DE-A-26 42 223) in which the contact for securing use after insertion is produced by a rotary movement in the manner of a toggle switch. Since tolerances have to be compensated for, the contacts are designed to be resilient, which is why they can only carry weak currents.

In another known fuse switch with flap (DE-A-26 18 360) a foot contact is inclined when switching and replacing the fuse link. Another known switch fuse works in a similar way (DE-A-27 22 279). In the event of frequent manual switching without having to replace the fuse link, inclined lifting foot contacts can lead to the fuse link becoming loose.

The invention has for its object to develop a circuit breaker with a magazine and yet operational and handling safe load switch that is safe against power theft. The solution to the described problem is that the load switch of head and foot contact for the fuse link has separate contacts, the foot contact of the receiving space being rigidly connected to the switch contact of the load switch.

Such a circuit breaker allows the load switch to be made stable and does not endanger the contacts of the fuse link, which are sensitive to an arc. The fixed connection between two contact points is known in an electrical switching device belonging to the genus of circuit breakers (CH-A-43 16 61). In order to expose the contact elements to an increased contact force in the closed position when current is passed, two legs which are practically parallel in the closed position and are electrically connected in series at adjacent ends by a bridging element movable in the switching plane are formed, one of which is connected to a connecting terminal and the other leg cooperates with the counter contact. This connection is not rigid and such a switch works without a magazine. This switchgear cannot accommodate a fuse link either.

Since the magazine in the fuse switch according to the invention completely encloses the receiving space for the fuse link, there is no access either when the fuse link is inserted or when the fuse link is removed. This fuse switch therefore fully protects an operator and, on the other hand, is secure against power theft. Therefore, a lock against being switched on again without a fuse insert can be omitted.

However, there is also no need for the usual screw cap, which is why operation is simplified. Since a scrub cap is missing, it cannot loosen when switching, which is why this safety switch is not susceptible to failure.

If the head contact is arranged in one folding part of the magazine and the foot contact in the other folding part, the fuse link can be exchanged particularly easily.

The contact pressure becomes independent of tolerance when an energy accumulator acts on the foot contact in the direction of the imaginary axis of the fuse link.

• In Figur 1 ist der Sicherungsschalter bei aufgeklapptem Magazin und eingelegtem Sicherungseinsatz im wesentlichen im Längsschnitt wiedergegeben. Dieser Zustant entspricht der Ausschaltstellung.
• In Figur 2 ist der Sicherungsschalter nach Figur 1 bei eingerastetem Magazin, also in der Einschaltstellung dargestellt.

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

• In Figure 1, the safety switch is shown essentially in longitudinal section with the magazine open and the fuse insert inserted. This state corresponds to the switch-off position.
• FIG. 2 shows the safety switch according to FIG. 1 with the magazine engaged, that is to say in the switched-on position.

The fuse switch according to FIG. 1 forms a receptacle for a fuse link 4 in a collapsible magazine 1 with the folding parts 2 and 3. The head contact 5 and foot contact 6 of the magazine represent the contacts of a fuse base. The head contact 5 is via a sheet metal part with a movable current conductor 8 connected to an outgoing terminal 9. The head contact 5 is arranged in the folding part 2 of the magazine 1 and the foot contact 6 in the other folding part 3. In the exemplary embodiment, a force accumulator 10 acts on the foot contact 6 in the direction of the imaginary axis 11 of the fuse link 4.

The folding parts 2 and 3 are connected by a hinge 12, the axis of which is arranged laterally to the receiving space and perpendicular to the imaginary axis 11 of the fuse link 4.

The load switch 13 has separate contacts from the contacts of the receiving space, foot contact 6 and head contact 5 with the contact pieces 14 and 15. The foot contact 6 of the receiving space is rigidly connected to the switching contact with the contact piece 14.

In the exemplary embodiment, 13 baffle plates 16 are arranged next to the contacts of the circuit breaker. An electrically conductive connection leads from the fixed contact to the contact piece 15 to the connecting terminal 17, to which the mains connection is to be made. A contact spring 18 ensures consistently good contact pressure.

The load switch can be accommodated in a protective insulating housing. The magazine with the folding parts 2 and 3 can be sealed in the closed position, so that it can be used universally. The device can be snapped onto mounting rails 19 in the usual manner.

A fitting element, which ensures the unmistakability for a melt insert of suitable nominal current strength in the usual way held in the exemplary embodiment by the spring clip 20. This can be designed such that it also covers a passage of the foot contact 6 through the magazine 1 to the outside.

If you swivel the folding part 3 up about the axis 12 to the folding part 2, the head contact 5 slides with a beveled end face 21 onto the head contact of the fuse link 4. The compression spring serving as energy store 10 is tensioned so that the appropriate contact pressure is ensured regardless of housing tolerances. The closed magazine 2 can then be pressed in in a manner known per se around the switch-on position according to FIG. 2 in the direction of the axis 11 of the fuse link 4. By pressing again, the magazine 1 is released again and raised to the extent that the grip edge of the magazine 1 can be grasped. Its sloping flanks 22 also serve as a support when the folding part 3 is opened. When the magazine 1 is locked in its lower position of the stroke, the edge of the magazine is covered by the housing edge 23 according to FIG.

If the circuit breaker is used in a conventional distribution, the exclusion terminal 17 and high output terminal 9 are shielded from the outside by a conventional cover 25.

Claims (3)

1. A low voltage load switch possessing a cut-out device hereinafter referred to as a safety switch, whose fuse insert (4) is housed in an accommodating chamber which consists of a hinge-operated magazine (1) which can be locked in the lower position of its lift path, the current supply of which contains a load switch (13) which is automatically manually operated when the fuse insert (4) is exchanged, characterised in that the load switch (13) of head contact (5) and base contact (6) for the fuse insert (4) possesses special contacts (14, 15), where the base contact (6) of the accommodated chamber is rigidly connected to the switching contact (14) of the load switch (13).

2. A safety switch as claimed in Claim 1, characterized in that the head contact (5) is accommodated in one lid component (2) of the magazine (1) whereas the base contact (6) is accommodated in the other lid component (3).

3. A safety switch as claimed in one of Claims 1 and 2, characterised in that an energy store (10) acts upon the base contact (6) in the direction of the imaginary axis (11) of the fuse insert (4).

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