Electricity: circuit makers and breakers – Interlocking
Reexamination Certificate
1999-12-21
2001-05-01
Scott, J. R. (Department: 2832)
Electricity: circuit makers and breakers
Interlocking
C200S050120, C200S050210, C200S050330
Reexamination Certificate
active
06225581
ABSTRACT:
BACKGROUND OF THE INVENTION
The invention relates to an installation comprising an electrical switchgear apparatus and a movement transmission cable, designed to interlock the apparatus with an external mechanism. More specifically, the invention relates to a device for fixing a kinematic transmission cable with respect to an electrical switchgear apparatus.
Sheathed cables are commonly used to perform interlocks between two switchgear apparatuses such as circuit breakers, as illustrated by the document U.S. Pat. No. 5,726,401, or between a switchgear apparatus and an external device, for example between a circuit breaker and the access door to an electrical cabinet, as illustrated by the document U.S. Pat. No. 4,405,844, or to achieve mechanical remote controls, as illustrated by the document EP-A-0,183,931. These cables conventionally comprise a flexible external sheath in which a core can slide. In addition to its mechanical protection function, the flexible sheath provides the advantage of more or less keeping its shape once fixed, in spite of the internal sliding of the cable core, and allows a great freedom of positioning. One advantage of sheathed cables over other kinematic transmission devices such as rods or belts lies in the possibility of adapting their length and shape on site, when fitting is performed, which leaves a greater freedom of relative positioning of the apparatuses to be connected.
To fit a sheathed kinematic transmission cable between two movable means of an electrical installation, it is necessary to secure a first end section of the sheath with respect to a fixed element of the installation close to the first movable means to be connected, to secure the other end section of the sheath with respect to a fixed element of the installation close to the second movable means to be connected, and to secure each of the two ends of the core with respect to one of the movable means to be connected, the order of the operations being able to vary according to the installation technique used.
Usually, assembly requires one or more tightening operations due to the fact that fixing is performed by means of threaded rods and nuts, as shown in particular by the document U.S. Pat. No. 5,726,401 already referred to above. The assembly operation is therefore relatively long and tedious. As electrical switchgear apparatuses are often confined in frames or cabinets, the extremely limited access space available around the movable means to be connected makes assembly even more delicate.
SUMMARY OF THE INVENTION
The object of the invention is therefore to facilitate assembly of a kinematic transmission by sheathed cable between various elements of an installation comprising at least one electrical switchgear apparatus, without increasing the overall dimensions of the installation. Its object is also to make this assembly quicker and to enable assembly to be performed in spite of a small access volume.
These objects are achieved by means of an installation comprising at least one electrical switchgear apparatus and a kinematic transmission cable designed to interlock a movable means of the electrical switchgear apparatus with a mechanism external to the apparatus, the electrical switchgear apparatus comprising a frame, the kinematic transmission cable comprising a flexible sheath and a core able to slide in the sheath, the flexible sheath comprising an end section constituting a first part of the cable fixed with respect to the frame of the electrical switchgear apparatus by a first fixing means, the core comprising an end section external to the sheath constituting a second part of the cable fixed to the first movable means by a second fixing means, at least one of the fixing means comprising an end-piece operating in conjunction with the corresponding part of the cable, a housing designed to receive the end-piece, and locking means with dead point passage designed to oppose insertion of the end-piece in the housing when the force exerted on the locking means in an insertion direction remains lower than an insertion threshold and to enable insertion of the end-piece in the housing when the force exerted on the locking means in an insertion direction is greater than the insertion threshold. The fitter simply has to exert a sufficient force on the end-piece to insert the latter in its housing. The tightening operation is eliminated so that assembly can be performed with one hand and does not require a large access volume. Furthermore, passing the dead point gives the fitter a tactile feeling of engagement of the fixing, before any visual checking. The interlocking device may be of any kind: access door to the switchgear apparatus, other electrical switchgear apparatus or mechanical remote control for example. The electrical switchgear apparatus can be fixed or withdrawable.
Preferably, said locking means are able to oppose extraction of the end-piece from the housing when the force exerted on the locking means in an extraction direction remains lower than an extraction threshold and to enable extraction of the end-piece from the housing when the force exerted on the locking means in an extraction direction is greater than the extraction threshold. Disassembly is thus possible under the same conditions of ease and quickness.
According to one embodiment, the housing is formed by two notches made in two parallel flanges of a support.
The locking means preferably comprise a locking part able to take an unlocking position enabling the end-piece to be inserted in the housing and a locking position preventing the end-piece from being extracted from the housing, and a flexible return means urging the locking part to its locking position, the end-piece operating in conjunction with the flexible return means in such a way that the locking part is flexibly removed to its unlocking position when the end-piece is forcibly inserted in the housing. Locking with dead point passage is thus achieved in a particularly simple manner. It is then also easy to arrange for the flexible return means to operate in conjunction with the end-piece in such a way that the locking part is flexibly removed to its unlocking position when the end-piece is forcibly extracted from the housing.
Advantageously, the flexible return means is a spring acting directly on the end-piece. According to a preferred embodiment, the spring is provided with a first ramp and a second ramp shaped in such a way that the first ramp is able to operate in conjunction with the end-piece to clear the flexible return means when the end-piece is inserted, the second ramp being designed to operate in conjunction with the end-piece to hold the latter in position in its housing. The second ramp is such that it is able to operate in conjunction with the end-piece to clear the flexible return means when extraction is performed. The first and second ramp are shaped in such a way that the extraction force threshold is lower than the insertion force threshold.
The fixing means as described above can be used for fixing the core of the cable to the movable means of the electrical apparatus. It can also be intended for fixing the sheath with respect to the frame of the apparatus. The first and second means preferably each comprise an end-piece operating in conjunction with the corresponding part of the cable, a housing designed to receive the end-piece, and locking means with dead point passage designed to oppose insertion of the end-piece in the housing when the force exerted on the locking means in an insertion direction remains lower than an insertion threshold and to enable insertion of the end-piece in the housing when the force exerted on the locking means in an insertion direction is greater than the insertion threshold.
REFERENCES:
patent: 4400599 (1983-08-01), Rickmann
patent: 4405844 (1983-09-01), Dixon et al.
patent: 4546666 (1985-10-01), Secord
patent: 4626638 (1986-12-01), Samples et al.
patent: 4806710 (1989-02-01), Kalvaitis et al.
patent: 5164883 (1992-11-01), Little et al.
patent: 5227952 (1993-07-01), Romano et al.
patent: 54
Court Frédéric
Gerbert-Gaillard Alain
Parkhurst & Wendel L.L.P.
Scott J. R.
Square D Company
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