Patent Application
20210287867
Priority is claimed to European Patent Application No. EP 20162206.5, filed on Mar. 10, 2020, the entire disclosure of which is hereby incorporated by reference herein.
The invention is related to a protection device for an electrical apparatus to realize a degree of protection, especially according to IP4x or IP40, comprising a front part, which has a cutout, through which a partially insulated cable or bar is insertable and a rear part, from which the non-insulated part of the cable or bar is extendable into the interior of the electrical apparatus.
Such a protection device, which usually is an electrical insulation of a cable or of a bar at a terminal or a housing of an electrical apparatus, is mostly made of rubber. The rubber often has a round or rectangular cutout. The flexible rubber pushes towards the cable or bar to create an IP protection which is a degree of protection.
A degree of protection reflects the suitability of an electrical apparatus to be used in a certain environment without creating a danger for persons, who use this apparatus. Degrees of protection are known under the classifications IP00 to IP69K. The degree of protection reflects the protection of active electrical parts, which lead current or voltage, against touch, against water or against the intrusion of debris, which are foreign bodies.
Some known protection devices have the drawback that they can be used only when the shape of an insulation jacket of a cable or bar is known. When the shape of the insulation jacket may have lots of shape variants, then a known protection device may not work properly anymore.
Especially, when there is a rectangular cutout and the shape or circumference of the insulation jacket is concave or convex, gaps between the protection device and the insulation jacket may occur.
In an embodiment, the present invention provides a protection device for an electrical apparatus to realize a degree of protection, comprising: a front part, which has a cutout, through which a partially insulated cable or bar is insertable; and a rear part, from which the non-insulated part of the cable or bar is extendable into an interior of the electrical apparatus, wherein a channel passes through the front part and the rear part, and wherein a stop is arranged within the channel, on which the insulation jacket of the insulated part of a cable or bar is configured to abut.
The present invention will be described in even greater detail below based on the exemplary figures. The invention is not limited to the exemplary embodiments. Other features and advantages of various embodiments of the present invention will become apparent by reading the following detailed description with reference to the attached drawings which illustrate the following:
In an embodiment, the present invention provides a protection device which reduces or prevents the migrating of foreign bodies through a gap between the protection device and an insulation jacket of a cable or bar.
In an embodiment, the present invention provides a protection device having a channel that passes through the front part and the rear part, wherein within the channel a stop is arranged, on which the insulation jacket of the insulated part of a cable or bar may abut.
According to the invention first it has been found that a protection device must provide a protection against foreign bodies. Further it has been found, that not a straight cutout has to be used to reach an IP class of protection, but to create a kind of labyrinth to prevent foreign particles, animals, test probes or similar bodies from entering the housing of an electrical apparatus and from touching life parts or from creating an arc. According to the invention the labyrinth comprises at least two areas. An inner area is used to create good insulation of the cable or bar, especially of a flex bar or of copper, and an outer area to create a labyrinth together with the insulation jacket of the cable or bar.
Advantageously, the channel has a first cross section in the front part and has a second cross section in the rear part, wherein the area of the first cross section is bigger compared to the area or the second cross section. A shape of an insulation jacket of a cable or bar, especially of a flex bar, may vary from bar to bar. By creating two areas having different sizes, a labyrinth has been embodied within the protection device. By using this labyrinth, a multiple insulation exists. A protection outside the protection device is given by the insulation jacket of the bar, especially a flex bar. Depending on the shape of the insulation jacket of a bar, it can occur that a body could penetratre inside the housing through a gap between the insulation jacket and the front part, in that case there is a further protection provided by the stop on which the insulation jacket abuts. The blank core of the cable or bar then is surrounded by the rear part having a cross section with a smaller area than the front part. Through this surrounding further gaps are prevented.
Further advantageously, the front part and the rear part internally are divided by a step or shoulder within the channel, which is the stop. A step or shoulder forms a defined edge, ridge or bead running around the bar, wherein the insulation jacket can abut without any gap on this edge, ridge or bead.
Advantageously, the length from an opening or the opening of the front part to the stop is in the range of 5 mm to 20 mm, preferably the length is 15 mm. Such a length is sufficient to reach a defined IP class. The general opening may be embodied in a wall of a cover which is arranged before the front part. The thickness of the wall increases the length in a preferred manner.
Further advantageously, the front part is connected with a plate which extends orthogonally or inclined relative to the direction of the extension of the channel. Such a plate allows assembling of the protection device easily in a housing or in a part of a housing of an electrical apparatus.
Advantageously, the front part and the rear part, and the plate as well, are made of a polymer, preferably are made of rubber. A polymer or rubber creates a very good electrical insulation and is a flexible material. Further such a protection device is compact, cheap and solid and accepts some tolerances and shapes of the insulation jacket or of the bar. It could be used rubber as well as plastic or another insulating material to generate or produce the protection device.
Further advantageously, the cross section of the cutout is rectangular and the cross sections of the channel are rectangular as well. Through this a flex bar having a core of copper which has a rectangular cross section as well may be inserted easily into the protection device.
An electrical apparatus, comprising a partially insulated cable or a bar advantageously comprises a protection device described in this specification, wherein the insulation jacket of the cable or bar abuts on the stop and wherein the cable or bar without an insulation jacket passes through the channel within the rear part and from there extends to a terminal or contact area. Such an apparatus is protected against migrating of foreign particles into its interior.
Advantageously, the protection device and/or the front part is connected to a plate which is inserted with its side margins into nuts of rails in a part of the housing of the apparatus. Through this, the protection device can be arranged in the housing without any screws.
Further advantageously, the part is a removable cover, in which the nuts are designed and which cover is a removable part of the housing. Through this, the protection device is easily to assemble. The cover can be removed and the protection device may be connected with the cover. Then the whole assembly of cover and protection device may be fitted together with the rest of the housing.
Advantageously, a first outer insulation area is provided by the part of the cable or bar, which is surrounded by the insulation jacket, wherein a middle or second insulation area is provided by the front part and the part of the cable or bar, which is surrounded by the insulation jacket and is surrounded by the front part as well and wherein a third or inner insulation area is provided by the blank part of the cable or bar, which is not surrounded by the insulation jacket but which is surrounded by the rear part.
The protection device may be used in breakers or switchgears, preferably in low voltage switchgears.
The bar 2 is a flexbar, having a cuboid-shaped core of copper. Shape 1a is the ideal shape having a rectangular cross section.
Shape 1b has convex curvatures and shape 1c has concave curvatures. Those aberrations from the ideal shape lead to gaps between a rectangular cutout of a protection device and the insulation jacket.
A foreign body of a size of 1 mm should not penetrate such a gap.
A channel 7 passes through the front part 3a and the rear part 3b, wherein within the channel 7 a stop 8 is arranged, on which the insulation jacket 1 of the insulated part of the bar 2 abuts.
This stop 8 together with the front part 3a and the rear part 3b create a labyrinth designed by the front part 3a and the rear part 3b housing this stop 8. This labyrinth prevents a foreign body from penetrating into the interior of the electrical apparatus. The shape of the labyrinth is embodied in such a way that a degree of protection does not depend on the shape of an insulation jacket 1 of any bar 2 connected to the housing 14 of an electrical apparatus 4.
The cross section of the cutout 5 is rectangular and the cross sections of the channel 7 are rectangular as well.
The part is a removable cover 15, in which the nuts 13 are designed and which cover 15 is a removable part of a housing 14.
All embodiments show, that a first or outer insulation area is provided by the part of the cable or bar 2, which is surrounded by the insulation jacket 1, wherein a second or middle insulation area is provided by the front part 3a and the part of the cable or bar 2, which is surrounded by the insulation jacket 1 and is surrounded by the front part 3a as well and wherein a third or inner insulation area is provided by the blank part or core of the cable or bar 2, which is not surrounded by the insulation jacket 1 but which is surrounded by the rear part 3b. The blank part of the bar 2 is the copper core of the bar 2. The bar 2 is a flexbar, which is so thin, that it may be bended or deformed in an easy manner or by its own weight, when being clamped at one end and the other end being free.
While the invention has been illustrated and described in detail in the drawings and foregoing description, such illustration and description are to be considered illustrative or exemplary and not restrictive. It will be understood that changes and modifications may be made by those of ordinary skill within the scope of the following claims. In particular, the present invention covers further embodiments with any combination of features from different embodiments described above and below. Additionally, statements made herein characterizing the invention refer to an embodiment of the invention and not necessarily all embodiments.
The terms used in the claims should be construed to have the broadest reasonable interpretation consistent with the foregoing description. For example, the use of the article “a” or “the” in introducing an element should not be interpreted as being exclusive of a plurality of elements. Likewise, the recitation of “or” should be interpreted as being inclusive, such that the recitation of “A or B” is not exclusive of “A and B,” unless it is clear from the context or the foregoing description that only one of A and B is intended. Further, the recitation of “at least one of A, B and C” should be interpreted as one or more of a group of elements consisting of A, B and C, and should not be interpreted as requiring at least one of each of the listed elements A, B and C, regardless of whether A, B and C are related as categories or otherwise. Moreover, the recitation of “A, B and/or C” or “at least one of A, B or C” should be interpreted as including any singular entity from the listed elements, e.g., A, any subset from the listed elements, e.g., A and B, or the entire list of elements A, B and C.
| Number | Date | Country | Kind |
|---|---|---|---|
| 20162206.5 | Mar 2020 | EP | regional |
