WO2005101443A2 - Switchgear - Google Patents

Abstract

The invention relates to a switchgear (S) for electrical installations, said switchgear comprising a housing (2) provided with terminal connections (1). In order to increase the level of security against flashovers between the electroconductive outer parts of two adjacent switchgears, at least one shielding element (3) formed as a single component on the housing is provided in the region of the terminal connection (1), or at least one recess (8), cavity (8) or the like is provided on at least one part of the housing and/or at least one part formed on the housing (2) in order to lengthen the tracking path. Furthermore, said switchgear (S) for electrical installations, comprising a housing (2) having at least one terminal connection (1), is provided with means for completely removing the clamping screw (15) from the clamping opening (17) in order to simplify the introduction of ring cable terminals.

Description

 switchgear

The invention relates to a switching device with housing, in particular circuit breaker, wherein at least one terminal is arranged in a housing formed in the switch housing, wherein the receptacle is closed at the front side at least partially by a cover.

Such switching devices are used as a circuit breaker, in particular circuit breaker, in a variety of applications in use.

Electrical switching devices must comply with specified safety regulations. The dense use of electrical switching devices such as in control boxes makes special security features for such switching devices necessary.

Regulations such as the US UL 489 specify minimum distances between the externally accessible current-carrying conductors of neighboring electrical switching devices. For example, for switchgear up to an operating voltage of UN less than or equal to 300N, an air gap of at least 19.1 mm between two adjacent live conductors is prescribed. At an operating voltage of U _Ν > 300N, the prescribed minimum air gap between two adjacent live conductors is already 25.4mm. Such air gaps between densely packed switching devices are realized on wider housing. This creates switching devices, which have housing volumes or housing widths that would not be necessary for their function. In addition to the resulting higher costs for the production, storage and transport of such switching devices, they require above all a lot of space.

In addition to the flashover between the electrically conductive parts of two adjacent switching devices, especially the leakage currents occurring at the housing parts of electrical components represent a safety risk. An electrical flashover can not only take place through the air. The housing walls of an electrical device provide far less resistance to the electrical current than an air gap. Correspondingly larger are the prescribed minimum distances along a housing wall to prevent a conductive connection of two adjacent terminals by leakage currents. When juxtaposing several switching devices, the leakage current path typically corresponds to the air flow path. Therefore, switching devices to meet the required minimum leakage current path are usually larger than the air flow path required would do. The use in the low voltage range of conventional, narrow designs for switching devices from a certain operating voltage is therefore not possible. It is an object of the present invention to provide a switching device of the type mentioned, which has a high security against flashover between the electrically conductive parts of two adjacent, in particular identical, switching devices, without significantly changing the width of the switching device. Another object of the invention is to provide a switching device that has an unchanged as possible outside dimensions increased security against leakage currents between the electrically conductive parts of two adjacent, especially identical, switching devices. Another object is to provide a switching device having a plurality of switching paths, in which an increased security against rollover or against leakage between two adjacent terminals is given. According to the invention this is achieved in that at least one, the front-side cover superior plate-shaped or rib-shaped shielding element is integrally formed integrally with the housing.

As a result, with the width of the switching device remaining the same, the air gap and the leakage current path to an adjacent switching device and to its terminals can be increased. Thus, switching devices with almost identical external dimensions as in low-voltage devices can be used at higher threshold voltages. This can effectively shield the terminals against flashovers. In continuation of the invention can be provided that extends the plate-shaped or rib-shaped shielding substantially over the entire housing height. As a result, the area between a terminal opening and a nearest Klemmschrauböffhung or another exposed conductor can be effectively protected against flashovers.

In this connection, in a further development of the invention in a switching device in which in the front cover terminal openings and / or Klemmschraubenöffhungen are formed for the terminals, be provided that two substantially parallel to each other of the clamping openings and the clamping screw openings Abschirmelemente are arranged so that between two adjacent terminal openings at least two separate shielding elements are provided, which form a free gap between the two shielding elements. As a result, in the case of adjacent terminal openings, the path of the leakage currents occurring is very effectively lengthened, since the creeping path is essential due to the gap is extended. By arranging two shielding elements, the switching device on two sides of the required air gap to the adjacent terminals. According to a further embodiment of the invention, it may be provided that the shielding elements are arranged offset parallel to a housing outside and at a distance from the housing outside to the inside, so that when two switching devices arranged next to each other two shielding elements next to each other form a free gap. As a result, the path of the leakage current occurring is juxtaposed with juxtaposed similar switching devices, since the shielding of two adjacent, similar switching devices are not superimposed and results in a significantly extended creepage distance by the distance between the shielding and the gap formed thereby.

In a further embodiment of the invention can be provided that in the region of f eien gap recesses on the housing, preferably on the outside of the housing, in particular in the region of Klemmschrauböffhung, are provided to increase the depth of the free gap. Due to the geometry of the housing, the clamping screw openings present a juxtaposition of similar switching devices arranged side by side, which represents a particular danger due to leakage currents which are effectively reduced in this way.

In a continuation of the invention, it can be provided that the at least one shielding element has an indentation, preferably extending over the entire surface of the shielding element, on at least one side, wherein the indentation forms a raised edge region for this. This further extends the leakage current path. In this connection, it can be provided in a continuation of the invention that the at least one shielding element comprises at least one stiffening rib. As a result, the shielding element can withstand higher mechanical stresses, such as occur during assembly, without being affected. Defective shielding elements represent an increased security risk.

The invention further relates to a switching device, in particular circuit breaker, for electrical systems with a terminals having housing, wherein at least one housing part at least one arrangement for extending the creepage path is provided. The object of the invention is to provide a switching device in which an increased security against leakage currents between the electrically conductive regions of the terminals, in particular the Klemmschrauböffnungen, two adjacent identical switching devices is given, with unchanged outer dimensions as possible. According to this Invention, this is achieved in that a respective recess, recess or the like. Side of one, the terminal associated Klemmschraubenöffhung on the outside of the housing is arranged, wherein between two juxtaposed housings in the area of Klemmschraubenöffhungen a free gap is formed. As a result, with an unchanged housing width, the leakage current path can be extended by a substantial amount, which keeps the dimensions of switching devices at the level of low-voltage switchgear even at higher operating voltages. Furthermore, the invention relates to a switching device, in particular a circuit breaker, for electrical systems with a housing, with at least one cable clamp, comprising a movable box, a fixed box wrapped around this and a through opening of the solid box into a thread of the movable box with a head screwable against a clamping support clamping screw, the movable box forms together with the fixed box by means of a clamping screw adjustable Klemmöffhung for cable ends, further comprising a formed between the head of the clamping screw and the fixed box Klemmöffhung for cable lugs. Switchgear with such cable clamps are known and widely used. However, with such cable clamps only cable ends and so-called. Fork cable lugs can be clamped. Suction. Ring cable lugs can not be clamped with such a clamp or only with great difficulty.

To clamp a ring cable lug, the clamping screw must completely release the clamping opening to allow insertion of the ring cable lug into the clamping opening.

In some embodiments of switches means are provided to prevent the falling out of the clamping screw from the cable clamp. Such switches are completely eliminated for operation with ring cable lugs.

In the embodiments that allow removal of the clamping screw from the cable clamp, a special tool or gravity is necessary for this purpose. Apart from the fact that installed electrical appliances can not be brought into a favoring the falling out of the clamping screws positions in many cases, falling conductive parts in an electrically sensitive environment also pose a high security risk. The use of special tools for extracting the clamping screw from the clamping area also provides an unsatisfactory solution. The handling of a Screw with pliers is tedious, and the screw can also be lost in this way.

The object of the invention is therefore to provide a switching device according to the preamble of

Specify claim 9, with which the known disadvantages can be avoided, and which allows the safe operation of ring cable lugs on such a switch.

According to the invention this is achieved in that means are provided for completely unscrewing the clamping screw from the Klemmöffhung.

This can ensure that the clamping screw the clamping area for the

Inserting a ring-lug releases, without additional aids or without

Help by gravity and without removing the clamping screw from the switching device.

In continuation of the invention can be provided that the means for complete

Unscrew the clamping screw from the Klemmöffhung, a next to the

Clamping screw head arranged thread-free area of the clamping screw comprises.

This makes it possible to provide next to the screw means that are not affected by the thread of the screw.

In this context, it can be provided in continuation of the invention that the thread-free region of the clamping screw has a cross-sectional taper. Thereby, a portion can be formed on the clamping screw, which is adapted to receive a part with an internal thread, without moving it.

In a further embodiment of the invention can be provided that the means for completely unscrewing the clamping screw from the Klemmöffhung a at the from

Box side facing away from the terminal support of the terminal and parallel to this anti-rotation plate arranged whose thickness at most equal to the height of the unthreaded portion of the clamping screw.

According to a further embodiment of the invention can be provided that the plate has a passage opening for the clamping screw, which at least parts of a

Thread includes. By the characterizing features of claims 12 and 13, such a plate can be arranged with an internal thread on the thread-free cross-sectional constriction of the clamping screw, without affecting these in the normal operation of the Klemmöffhung for cable ends. When unscrewing the clamping screw from the

Thread of the moving box, the threaded part of the plate takes over the screw and ensures the complete unscrewing from the clamping area, which is now formed between the plate and the clamping pad.

The invention will be described with reference to the accompanying drawings in which

Embodiments are shown, described in more detail. Showing:

Fig. 1 shows two switching devices according to claim 1 and 6 in axonometric representation;

FIG. 2 shows two switching devices according to FIG. 1 in plan view; FIG.

Fig. 3 is a cable clamp of a switching device according to claim 9 in axonometric

Presentation;

4 shows a cable clamp according to FIG. 3;

FIG. 5 shows a cable clamp according to FIG. 3 with a ring cable clamp; FIG.

6 is a sectional view of a switching device according to FIG. 1 with a cable clamp according to FIG

Fig. 5 in axonometric view.

Figs. 1 and 2 show two switching devices S according to the invention, with housing 2, in particular

Circuit breaker in which at least one connection terminal 1 is arranged in a receptacle 36 formed in the housing 2, the receptacle 36 being closed at the front by at least one area by a cover 30, at least one plate-shaped or rib-shaped one projecting beyond the front cover 30

Shielding element 3 is integrally formed on the housing 2.

The invention is not limited to the application in switching devices S with only one switching path, but may be used in switching devices S with a plurality, in particular two or four switching paths.

Inventive switching devices have a housing 2, which is constructed of insulating material. The housing has a base body with housing outer sides 32, which in the preferred arrangement of switching devices according to the invention on a mounting rail, as

Contact surface is provided to an adjacent switching device of the same or different type. The main body of the housing 2 erfϊndungsgemäßer switching devices S also has a top surface 37, which openings for controls, such as a handle 38 or a test button, may have. The main body points further

Housing front sides 35, which are connected to the housing outer sides 32 substantially, or limited by these.

The housing 2 has at least one receptacle 36 for at least one connection terminal 1. The receptacle 36 is arranged in the housing 2 in the region of the housing front side 36 and closed by a front cover 30 at least partially. It can be provided to perform the cover integral with the housing 2, such as when, as in the illustrated preferred embodiments, a two-part housing is provided. But it can also be provided to close the receptacles 36 by means of removable covers 30 or to cover. Preferably in the cover 30 or in the housing 2 Klemmöffhungen 6 and or Klemmschraubenöffhungen 7 are formed for the terminals 1.

In switch boxes and fuse boxes are a variety of switching devices S, in particular circuit breakers, arranged in a confined space. In order to accommodate the largest possible number of such switching devices S on a limited area, they are usually relatively narrow and designed so that they can be arranged side by side in an advantageous space-saving manner. In the densely packed juxtaposition increases the risk of sparkover due to insufficient safety distances between the exposed current-carrying conductors. In general, these conductors are parts of the terminals 1, which can not be completely isolated. It is therefore necessary to maintain safety distances between the live conductors.

In relevant regulations, such as the US UL 489 minimum distances between the externally accessible current-carrying conductors are given, which has to meet a switching device S in order to be brought into circulation in the market in question. For example, an air gap of at least 19.1 mm between two adjacent current-carrying conductors is prescribed for switching devices S up to an operating voltage of U _M less than or equal to 300V. At an operating voltage of U _N > 300 V, the prescribed minimum air gap between two adjacent live conductors is already 25.4 mm.

Usually used up to voltages of 300V switchgear S meet the required minimum air gap purely by the size of the housing 2, which is necessary to record the electromagnetic and / or electromechanical components of the switching device S. Switching devices S with such external dimensions could also be used at much higher operating voltages. This is counteracted by the required minimum air path between adjacent live conductors.

The minimum air path between neighboring live conductors required for use with operating voltages above 300 V leads to housing dimensions that are not justified by the function of the switching device S. Above all, the width of the switching device S increases, which the number of switching devices S to be accommodated on a given area is drastically reduced.

In order to circumvent or avoid this disadvantage and to be able to use switchgear S with smaller external dimensions, in particular with smaller widths or short distances to adjacent terminals, at high operating voltages, switchgear devices S according to the invention have at least one front cover 30 according to claim 1 superior plate-shaped or rib-shaped shielding element 3, which is integrally formed on the housing 2. As a result, the case width can be maintained at the level of low-voltage switchgear (e.g., about 17.5 mm). This makes it possible to arrange much more switching devices S on a given area, than was previously possible.

It has been found to be particularly advantageous that the at least one shielding element 3 is designed as a substantially flat plate 4 or rib 4. Such a plate 4 or rib 4 makes it possible in a particularly simple way to increase the air gap between the terminals 1 adjacent switching devices S. The concrete shape of such a plate 4 or rib 4, and generally the shape of a shielding element 3 according to the invention results from the housing dimensions and the required air gaps between two adjacent switching devices S.

In a particularly preferred embodiment of the invention may be provided, that the plate-shaped or rippenfb ^'-shaped shield member 3 substantially over the entire housing height extends h, whereby also the area between a Klemmenöffhung and a nearest Klemmschrauböffhung can be effectively protected against impact. The housing height h designates the height of the housing 2 in the region of the housing front side 35, or in the region of the housing side, on which the terminals are arranged.

Shielding elements 3, especially plates 4 or ribs 4, especially as often listed from thin-walled plastic material, have a significant risk of destruction. Improper handling, especially during assembly of the connections or the switching device itself can lead to damage or to a breaking off of a shielding element 3. Damaged or non-existent electrical shielding 3 represent a security risk and can lead to the failure of equipment or equipment or injury to people. Therefore, it has proved to be advantageous that the at least one shielding element 3 comprises at least one stiffening rib 5. Such Stiffening rib 5 increases the mechanical strength of the shielding element 3 with minimal effort. It is envisaged to adapt the type and specific design of the stiffening rib 5 to the specific circumstances.

The invention is particularly aimed at the use of switching devices S, which are provided to a side-by-side arrangement, and are characterized by uniform housing dimensions. In such switching devices S, in which it is not clear before mounting on which outside the next switching device S is arranged, it is advantageous if the switching device S has two spaced-apart shielding 3. The air gap between the current-carrying parts of two adjacent switching devices S can be extended most effectively when the shielding 3 are arranged substantially parallel to the clamping openings 6 and / or the Kleschraubenöffhung 7 of the terminals 1. In this way, the air gap can be most effectively extended with a minimum use of shielding 3, regardless of where in a possible switching device network, the switching device S is arranged.

A possible conductive connection between adjacent live parts by air is not the only security risk in the operation of electrical switching devices S in a small space. Virtually every solid, including insulators, have a much lower resistance than air. Parasitic electrical currents, so-called leakage currents, can propagate along housing surfaces and thus lead to a conductive connection to an adjacent switching device S.

In order to prevent this, there are regionally binding regulations for the minimally existing creepage paths between the exposed current-carrying conductors of two adjacent switching devices S. Due to the lower resistance than the air that the housing 2 opposes to the electrical current, the required minimum creepage distances are required longer than the air distances. For example, the US-American UL 489 for switching devices S up to an operating voltage of U _N equal to or less than 300 V provides a creepage distance of at least 31.8 mm between two adjacent live conductors. At an operating voltage of UN> 300V, the prescribed creepage distance between two adjacent live conductors is already WeStkππi. conventional switching devices S arranged side by side without additional design measures, the creepage path is equal to the air gap. This implies that electrical switching devices S, which meet the required creepage distances, many times are greater than would be necessary for the safe fulfillment of the switching tasks. This results in a significantly increased space requirements and associated costs. Switching devices S according to the invention preferably have two essentially parallel shielding elements 3 on both sides of the clamping openings 6 and / or the clamping screw openings, so that at least two separate shielding elements 3 are provided between two adjacent terminal openings 6, forming a free gap 31 between the two shielding elements 3 , In switching devices S, which have more than one switching path, it can therefore be provided that two shielding elements are arranged between the adjacent connection terminals of a switching device S. For switching paths which are arranged next to a housing outer side 32, it is preferably provided that the shielding elements 3 are arranged offset parallel to a housing outer side 32 and at a distance from the housing outer side 32 inwards, so that when two switching devices S arranged next to each other two shielding elements 3 closest to one another forming free gap 31. This can be clearly seen in FIGS. 1 and 2. The shielding 3, executed in FIG. 2 as a plate 4 or rib 4, are moved away from the housing outside 32 away so far that it is ensured that the shielding 3 no contact with any existing adjacent switching device S or to an have this existing shield 3. As a result, the shielding elements 3 of adjacent switching devices S are not adjacent to one another and thus contribute to the lengthening of the creepage path.

In the preferred embodiments of switching devices S according to the invention, the shielding elements 3 do not extend to the area around the Klemmschrauböff openings 7. However, it may also be provided to arrange in this area shielding 3, or provide shielding 3, which also extend into this area , In embodiments in which the shielding elements 3 do not extend up to the region of the clamping screw openings 7, it is provided that in the region of the free gap 31 recesses 8 are provided on the housing 2, preferably on the outside of the housing 32, in particular in the area of the clamping screw opening 7 are to increase the depth t of the free gap 31, which is determined substantially by the shielding 3, in the region of Klemmschrauböffhung 7 to the depth ti without increasing the shielding 3. The clearly visible in Fig. 1 wells 8 lead to a significant extension of the existing creepage distance with respect to conventional components unchanged housing width. The design, number and shape of the According to the invention recess 8 is dependent on the local conditions and is adapted to the geometry of the respective switching devices S.

In order to further extend the leakage current path, without increasing the depth t of the gap 31 or the shielding elements 3, it can be provided that the at least one shielding element 3 on at least one side, preferably on the entire surface of the shielding 3 extending, indentation 33, wherein the indentation 33 forms a raised edge region 34 for this. By such a recess 33 or by the edge region 34 formed thereby the Kriechstromweg is further extended. It can also be provided to arrange a rough surface or a surface relief on at least one shielding element 3, as a result of which the leakage current path is further extended. 1 and 2 show two juxtaposed particularly preferred embodiments inventive switching device S, in particular circuit breaker, for electrical systems with a terminal 1 having housing 2, wherein at least one housing part at least one arrangement for extending the creepage path is provided, each having a recess 8 side of one, the terminal 1 associated Klemmschraubenöffhung 7 is disposed on a housing outer side 32, wherein between two juxtaposed housings 2 in the area of Klemmschraubenöffhungen 7, a free gap 31 is formed.

It is advantageous to arrange the at least one recess 8 in the region of a connection terminal 1, since in this area the occurrence of leakage currents is increasingly to be expected. Above all, it is advantageous to arrange a recess 8 each side of the Klemmschraubenöffhung 7 on the outside of the housing. In this way, with a minimum of material removed from the housing surface, the creepage distance can be extended most effectively since a free gap 31 is thereby formed. The depression can also be formed approximately by a recess.

3 to 6 show the terminal 1 of a switching device S, in particular a circuit breaker, for electrical installations with a housing 2, with at least one terminal 1, comprising a movable box 10, a fixed box 11 wrapped around this and a through a through opening. 9 the fixed box in a thread 12 of the movable box with a head 13 against a clamping pad 14 screwed clamping screw 15, the movable box 10 together with the fixed box 11 an adjustable by means of the clamping screw 15 terminal opening for cable ends 16, further comprising a between the Head 13 of the clamping screw 15 and the fixed box 11 formed Klemmöff ung for cable lugs 17, wherein means for complete

Unscrewing the clamping screw 15 are provided from the Klemmöffhung 17.

Switchgear S have in many cases terminals 1, to which for receiving

Cable ends and / or fork cable lugs are suitable.

Suction. Ring cable lugs R can not be clamped with such a terminal 1 or only with great difficulty. For inserting a ring cable lug R into a

Terminal 1 must be ensured that the clamping screw 15 the clamping area

17 releases in front of the clamping pad 14.

It is not uncommon to provide means that the clamping screw 15 am

Prevent falling out of the Klemmschrauböffhung 7. Switchgear S with such

Terminals 1 are unsuitable for operation with ring cable lugs R. If it is possible to remove the clamping screw 15, this must be done with the help of a

Special tools or gravity happen.

The means provided in a switching device S according to the invention ensure complete unscrewing of the clamping screw 15 from the clamping opening 17 and allow the operation of a switching device S according to the invention with ring cable lugs R.

The means for completely unscrewing the clamping screw 15 from the Klemmöffhung

17 comprise a clamping screw 15, which has a next to the screw head 13 arranged unthreaded region 18, which also has a compared to

Cross-section of the thread has a cross-sectional taper 19.

Furthermore, the means for completely unscrewing the clamping screw 15 from the

Klemmöffhung 17 a on the side facing away from the box 11 side of the clamping pad 14 of

Terminal 1 and parallel to this non-rotating plate 20, whose

Thickness at most equal to the height of the unthreaded portion 18 of the clamping screw 15.

It is envisaged that the plate 20 a Durchführungsöffhung 21 for the

Clamping screw 15 which comprises at least parts of a thread 22. This

Through opening 21 may be executed open edge. This makes it possible to realize a particularly simple partial thread 22.

The plate 20, which need not necessarily meet the shapes of the plate 20 shown in FIGS. 3 to 6, is between the clamping support 14 of the fixed

Box 11 and the clamping screw 15 is arranged and has the opportunity to

Support housing parts. It should be noted, however, that the plate 20 may be so far away from the clamping pad 14, before it rests against the housing parts that the case resulting gap between terminal support 14 and plate 20 is adapted to receive a ring terminal R cable. Embodiments for accommodating more than one ring cable lug R can also be provided.

In the case of the closed or partially closed connection terminal 1, for example when clamping a cable end, the plate 20 is arranged on the thread-free, cross-section-tapered region 18, 19 of the clamping screw 15. For this purpose, the clamping screw 15 must be screwed through the plate 20.

If now the terminal 1 are opened so far that the Klemmöffhung for cable lugs 17 is released by the clamping screw 15, the screw 15 is actuated such that this leads to the opening of the terminal 1. If the terminal 1 is fully open and the clamping screw 15 is moved in the same way, so you unscrewed the clamping screw 15 from the last threads of the thread 12 in the moving box 10 out. In this case, the clamping screw 15 lifts over the clamping pad 14 and takes the plate 20 with, until the movement of the plate 20 is inhibited by housing parts. A further rotation of the clamping screw 15 now causes the thread of the clamping screw 15 screwed into the partially existing thread 22 of the plate 20. Since the plate 20 is prevented from moving radially by housing parts, further rotation of the clamping screw 15 causes the clamping screw 15 to move out of the fixed box 11 and out of the terminal block 17, as shown in FIG. After release of the clamping opening 17, a ring cable lug R is inserted into the clamping opening 17. It may be provided that the clamping screw 15 projects so far out of the terminal screw opening 7 at complete opening of the Klemmöff 17, that this is manually removably bar. However, this is not necessary for the operation of a switching device S with ring cable lugs R. In the preferred embodiment of a switching device S according to the invention, means are provided which prevent the clamping screw 15 from falling out of the clamping screw opening 7. This can be achieved for example by a small diameter reduction in the Klemmschrauböffnung 7. As a result, the clamping screw 15, the Klemmschraubenöffhung 7 no longer leave, or be removed from this. The length of the clamping screw 15 must be selected such that this almost completely unscrewing out of the thread 12 of the movable box 10, the plate 20 presses against the housing 2 such that the partial thread 22 of the plate 20 comes into engagement with the thread of the clamping screw 15 , Of course, the length of the Thread 12 of the movable box 10 are selected such that this condition is met.

To close the terminal 1, only the clamping screw 15 must be moved in the intended direction of rotation. Just before the clamping screw 15 at

Partial thread 22 of the plate 20 is disengaged, the clamping screw 15 engages with the thread 12 of the movable box 10 and can now be closed in a known manner.

6 shows a switching device S with a shielding element 3 and a connection terminal 1 with a ring cable lug R arranged therein.

Claims

PATENT APPLICATIONS 1. switching device (S) with housing (2), in particular circuit breaker, wherein at least one terminal (1) in a housing (2) formed receptacle (36) is arranged, wherein the receptacle (36) front side at least partially by a cover (30) is closed, characterized in that at least one, the front cover (30) superior plate-shaped or rib-shaped shielding element (3) is integrally formed on the housing (2). 2. Switching device (S) according to claim 1, characterized in that the plate-shaped or rib-shaped shielding element (3) extends substantially over the entire housing height (h). 3. Switching device (S) according to claim 1 or 2, wherein in the front cover (30) Klemmöffhungen (6) and / or Klemmschraubenöffhungen (7) for the terminals (1) are formed, characterized in that on both sides of the Klemmöffhungen (6 ) and / or the Klemmschraubenöffhungen (7) two substantially mutually parallel shielding (3) are arranged so that between two adjacent terminal openings (6) depending at least two separate shielding elements (3) are provided which a free gap (31) between the two Form shielding (3). 4. Switching device (S) according to claim 3, characterized in that the shielding elements (3) parallel to a housing outer side (32) and at a distance from the housing outer side (32) are arranged offset inwards, so that when juxtaposed switching devices (S) two next shielding elements (3) form a free gap (31). 5. Switching device (S) according to claim 3 or 4, characterized in that in the region of the free gap (31) recesses (8) on the housing (2), preferably on the Housing outside (32), in particular in the region of Klemmschrauböffhung (7) are provided to increase the depth (t) of the free gap (31). 6. Switching device (S) according to one of claims 1 to 5, characterized in that the at least one shielding element (3) on at least one side, preferably over the entire surface of the shielding element (3) extending, indentation (33), wherein the indentation (33) forms a raised edge region (34). 7. Switching device (S) according to one of claims 1 to 6, characterized in that the at least one shielding element (3) at least one stiffening rib (5). 8. Switching device (S), in particular circuit breaker, for electrical installations with a terminal (1) having housing (2), wherein at least one housing part at least one arrangement for extending the creepage path is provided, characterized in that one recess (8) a free gap (31) is formed between two juxtaposed housings (2) in the region of the Klemmschraubenöffhungen (7) side of one, the terminal (1) associated Klemmschraubenöffhung (7) on a housing outer side (32). 9. Switching device (S), in particular circuit breaker, for electrical installations with a housing (2), with at least one connection terminal (1), comprising a movable box (10), a loop around this fixed box (11) and through a through hole ( 9) of the solid box (11) into a thread (12) of the movable box (10) with a head (13) against a clamping pad (14) screwed clamping screw (15), wherein the movable box (10) together with the fixed box (11) by means of a clamping screw (15) adjustable terminal opening for cable ends (16) further comprising one between the head (13) of the clamping screw (15) and the fixed box (11) formed Klemmöffhung for cable lugs (17), characterized in that means for completely unscrewing the clamping screw (15) from the Klemmöffhung (17) are provided. 10. Switching device (S) according to claim 9, characterized in that the means for completely unscrewing the clamping screw (15) from the Klemmöffhung (17), a next to the clamping screw head (13) arranged thread-free area (18) of the clamping screw (15). 11. Switching device (S) according to claim 10, characterized in that the unthreaded region (18) of the clamping screw (15) has a cross-sectional taper (19). 12. Switching device (S) according to one of claims 9 to 11, characterized in that the means for completely unscrewing the clamping screw (15) from the Klemmöffhung (17), one on the side facing away from the box (11) of the clamping support (14) the terminal (1) and parallel to this against rotation arranged platelets (20) whose thickness at most equal to the height of the unthreaded portion (18) of the clamping screw (15). 13. Switching device (S) according to claim 12, characterized in that the plate (20) has a Durchführungsöff tion (21) for the clamping screw (15), which comprises at least parts of a thread (22).