Abstract:
A fused switch unit is provided with two connecting contacts into which a fuse holder ( 20 ) can be inserted in order to hold a fuse link ( 30 ) with a head contact ( 31 ) and a foot contact ( 32 ). A first connecting contact ( 60 ) of the fused switch unit ( 10 ) can be connected via a controllable interruption contact ( 80 ) and by means of a bridging element ( 81 ) to a first of the contacts ( 31 ) of the fuse link ( 30 ). The fuse holder ( 20 ) or the fused switch unit ( 10 ) has a fuse state indicating device ( 40 ) with two contacts ( 42, 43 ) for an electrical connection for the connecting contacts ( 60, 70 ) of the fused switch unit ( 15 ). A first contact ( 42 ) of the fuse state indicating device ( 40 ) can be connected via an electrically conductive connection ( 91, 92, 82 ) directly and exclusively to the bridging element ( 81 ), and a second contact ( 42 ) of the fuse state indicating device ( 40 ) can be connected directly via an electrically conductive connection ( 50, 51, 52, 53, 71 ) to the second connecting contact ( 70 ) of the fused switch unit ( 10 ). This allows a high degree of flexibility for arrangement of the elements. Furthermore, it ensures a high level of operational reliability and safety, and little wear.

Description:
This application is an application filed under 35 U.S.C. Sec. 371 as a national stage of international application PCT/EP00/11041, which was filed on Nov. 8, 2000. 
    
    
     TECHNICAL FIELD 
     The invention relates to a fused switch unit having two connecting contacts into which a fuse holder can be inserted in order to hold a fuse link with a head contact and a foot contact, in which case a first connecting contact can be connected via a controllable interruption contact, which has a bridging element, to the foot contact or to the head contact of the fuse link. The fuse holder or the fused switch unit in this case has a fuse state indicating device for checking the fuse link which can be inserted into the fuse holder, or for checking the switching state. 
     BACKGROUND OF THE INVENTION 
     Fused switch units with a fuse holder for a fuse link are known in many different embodiments both for electrical protection in buildings and dwellings and for electrical protection of machines and production plant. 
     In order to monitor the state of the fuse link, or the switching state, it is advantageous to provide a fuse state indicating device for fused switch units such as these. Such state indicating devices produce a generally visual signal at least whenever the contact via the fuse link can no longer be produced when the fused switch unit is in a ready to operate state, since, for example, the conductive bridge in a fusible link has blown. The state indicating device should never emit a signal when the fused switch unit is in a ready to operate state and there are no defects in the fuse link. 
     Depending on the contact, it is possible to provide for the fuse state indicating device also to produce a signal when the fuse holder together with the fuse link is in a ready to operate position, but the fused switch unit is in a disconnected position, in which, for example, the contact is interrupted by a switch at a point within the fused switch unit. 
     Fused switch units and fuse holders are known with different types of contact for such a fuse state indicating device. For example, it is possible to fit a conductor for making contact with the state indicating device, together with the fusible conductor, in the fuse link itself. However, in particular, this has the disadvantage that it complicates the production and the matching of the fuse link, since the conductor for making contact with the fuse state indicating device occupies space which is normally intended for the quartz sand used for insulation of the fusible conductor. Furthermore, during operation, the fusible conductor produces heat, which can damage the conductor for making contact with the state indicating device. 
     A fuse holder with an integrated connecting line for a state indicating device is known from DE 198 00 779 A1. In this case, connecting lines which connect the fuse state indicating device directly to the head contact and the foot contact of the fuse link are provided in the fuse holder. In this refinement as well, there is a risk of the connecting lines, which are located in the vicinity of the foot contact in particular, being damaged if any switching arcs occur during switching processes. In addition, both the fuse state indicating device and all the connecting lines are located inside the fuse holder, so that this provides only a small amount of flexibility for the arrangement, in particular, of the visual indication of the fuse state indicating device. 
     SUMMARY OF THE INVENTION 
     One object of the present invention is to provide a fused switch unit with a fuse holder for holding a fuse link, which has a fuse state indicating device, and with a high degree of flexibility being provided for the arrangement of the elements of the fuse state indicating device and of the corresponding connecting lines, while at the same time ensuring a high level of operational reliability and safety, and little wear. 
     The object is achieved by a fused switch unit according to the invention. Claims  11  to  13  relate to a fused switch system which has at least two fused switch units according to the invention, as claimed in one of claims  1  to  10 . 
     According to the invention, the object is achieved in that a first contact of the fuse state indicating device is connected via an electrically conductive connection and exclusively to the bridging element of the interruption contact of the fused switch unit, and a second contact of the fuse state indicating device is connected directly via an electrically conductive connection to the second connecting contact of the fused switch unit. 
     In this case, the first contact is preferably connected via a conductor to a physically fixed end of a spring apparatus, which preloads the bridging element, of the interruption contact, with the spring apparatus also being composed of conductive material. 
     This firstly allows a high degree of variability to be achieved in the arrangement of the fuse state indicating device and of the corresponding connecting lines, since all the elements can be provided both in the fuse holder and in the fused switch unit. In particular, the preferred visual indication of the fuse state indicating device can be positioned, depending on the configuration of the fused switch unit, such that it is easily visible from the outside, without increasing the structural complexity. 
     The connecting lines for the fuse state indicating device may be located at a distance from those areas in which heat is produced during operation or in which switching arcs can occur during switching processes. 
     It is furthermore also advantageous to provide the majority of the connecting lines in the fused switch unit, since this, as the major component, will generally be designed to have a longer life than the fuse holders or fuse links, which in some circumstances need to be replaced more frequently. 
     Flexible connecting lines to the fuse state indicating device for making contact between the bridging element at a fixed end of a spring apparatus which preloads the bridging element are, furthermore, avoided, thus considerably reducing the risk of fuse state indicating device malfunctions caused, in particular, by wear. 
     The fuse state indicating device preferably has a visual indication, which is advantageously provided within a housing of a fuse holder. The housing of the fuse holder may in this case be a half-housing, which essentially holds only the area of the head contact of a fuse, or may be a full housing, which holds the fuse link essentially completely and leaves free any access points for making contact with the fuse link. The housing of the fuse holder and, possibly, parts of the fused switch unit in this case have a window, so that the visual indication can be seen from the outside. 
     It is particularly advantageous to provide an optical waveguide, so that light from the visual indication can be passed on at easily visible points. Firstly, this makes it possible for the light which is produced by the visual indication to be passed on independently of the position of the visual indication to easily accessible and easily visible points on the fused switch unit or the fuse holder while, secondly, it is also possible, in addition to or instead of the externally visible visual indication, to pass on the light that it is produced by the visual indication to a light-sensitive sensor, for example a photo cell, in order to allow automatic monitoring and, possibly, control of the fused switch unit. 
     This is particularly advantageous when a system is formed from a number of fused switch units, so that this allows reliable monitoring, without any delay, of all the fused switch units and, possibly, automatic control of the entire system. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     The invention will be explained in more detail in the following text with reference to the schematic drawings of two embodiments, in which: 
     FIG. 1 shows a cross-sectional view of a first embodiment of the fused switch unit according to the invention, with a fuse holder which has been removed from the fused switch unit and has a fuse link; 
     FIG. 2 shows the fused switch unit illustrated in FIG. 1, after the fuse holder together with the fuse link has been inserted; 
     FIG. 3 shows the fused switch unit, as illustrated in FIGS. 1 and 2, in its operating state; 
     FIG. 4 shows a second embodiment of the fused switch unit according to the invention in its operating state; and 
     FIG. 5 shows a photo cell monitoring strip for monitoring three fused switch units according to the invention. 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     FIG. 1 shows a first embodiment of a fused switch unit  10  according to the invention with two connecting contacts  60 ,  70  and with a fuse holder  20  together with a fuse link  30  having been removed from the fused switch unit  10 . The connecting contacts  60 ,  70  of the fused switch unit  10  may be used differently, depending on the application, but it is preferable for the connecting contact  60  to be used as an input contact, while the connecting contact  70  is used as the output contact. 
     The connecting contact  60  is connected via an interrupted contact line  83  to a contact region  84  for a foot contact  32  of the fuse link  30 . 
     A moving bridging element  81 , which is preloaded by a spring  82 , is used to bridge the interrupted contact line  83 . The bridging element  81  is operated by a switch system  120 . When the fused switch unit  10  is in the disconnected position shown in FIG. 1, a switching lever  121  is in an open position. The switching lever  121  is firmly connected to a cam disk  123 , which can rotate. A switching bolt  125  is in turn mounted on this cam disk  123  and, when the bridging element  81  is in the disconnected position, presses downward against the spring force of the spring  82  in FIG. 1, so that the bridging element  81  is sufficiently far away from the contact line  83 , and the contact line  83  is interrupted. There is thus no electrical connection between the connecting contact  60 , which is used in this case as an input contact, and the contact region  84  for the foot contact  32  of the fuse link  30 . 
     The connecting contact  70 , which is used as an output contact, is connected to a contact line  71  for making contact with a contact element  53  of the fuse holder  20  for a head contact  31  of the fuse link  30 . 
     The bridging element  81  is connected via the spring  82 , which is composed of a conductive material, to a connecting line  92  for a fuse state indicating device  40 . During insertion of the fuse holder  20  together with the fuse link  30  into the fused switch unit  10 , the connecting line  92  makes contact with a connecting line  91  for the fuse state indicating device. The connecting line  91  for the fuse holder  20  is connected, at a first contact point  42 , to a board  44  for controlling a light-emitting diode  41  in the fuse state indicating device  40 . 
     A second contact point  43  connects the board  44  via a contact apparatus  50  (which comprises a connecting line  51 , a spring  52  composed of conductive material and a contact element  53 ) and via the contact line  71  to the connecting contact  70 , which is used as an output contact. The spring  52  is used, during insertion of the fuse holder  20 , to reliably preload the fuse link  30  with pressure against the contact region  84  of the fused switch unit  10 , thus ensuring a reliable contact. 
     A housing  21 , which is in the form of a half-housing, for the fuse holder  20  has an opening above the light-emitting diode  41 . A part of a waveguide  100  is fitted in this opening, so that light from the light-emitting diode  41  is visible from the outside through the waveguide  100 , which is fitted in the region of the opening in the housing  21 , and through an opening  122  in the switching lever  121  of the fused switch unit  10 . 
     The waveguide  100  which is fitted in the opening extends via a waveguide conductor  101  to a second side opening in the housing  21  of the fuse holder  20 , where it has a second indicator region  102 , through which a proportion of the light emitted by the light-emitting diode  41  is likewise emitted. The light which is emitted from the indicator region  102  of the waveguide  100  can be detected, when a fuse holder  20  is inserted, by a photo cell  110  in the fused switch unit  10 , in order, for example, to trigger an additional indication, possibly an audible indication, or else in order to control the fused switch unit  10  or a system comprising a number of fused switch units  10  via a control system. 
     In the case of an overall system comprising a number of fused switch units  10 , the photo cell  110  can also be inserted into a monitoring strip  200 , which is shown in FIG. 5, having a number of photo cells  110  for monitoring the individual fused switch units  10  included in the overall system. It is thus possible to carry out a logic operation on all the photo cells  110  that are included in the monitoring strip  200  to ensure an automatic indication, or else automatic control, of the entire system or of individual fused switch units  10 . 
     FIG. 2 shows the embodiment of the fused switch unit  10  which is illustrated in FIG. 1, and into which the embodiment of the fuse holder  20  (which is likewise illustrated in FIG. 1) together with the fuse link  30  has been inserted in the region of the fused switch unit  10  provided for this purpose. During insertion of the fuse holder  20 , a part of the housing  21  makes contact with an ejection element  130  of the fused switch unit  10  which, as the fuse holder  20  is inserted further, is displaced downward against an ejection spring  132  in FIG.  2 . 
     During insertion, a part of the housing  21  of the fuse holder  20  likewise interacts with an incline  141  of a locking element  140  of the fused switch unit. In this case, during insertion of the fuse holder  20 , the locking element  140  is pressed to the left in FIG. 2 against a locking spring  142 , until the fuse holder has been completely inserted. The spring effect of the locking spring  142  then results in a latching element  143  (FIG. 1) of the locking element  140 , or the connecting line  92 , part of which is in the form of a continuation of the incline  141  or of the latching element  143 , of the fuse state indicating device  40  engaging in a latching groove  22  in the housing  21 , so that the fuse holder  20 , together with the fuse link  30 , is held fixed in its inserted and locked position in the fused switch unit. 
     The fuse holder  20  can be unlocked by manually compressing the locking element  140  against the spring force of the locking spring  142 . After it has been unlocked, the fuse holder  20  is automatically ejected out of the fused switch unit  10  by the spring force of the ejection spring  132 , via the ejection element  130 . 
     The switching lever  121  of the fused switch unit  10  is still in its disconnected position, so that the bridging element  81  is pressed downward by the switching bolt  125  against the spring force of the spring  82 , and the contact line  83  is interrupted between the contact region  84  for the foot contact and the connecting contact  60 , which is used as an input contact. The board  44  is now connected to the bridging element  81  via the contact point  46 , the connecting line  91 , the connecting line  92  and the spring  82 , although there is not yet any contact with the connecting contact  60 , since the switch  121  is in the disconnected positions that have just been described. 
     On the other side, the board  44  is connected directly to the connecting contact  70 , which is used as an output contact, via the second contact point  43 , the connecting line  51 , the spring  50 , the contact element  53  and the contact line  71 . 
     FIG. 3 shows the fused switch unit  10 , with the switching lever  121  located in its connected position. Moving the switching lever  121  to its connected position, results in the cam disk  123 , which is firmly connected to the switching lever  121 , being rotated through 90° clockwise. The switching bolt  125 , which is likewise connected to the cam disk  123 , follows the movement of the cam disk  123 , so that the bridging element  81  is pressed upward by the spring force of the spring  82  in FIG. 3, and bridges the contact line  83 . The connecting contact  60  is thus connected to the foot contact  32  of the fuse link  30  via the contact line  83 , the bridging element  81  and the contact region  84 . The head contact  31  of the fuse link  30  is connected to the connecting contact  70  via the contact element  53  and the contact line  71 , so that, with a serviceable fuse link  30 , the fused switch unit is isolated, and a contact is made between the connecting contacts  60  and  70 . 
     The board  44  of the fuse state indicating device  40  is now likewise connected to the connecting contact  60  via the first contact point  42 , the connecting line  91 , the connecting line  92 , the spring  82 , the bridging element  81  and the contact line  83 . 
     If the fuse link  20  is serviceable, that is to say it has a low impedance, there is a short-circuit link between the connecting contacts  60  and  70 , so that the two contact points  42  and  43  on the board  44  are at the same potential, as a result of which the light-emitting diode is not illuminated, via the controller for the board  44 . If the fusible conductor (which is not shown) in the fuse link  30  now blows, then the short-circuit contact between the connecting contacts  60  and  70  is interrupted. The first contact point  42  is thus at the same potential as the connecting contact  60 , while the contact point  43  is at the same potential as the connecting contact  70 , so that the light-emitting diode  41  in the fuse state indicating device  40  is illuminated due to the potential difference between the two contact points  42  and  43 . 
     The illumination of the light-emitting diode can be observed from the outside through the opening (which has already been described above) in the housing  21  of the fuse holder  20  and through the corresponding part of the waveguide  100  and through the opening  122  in the switching lever  121  of the fused switch unit  10 . Furthermore, the illumination of the light-emitting diode is also passed on via the waveguide conductor  101  to the second indicator region  102 , so that the photo cell  110  can detect the illumination of the light-emitting diode  41 . 
     In contrast to the embodiments of the fused switch unit  10  according to the invention as shown in FIGS. 1 to  3 , which are designed for a fuse link  30  in accordance with the DIN Standard, FIG. 4 shows a second embodiment of a fused switch unit  10  according to the invention, which is designed for a fuse link  35  as is used in accordance with NFC in France. However, with regard to its functional features, this second embodiment corresponds exactly to the embodiment shown in FIGS. 1 to  3 , so that it will not be described in detail once again. Identical or comparable components have been annotated with the same reference symbols. 
     FIG. 5 shows a monitoring strip  200  for three fused switch units  10 . The monitoring strip  200  has three photo cells  110 , which can be connected via connecting lines  201  and connecting contacts  202  to an external control apparatus in order, if necessary, to produce a further signal, for example an audible signal, or in order to control the fused switch unit, or the entire system, via a control apparatus. Known control apparatuses, logic circuits and computers can be used for this purpose. 
     The features which have been disclosed in the above description, the figures and the claims may be significant to the implementation of the invention both individually and in any desired combination. 
     
       
         
               
             
               
               
             
           
               
                   
               
               
                 List of reference symbols 
               
               
                 B 20-35 DE 
               
               
                   
               
             
             
               
                   
               
             
          
           
               
                 10 
                 Fused switch unit 
               
               
                 20 
                 Fuse holder 
               
               
                 21 
                 Housing (fuse holder) 
               
               
                 22 
                 Latching groove 
               
               
                 30 
                 Fuse link 
               
               
                 31 
                 Head contact 
               
               
                 32 
                 Foot contact 
               
               
                 35 
                 Fuse link 
               
               
                 40 
                 Fuse state indicating device 
               
               
                 41 
                 Light-emitting diode 
               
               
                 42 
                 First contact (fuse state indicating device) 
               
               
                 43 
                 Second contact (fuse state indicating 
               
               
                   
                 device) 
               
               
                 44 
                 Board 
               
               
                 50 
                 Contact apparatus 
               
               
                 51 
                 Connecting line 
               
               
                 52 
                 Spring 
               
               
                 53 
                 Contact element 
               
               
                 60 
                 Connecting contact 
               
               
                 70 
                 Connecting contact 
               
               
                 71 
                 Contact line 
               
               
                 80 
                 Interruption contact 
               
               
                 81 
                 Bridging element 
               
               
                 82 
                 Spring apparatus 
               
               
                 83 
                 Contact line 
               
               
                 84 
                 Contact region (foot contact) 
               
               
                 91 
                 Connecting line 
               
               
                 92 
                 Connecting line 
               
               
                 100 
                 Optical waveguide 
               
               
                 101 
                 Optical waveguide conductor 
               
               
                 102 
                 Indicator region 
               
               
                 110 
                 Photo cell 
               
               
                 120 
                 Switch system 
               
               
                 121 
                 Switching lever 
               
               
                 122 
                 Opening 
               
               
                 123 
                 Cam disk 
               
               
                 124 
                 Projection 
               
               
                 125 
                 Switching bolt 
               
               
                 130 
                 Ejection element 
               
               
                 132 
                 Ejection spring 
               
               
                 140 
                 Locking element 
               
               
                 141 
                 Incline 
               
               
                 142 
                 Locking spring 
               
               
                 143 
                 Latching element 
               
               
                 200 
                 Monitoring strip 
               
               
                 201 
                 Connecting line 
               
               
                 202 
                 Connecting contacts