Classifications

• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01C—RESISTORS
  • H01C7/00—Non-adjustable resistors formed as one or more layers or coatings; Non-adjustable resistors made from powdered conducting material or powdered semi-conducting material with or without insulating material
  • H01C7/10—Non-adjustable resistors formed as one or more layers or coatings; Non-adjustable resistors made from powdered conducting material or powdered semi-conducting material with or without insulating material voltage responsive, i.e. varistors
  • H01C7/12—Overvoltage protection resistors

Definitions

• the invention relates to the overvoltage protection containing at least one non-linear resistance element, connection points for its connection to the protected circuit and a device for temperature initiated disconnection of a nonlinear resistance element from the protected circuit.
• the aim of the invention is to enable usage of the existing commercially available leadless materials as a substitution for solders with content of lead in overvoltage protections.
• the principle of invention has been achieved by an overvoltage protection, whose principle consists in that the device for temperature initiated disconnection of a non-linear resistance element from the protected circuit contains at least one by means of a heat of the non-linear resistance element disconnectable tight joint created parallel to the current-conductive track and made of leadless solder of required strength but of a worse electrical conductivity, further it contains at least by means of a heat of the non-linear resistance element disconnectable conductive joints created in the current- conductive track and made of low strength electrical conductive leadless solder.
• the invention is schematically shown in the drawing, where the Fig. 1 shows a schematic arrangement of one exemplary embodiment of a plug-in protective element, the Fig. 2 an example of embodiment of invention with a two stage signalling of status of overvoltage protection, the Fig. 3 an example of embodiment of invention with a three stage signalling of status of overvoltage protection, the Fig. 4 an example of embodiment of invention on overvoltage protection of another internal arrangement, the Fig. 5 an example of embodiment on overvoltage protection of another internal arrangement and the Fig. 6 an example of embodiment on overvoltage protection of another internal arrangement.
• overvoltage protections in the form of plug-in protective elements, which are in a replaceable manner mounted in the holder, which features a profile of at least approximately of the ,,U" letter.
• plug-in protective elements which are in a replaceable manner mounted in the holder, which features a profile of at least approximately of the ,,U" letter.
• the holder comprises clamps for attachment of electric conductors of protected circuit.
• the holder is provided with means for mechanical connection of the plug-in protective element and it also comprises means for electric connection of the plug-in protective element to the holder like the current lines and contacts etc.
• Overvoltage protection may be equipped with a remote and/or local signalling of status change.
• the cut- off device 3 of overvoltage protection from the protected circuit which is coupled with means for signalling the status change of overvoltage protection, which may be either the local and/or the distance ones.
• the lever 4 of visual signalling which is with its first end 40 coupled with the cut-off device 3 and with its second end 41. it is assigned to the window 10 of visual signalling in the body ⁇ .
• Both the local and the remote signalling may be created as a two-stage one when the functioning and defective status of overvoltage protection is signalled only, or as a three-stage when besides the functioning and defective status of overvoltage protection also the transition status is signalled, when the overvoltage protection is still functioning, nevertheless it is recommended to be replaced for a new one.
• stranded wire 5 may be modified to increase the rigidity, e.g. by welding the individual strands forming the stranded wire, by joining together the strands of the stranded wire 5 by means of a low-fusing leadless solder etc.
• the angle stop 6, against which the adjacent end 300 of spring-loaded shifting element 30 of the cut-off device 3 is leaning.
• one end of the stranded wire 5 by means of a low strength electrical conductive leadless solder is connected to the upper side of electrode 20 of varistor 2, while to the lower side of electrode 20 of varistor 2 by means of a leadless solder with required strength but worse electrical conductivity there is attached the angle stop 6, which extends from the outer side as far as behind the stranded wire 5 and the adjacent end 300 of the spring-loaded shifting element 30 of cut-off device 3 is leaning against the stranded wire 5, which is leaning against an arm of the angle stop 6.
• Low strength electrical conductive leadless solder at the same time does not transfer any mechanical load, it only serves to lead electric current between electrode 20 of varistor 2 and the wire 5.
• the not illustrated second electrode of varistor 2 is connected with the not illustrated another contact on opposite polarity, e.g. with a second contact of the plug-in protective element or a contact of another non-linear protective element at serial arrangement of nonlinear resistance elements etc.
• stranded wire 5 may be modified to increase rigidity, e.g. by welding individual strands forming the stranded wire, joining together the strands of stranded wire 5 by means of a low strength leadless solder etc.
• first leadless solder of required strength but worse electrical conductivity there is positioned the first angle stop 6, while on the first angle stop 6 by means of a second leadless solder with required strength but worse electrical conductivity there is positioned the second angle stop 7, against which the adjacent end 300 of the spring-loaded shifting element 30 of the cut-off device 3 is leaning.
• the first leadless solder with required strength but worse electrical conductivity has a higher melting temperature than the second leadless solder with required strength but worse electrical conductivity.
• Low strength electrical conductive leadless solder hereby does not transfer any mechanical load, it only serves to lead the electric current between electrode 20 of varistor 2 and the stranded wire 5.
• the not illustrated second electrode of varistor 2 is connected with the not illustrated second contact of the plug-in protective element or a contact of another non-linear protective element at serial arrangement of non-linear resistance elements etc. Also at the embodiment according to the Fig. 3 there may be created a structure, in which the end of the stranded wire 5 is positioned on the upper side of electrode 20 of varistor 2 and the angle stops 6, 7 are positioned on the lower side of electrode 20 of varistor 2.
• the device according to the embodiment shown in the Fig. 2 and 3 are functioning so that upon occurrence of overvoltage in the protected electric circuit the varistor 2 or varistors 2 representing the protective element are reducing this overvoltage to an admissible value. Due to ageing and overloading of individual components of the protective element (non-linear resistance element, varistor 2, group of varistors etc.) nevertheless the properties of the protective element are changing, resulting in that through the protective element (varistor 2) gradually flows an increased electric current, which causes heating-up of the protective element (varistor 2). Naturally, the thermal energy from the protective element (varistor 2) is conducted also to the electrode 20 of varistor 2, which is gradually becoming warmer.
• the second leadless solder of sufficient strength but worse electrical conductivity gets molten.
• the joint of the second angle stop 7 with the first angle stop 6 loses the ability to prevent the first displacement of the spring-loaded shifting element 30 of the cut-off device, which by its end 300 pushes off the second angle stop 7 to the first angle stop 6.
• the status signalling of overvoltage protection signal ises the change from the ,,fully functioning" status to the transition status".
• Further heating of electrode 20 of varistor 2 causes melting of the first leadless solder of a necessary strength but worse electrical conductivity and melting of the low strength electrical conductive leadless solder.
• the overvoltage protection has a different inner arrangement than the embodiment of the Fig. 1 to 3.
• the cut-off mechanism with three-stage status signalling of overvoltage protection here contains the spring 8, which acts to the ,,T" lever 80, which by its one arm 801 acts against the conductive connecting element 8J-.
• the connecting element 8I- is at its end 810 by means of the first low strength electrical conductive leadless solder 85 connected with the angle stop 84, which is by the second low strength electrical conductive leadless solder 83 connected with electrode 82 of the non-linear resistance element (varistor).
• the first low strength electrical conductive leadless solder 85 at the same time has a lower melting temperature than the second low strength electrically conductive leadless solder 83.
• the angle stop 84 is further with electrode 82 of the non-linear resistance element (varistor) and the end 810 of the connecting element 8J. connected by means of the first and the second leadless solder 820, 821 of required strength but worse electrical conductivity, e.g. this is realised in corners formed by the side walls of electrode 82 and the wall of angle stop 84 or the walls of the end 810 of the connecting element 81_ and a wall of the angle stop 84.
• the first leadless solder 820 of required strength but worse electrical conductivity has a lower melting temperature, than the second leadless solder 82J. of required strength but worse electrical conductivity.
• the second leadless solder 83 and the low strength electrical conductive leadless solder 820 are molten, whereby by acting of a spring 8 the lever 80 further turns and the connecting element 81 , and angle stop 84 are pushed off from electrode 82, through which the electrode 82 is disconnected from the contact 86 and the signalling end 802 of the lever 80 further shifts and signalises the status of overvoltage protection as ,,totally not functioning".
• the overvoltage protection is cut-off from the protected circuit.
• the overvoltage protection with three-stage status signalling contains the spring 9, which develops a constant pressure to the shifting electrical conductive connecting element 90.
• the connecting element 90 at its one end in electrically conductive manner is connected with the stranded wire 92 of one contact of the plug- inprotective element, and at its second end the connecting element 90 by means of thermal disconnectable joint using the low strength electrical conductive leadless solder in an electrically conductive manner is connected with electrode 9_1 of the non-linear resistance element (varistor).
• the connecting element 90 is with electrode 91.
• the embodiment according to the Fig. 5 may be simply adapted to an embodiment with two-stage status signalling of overvoltage protection, e.g. by omitting the angle stop 94 and the related elements.
• the device according to the embodiment in the Fig. 5 functions so, that through heating from electrode 91 at first the first leadless solder of required strength but worse electrical conductivity gets molten, due to that the conductive connecting element 90 by acting of the spring 9 shifts by a distance ⁇ to the stopper 96 of angle stop 94.
• the signal indicating the status of overvoltage protection transition status is initiated, e.g. the window of visual signalling shows a field of yellow colour on the conductive connecting element 90, while the electrical conductive connection of connecting element 90 and electrode 9J. remains preserved.
• the angle stop 94 releases from the contact 9_1 and the conductive connecting element 90 by acting of the spring 9 totally pushes off the electrode 9J. and the electrically conductive connection of electrode 91_ and of connecting element 90 is cut off, through which the overvoltage protection is disconnected from protected circuit and the signal indicating the status of overvoltage protection ..totally not functioning" is initiated e.g. the window of visual signalling shows a field of a red colour on the conductive connecting element 90.
• the overvoltage protection contains a spring 10, which constantly by tension acts upon the lever H, which acts upon the conductive stripe 12, which passes through a hole in electrode 13 of non-linear resistance element (varistor).
• the conductive stripe 12 in the initial status when the overvoltage protection is entirely intact, is attached by means of the first leadless solder 14 of required strength but worse electrical conductivity to electrode 13 of non linear resistance element (varistor).
• the conductive stripe 12 is provided with a stop being released by a heat 17, e.g.
• electrode 13 of non-linear resistance element is by a heat dependent joint in an electrically conductive manner connected with the conductive stripe 12, e.g. by means of electrically conductive connecting element 16, e.g. the conductive stranded wire, which is with electrode 13 and the conductive stripe 12 connected by means of a low strength electrically conductive leadless solder 160.
• the first leadless solder 14 of required strength but worse electrical conductivity has a lower melting temperature than the second leadless solder 15 of required strength but worse electrical conductivity.
• the first leadless solder 14 of required strength but worse electrical conductivity gets molten, and by acting of the spring 10 the lever 11 turns and pulls the conductive stripe 12 by the stop 17 towards electrode 13.
• the conductive stripe 12 is constantly in electrical conductive manner by means of connecting element 16 connected with electrode 13 of varistor.
• the signal on partial deterioration of overvoltage protection is established, e.g. the window of visual signalling shows a field of yellow colour on informative arm HO of the lever H, and possibly the signal for remote signalling is established.
• the arm H By another heating of electrode 13 the second leadless solder 15 with higher melting temperature gets molten, the arm H by acting of the spring tO further turns, the conductive stripe 12 is released from a hole in electrode 13; , and the connecting element 16 releases from electrically conductive connection with the conductive stripe 12 and/or electrode 13.
• the signal on total impairment of overvoltage protection is established, e.g. the window of visual signalling shows a field of red colour on informative arm 110 of the lever H, and possibly the signal for remote signalling is established.
• the common feature of above mentioned solutions is combination in using two types of solder, namely usage of leadless solder of required strength but worse electrical conductivity for joints requiring rigidity, and usage of a low strength electrical conductive leadless solder for joints requiring an electrical conductivity.
• the joints of parts, between which both the strength and electrical conductivity is required simultaneously are performed either by incorporating at least one auxiliary element, which enables creating the current-conductive track, and simultaneously production of a tight joint, or they are performed on one section of surfaces of both parts by means of a low strength electrical conductive leadless solder and on another section of surface of both parts by means of a leadless solder of required strength but worse electrical conductivity.
• the invention is not limited only to the expressly described or directly illustrated embodiments, as modification of a structural execution lies in the scope of mere specialised skill of an average specialist in this technical field.
• the invention is either not limited to the two-stage or only three-stage status signalling of overvoltage protection, respectively the plug-in protective element.
• the price available leadless solders of suitable electrical characteristics and mechanical properties it will be possible at the present as well as new structures to replace simply the solders with content of lead by new leadless solders or it will be possible to use the solution according to this invention.

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• Engineering & Computer Science (AREA)
• Microelectronics & Electronic Packaging (AREA)
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• 2007
  • 2007-02-28 CZ CZ20070167A patent/CZ2007167A3/cs unknown
  • 2007-03-27 EP EP07734081A patent/EP2132752A1/en not_active Withdrawn
  • 2007-03-27 WO PCT/IB2007/000752 patent/WO2008104824A1/en not_active Ceased

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