JP2008028088A - Lead wire lead-out type spd - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To very much simplify the connection between the external lead-out lead wire of an insulating cover, led out of a storage case for storing a zinc oxide type varistor and a lead-out conductor in the storage case, and to connect them with continuously stable, high mechanical strength. <P>SOLUTION: A first hole 31 for leading out a lead wire is formed at the storage case 30 for storing the zinc oxide type varistor 1, and a second hole 32 for connecting a lead-out conductor are formed while the second hole 32 crosses the first hole 31. An insulating cover edge 20' in the external lead-out lead wire 20 is inserted into the first hole 31, the linear tip section of the drawing-out conductor 13 is inserted into the second hole 32, and by making the tip stuck to the insulating cover edge 20' penetrate, to electrically and mechanically connect it to the lead wire 20. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a lead wire drawing type SPD (Surge Protective Device) using an insulated wire from a storage case storing a zinc oxide type varistor.

  For the purpose of preventing lightning damage, an SPD is installed as a device that shunts a surge current by limiting a transient overvoltage caused by lightning between an electric device and the ground in a single-phase or three-phase AC circuit or DC circuit. As this SPD element, a zinc oxide varistor is generally used.

  A zinc oxide type varistor is a rectangular or disc-shaped plate-like lightning protection element mainly composed of ZnO, and electrodes are attached in a thin plate shape on both front and back surfaces. The zinc oxide type varistor has a characteristic that the resistance changes according to the voltage applied between the electrodes on the front and back surfaces, that is, extremely high resistance when a voltage equal to or lower than the threshold voltage is applied, and substantially exhibits insulation. When a voltage exceeding the threshold voltage is applied, it has a non-linear current-voltage characteristic indicating low resistance.

  In general, an SPD using a zinc oxide varistor is configured by combining a zinc oxide varistor with other SPD elements such as a discharge fuse, a thermal fuse for protecting an SPD, and a current fuse. When a lightning surge is repeatedly input, the zinc oxide varistor deteriorates with time depending on the input level, and the leakage current increases to generate heat, which may cause smoke and ignition due to thermal runaway. Therefore, in SPD, as a protection means for preventing smoke and ignition due to thermal runaway of a zinc oxide varistor, a temperature fuse that operates by disconnection due to heat generation due to varistor deterioration is integrally assembled with the zinc oxide varistor (for example, Patent Document 1).

SPDs using zinc oxide type varistors house multiple types of SPD elements, including zinc oxide type varistors, in a plastic insulating storage case, and the SPD elements are protected electrically and mechanically by the storage case. is doing. The electrode of the SPD element including the zinc oxide varistor stored in the storage case is drawn out of the case using a plurality of types of conductors such as a metal wire, a metal plate lead conductor, and an external lead wire. (For example, see Patent Document 2).
JP 2003-229303 A JP 2001-297904 A

  The SPD in which the lead wire of the insulated wire is drawn out from the storage case constitutes the SPD circuit by connecting the electrode of the SPD element and the external lead wire in the storage case with a metal wire or a metal plate lead conductor. . The connection between the lead conductor, the SPD element, and the external lead wire is performed by various simple methods such as soldering, caulking, and crimping. It required considerable man-hours. Further, in addition to the connection method such as soldering, the step of stripping and man-hours for removing the insulating coating at the tip of the external lead wire and exposing the conductor are required, making it difficult to reduce the SPD manufacturing cost. Furthermore, when the external lead wire is pulled out of the storage case, the lead wire is required to withstand a tensile load of several kg from the viewpoint of reliability. In order to satisfy this requirement, there is a problem that the lead wire is directly supported by the storage case by bending the tip of the external lead wire in the storage case, resulting in a complicated configuration.

  The present invention has been made in view of the above-mentioned problems, and the object of the present invention is to simplify the connection between an external lead wire drawn out from a storage case for storing a zinc oxide varistor and a lead conductor in the storage case. Another object of the present invention is to provide a lead wire lead-out type SPD that can be connected with stable and high mechanical strength.

  The technical means for achieving the above object of the present invention is an SPD in which an insulated wire for an external lead wire and a lead conductor of the SPD element are connected in a storage case containing an SPD element including a zinc oxide varistor. The storage case includes a first lead wire lead hole into which the insulating coating end of the lead wire is inserted, and a lead conductor connecting portion into which the leading end of the lead conductor is inserted by partially opening into the first hole. The lead wire and the lead conductor are electrically connected by passing the tip of the lead conductor inserted in the second hole through the local part of the insulating coating end of the lead wire inserted in the first hole. It is characterized by mechanical and mechanical connection.

  Here, an insulating case made of resin can be applied as the storage case. The SPD element including the zinc oxide varistor stored in the storage case includes a zinc oxide varistor alone and other types of SPD elements other than the zinc oxide varistor and the zinc oxide varistor. Other SPD elements other than zinc oxide varistors include discharge gaps (discharge gap parts that have been commercialized), temperature fuses that are formed integrally with zinc oxide varistors, and zinc oxide varistors separately from zinc oxide varistors. These are temperature fuses, current fuses, etc. wired to varistors. When a plurality of SPD elements are stored in the storage case, the lead conductors of all the plurality of SPD elements are connected to the corresponding external lead wires, or a selected one of the plurality of SPD elements. Only the lead conductor is connected to the corresponding external lead. According to the present invention, the storage case includes a first hole and a second hole having a structure in which the lead conductor corresponding to the external lead wire is passed through and electrically and mechanically connected.

  The first hole of the storage case is a linear insertion hole into which the insulating coating end of the external lead wire that is an insulated wire can be inserted and removed in the axial direction. The insulation coating end portion of the external lead wire is an end portion with no insulation coating stripping allowance, and the entire outer periphery of the linear conductor (copper wire, annealed copper wire, etc.) is covered with an insulation coating material such as a resin material. The front end of the first hole is a closed end, and the insulating coating end portion of the lead wire is inserted until it comes into contact with the closed end. The second hole opens at a predetermined location away from the tip of the first hole. The second hole is a linear insertion hole that intersects the first hole at a right angle or at a predetermined crossing angle. From the end of the second hole opposite to the first hole, the straight end portion of the lead conductor is removably inserted into the second hole. After inserting the insulating coating end of the lead wire into the first hole, the leading end of the lead conductor is inserted into the second hole. When the leading end of the lead conductor is a sharp end and this sharp end is inserted from the second hole into the first hole, the sharp end pierces a part of the outer periphery of the end portion of the lead wire insulation coating inserted into the first hole. , Through the insulation coating and conductor. Depending on the material of the insulating coating of the lead wire, a method of drilling so as to remove in advance the portion where the lead conductor of the insulating coating pierces may be used. The leading end portion of the lead conductor penetrates a part of the insulating coating end portion of the lead wire, whereby both are electrically and mechanically connected. The electrical connection state between the two due to the piercing penetration is not stable as compared with other methods such as soldering and caulking, but there is no problem in the SPD corresponding to the lightning surge for the reason described later. Due to the structure in which the lead conductor of the second hole intersects and penetrates the lead wire of the first hole, the mechanical connection between them is always firmly performed, and a load is applied in the direction of drawing out the lead wire from the first hole. When hooked, the leading end of the lead conductor is locked in the second hole, the tensile load of the lead wire is always increased to several kg or more, and the mechanical reliability of the lead wire lead-out type SPD is improved.

  In the present invention, the angle between the insulation coating end of the lead wire inserted into the first hole of the storage case and the leading end of the lead conductor inserted into the second hole is a right angle, or the lead in the first hole It is desirable to make an acute angle with respect to the drawing direction. The acute angle here is an angle of 45 ° to 90 °. With this kind of crossing angle, when a load is applied in the direction in which the lead wire is pulled out from the first hole, the leading end of the lead conductor bites into the lead wire, and the tensile load of the lead wire is reduced. Make it stronger and more stable.

  In the present invention, a wire rod having a sharp tip can be applied to the lead conductor. A commercially available and inexpensive bare electric wire can be used as the lead conductor of the wire. In addition, a round hole with good workability can be applied to the second hole of the storage case corresponding to the lead conductor of the wire, and it becomes easy to insert the lead conductor into the second hole.

  Moreover, in this invention, the back of the 1st hole of a storage case can be made into the closed end which the front-end | tip of the external drawer lead wire inserted in the 1st hole abuts.

  The closed end at the back of the first hole here can be constituted by the side wall of the storage case. The insulated lead wire for the external lead-out lead wire is inserted into the first hole and positioned until the tip of the insulated wire comes into contact with the closed end of the first hole. As a result, the insertion amount of the lead wire into the first hole is constant, and electrical and mechanical connection with the lead conductor inserted from the second hole can be performed satisfactorily. Also, the tip of the lead wire inserted into the first hole is exposed at the tip (cut surface) of the conductor covered with the insulation coating, but this conductor tip surface is insulated and protected at the closed end of the first hole. It does not come out of the outer surface of the storage case, and the insulation measure of the lead wire lead-out type SPD becomes easy.

  According to the present invention, a one-touch type simple operation of piercing the leading end of the lead conductor inserted into the second hole of the storage case with respect to the insulated wire of the external lead wire inserted into the first hole of the storage case Electrical and mechanical connection between the lead wire and the lead conductor is possible, so even if there are many connection points between the lead wire and the lead conductor, it can be connected with less man-hours and working time, reducing the man-hours for SPD manufacturing and assembly. And the outstanding effect of facilitating the reduction of manufacturing and assembling costs is achieved. Also, since the insulation coating end of the external lead wire is inserted into the first hole and the lead conductor is pierced and penetrated, there is no need for stripping work to remove all the insulation coating of the insulation coating end of the lead wire. By reducing the number of connection steps, the workability of SPD manufacturing and assembly can be improved.

  In addition, since the leading end of the lead conductor inserted into the second hole intersects and penetrates the external lead wire inserted into the first hole of the storage case, a load is applied in the direction of pulling out the lead wire from the first hole. When hooked, the leading end of the lead conductor is locked in the second hole, and the lead wire can always have a large tensile load of several kg or more. A highly reliable lead wire lead type with stable mechanical strength. SPD can be provided.

  FIGS. 1 and 2 show the main configuration of a lead wire lead-out type SPD according to the first embodiment, and FIG. 3 shows an equivalent circuit. The lead wire SPD shown in FIG. 1 includes a zinc oxide varistor 1 mainly composed of ZnO and a discharge gap 2 connected to an electrode 12 on the back side of the zinc oxide varistor 1. Two types of SPD elements, the zinc oxide varistor 1 and the discharge gap 2, are stored in a common storage case 30. The zinc oxide varistor 1 is a lightning protection element having a rectangular flat plate shape that is applied to a single-phase three-wire or three-phase three-wire AC circuit, and has line-phase three electrodes 11,. The back surface side electrode 12 is a common electrode facing all of the front surface side three electrodes 11. The shape of the zinc oxide type varistor 1 is not limited to a rectangular shape, and may be a disc shape. The storage case 30 is an insulating case made of resin, and a total of four external lead wires 20 are drawn in parallel from the storage case 30 to constitute a lead wire lead-out type SPD.

  Each of the surface side three electrodes 11 of the zinc oxide type varistor 1 is connected to the lead conductors 13 by solder 5. These three lead conductors 13,... Are bare wire wires, and their tip portions are electrically and mechanically connected to the corresponding lead wires 20,. One lead conductor 14 is drawn out from the discharge gap 2 connected to the common electrode 12 of the zinc oxide type varistor 1 and is electrically and mechanically connected to the corresponding one lead wire 20.

  The storage case 30 is a rectangular box-shaped two-part case, and includes a main body 30a and a lid 30b. The main body 30a has a rectangular box shape with a bottomed upper end opening, and has four lead wire drawing first holes 31 parallel to the bottom. Each of the first holes 31 is linear, and one insulating coating end portion 20 ′ of each of the external lead wires 20 with insulating coating is inserted in a removable manner. A varistor positioning and holding rib 30c and a second hole forming cylinder 30d are formed in the internal space of the main body 30a. The zinc oxide varistor 1 is positioned and placed on the rib portion 30c with the common electrode 12 on the back side thereof facing down. The discharge gap 2 connected to the common electrode 12 of the zinc oxide varistor 1 by soldering or the like is installed in the space between the bottom of the main body 30a and the zinc oxide varistor 1. A second hole forming cylinder 30d is formed corresponding to the three electrodes 11,... On the surface of the zinc oxide varistor 1 positioned and mounted on the rib 30c. The second hole forming cylinder portions 30d are columnar cylinders protruding directly above the corresponding first holes 31, and each of the second hole forming cylinder portions 30d penetrates the second hole 32 in the axial direction. The second hole 32 is a straight through hole into which one of the lead conductors 13 of the wire is inserted so as to be detachable, and intersects the corresponding first hole 31.

  As shown in FIGS. 5 (A) and 5 (B), the tip of the first hole 31 is closed by the side wall of the storage case 30, and the insulation coating end 20 ′ of the lead wire 20 reaches the position where it comes into contact with the closed end. Inserted. The tip (lower end) of the second hole 32 opens at one place away from the closed end of the first hole 31 by about 5 mm. A small hole 33 as an extension hole of the second hole 32 is formed at the bottom of the first hole 31. The small hole 33 shown in FIG. 5 penetrates the bottom plate of the storage case 30, but may be a bottomed concave hole that does not penetrate.

  The lead wire lead-out type SPD of the above embodiment can be manufactured and assembled as follows. As shown in FIG. 4, the lid 30b is opened from the main body 30a of the storage case 30, and the lead wire 20 of the insulated wire corresponding to the first hole 31 at the bottom of the main body 30a is inserted. The lead wire 20 is formed by coating the outer periphery of a single conductor 20a with an insulating coating material 20b, so that the insulating coating end portion 20 'from which the insulating coating material 20b has not been peeled is lightly press-fitted into the corresponding first hole 31. Inserted. As shown in FIG. 5A, the lead wire 20 is inserted until the end of the insulating coating end portion 20 ′ contacts the closed end of the first hole 31. Such lead wire insertion can be sequentially performed on the four lead wires 20... Or can be performed simultaneously using a jig (not shown). After inserting the lead wire, as shown in FIG. 4, the varistor 1 with a lead conductor is assembled to the main body 30 a of the storage case 30, and at this time, the lead conductor 13 extending from the varistor 1 is inserted into the corresponding second hole 32.

  As shown in FIG. 5B, the leading end of the wire lead conductor 13 is sharpened and the leading end is inserted into the second hole 32 to insulate the lead wire 20 in the first hole 31 from the second hole 32. It penetrates in the direction crossing the covering end 20 ′. The leading end of the lead conductor 13 reaches the first hole 31 without being deformed by being guided by the second hole 32, and the sharp end is directly pierced into the insulating coating material 20 b of the insulating coating end 20 ′. The small hole 33 is reached through the conductor 20a. The leading end portion of the lead conductor 13 penetrates the conductor 20a of the lead wire 20, whereby both are electrically and mechanically connected, and the connection work is completed. Such a connection operation can be performed sequentially or simultaneously with respect to the three lead conductors 13,... Using a jig (not shown). Further, the lead wires corresponding to the lead terminals 14 of the discharge gap 2 can be connected in the same manner as described above. Such connection work can be done by simply inserting the lead wire into the first hole and inserting the lead-out terminal into the second hole, greatly reducing the number of SPD manufacturing and assembly steps, and reducing assembly time. It becomes easy to shorten.

  5B, when the leading end of the lead conductor 13 is passed through the lead wire 20, the sharp end of the lead conductor 13 may protrude from the small hole 33 on the bottom of the storage case 30. The sharp end protruding in this way is cut with a blade or the like, and an insulating seal 35 such as a name plate is attached to the back surface of the storage case 30 as shown in FIG. Alternatively, the small holes 33 may be filled with an insulating material, and the small holes 33 may be insulated and sealed. As described above, if the small hole 33 is formed into a concave hole with a bottom so that the sharp end of the lead conductor 13 does not protrude outside the case, the special insulation measures as described above are unnecessary.

  When the lead conductors 13 are passed through the corresponding lead wires 20 and the two conductors are electrically and mechanically connected, the electrical connection state is not stable, and there is a possibility that the contact failure and the electrical connection failure of both conductors may occur. is there. However, when it is used as an SPD (lightning surge protection device) element, there is no problem because the defective electrical connection operates as a discharge gap. In other words, a large surge voltage is applied to the poorly connected part during SPD operation, and a large current flows for a very short time of several tens of μs. Therefore, even if the contact resistance is increased due to the oxide film, the oxide film is generated with a large surge voltage. This has the effect of destroying and not reducing the reliability.

  Further, the lead conductors 13 are passed through the corresponding lead wires 20 to mechanically connect the two conductors, so that the mechanical strength is large and stable. As shown in FIG. 5B, when the crossing angle between the first hole 31 and the second hole 32 is θ, this crossing angle θ is relative to the lead-out direction X of the lead wire 20 inserted into the first hole 31. Set to right angle or acute angle. When a tensile load is applied to the lead wire 20 in the lead-out direction X, the leading end portion of the lead conductor 13 that penetrates the lead wire 20 is locked in the second hole 32, and the tensile load necessary for the lead wire 20 is set large. be able to. Such a tensile load can be effectively increased when the crossing angle θ is a right angle or an acute angle close to a right angle.

  Next, a second embodiment of the present invention will be described with reference to FIGS. 6 and 7 show the configuration of the main part of the lead wire lead-out type SPD of the second embodiment, and FIG. 8 shows an equivalent circuit. The lead wire lead-out type SPD in the figure has a thermal fuse function in each of the lead conductors 13 corresponding to the three electrodes 11 of the zinc oxide type varistor 1, and the thermal fuse operation is visually recognized by heat generation due to deterioration of the varistor 1. A display 40 is provided.

  The lead conductor 13 is a wire, and the tip portion is inserted into the corresponding second hole 32 and penetrates the lead wire 20. A middle portion of the rear end portion of the lead conductor 13 is joined to the corresponding electrode 11 of the zinc oxide varistor 1 with a low melting metal alloy 41. The low melting metal alloy 41 is a low melting point alloy that melts due to heat generated by excessive surge degradation of the varistor 1. The rear end portion of the lead conductor 13 protrudes rearward from the low melting metal alloy 41, and the display plate 42 is fixed to the front end thereof. A display window 43 is formed in a portion of the storage case 30 that faces the display plate 42. The display panel 42 and the display window 43 constitute one display 40. One such indicator 40 is installed on each of the lead conductors 13 corresponding to the three electrodes 11 of the zinc oxide varistor 1.

  The lead conductor 13 shown in FIG. 6 has a spring force in which the rear end portion is separated from the electrode 11 of the zinc oxide type varistor 1 by melting the low-melting metal alloy 41 due to abnormal heat generation due to deterioration over time of the zinc oxide type varistor 1. Have Strictly speaking, at the time of softening before the low-melting metal alloy 41 is completely melted, the lead conductor 13 is displaced by its spring restoring force, and the thermal fuse is blown, resulting in the state of FIG. FIG. 7 shows a state in which the lead conductor 13 is displaced from the front end inserted into the second hole 31 as a base point, and the display plate 42 at the rear end moves. The display surface of the display plate 42 is set to have an area that is at least twice that of the display window 43, and the display plate 42 is displaced so that half of the color of the display surface faces the display window 43. Then, by distinguishing the color of the display plate 42 from the display window 43, it can be recognized at a glance whether it is a normal state of FIG. 6 or an abnormal state of FIG.

  The zinc oxide type varistor in the lead wire lead-out type SPD described above is a three-phase multi-terminal varistor in which three electrodes are formed on the front side and a common electrode is formed on the back side, but the present invention is not limited to this. A two-terminal varistor in which a pair of electrodes are formed on the front and back surfaces of a zinc oxide varistor is also applicable.

It is a side view including the partial cross section which shows the principal part structure of the lead wire drawer | drawing-out type SPD of the 1st Embodiment of this invention. It is a front view including the partial cross section of SPD of FIG. It is an equivalent circuit of SPD of FIG. It is a disassembled side view at the time of manufacture and assembly of SPD of FIG. FIG. 1A is a partially enlarged cross-sectional view of FIG. 1 SPD during manufacturing and assembly, and FIG. 1B is a partially enlarged cross-sectional view of when two conductors are connected. It is a side view including the partial cross section which shows the principal part structure of the lead wire drawer | drawing-out type SPD of the 2nd Embodiment of this invention. FIG. 7 is a side view including a partial cross section during thermal fuse operation of the SPD of FIG. 6. It is an equivalent circuit of SPD of FIG.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Zinc oxide type varistor, SPD element 2 Discharge gap, SPD element 11, 12 Electrode 13.14 Lead conductor 20 Lead wire 20 'Insulation coating end 20a Conductor 20b Insulation coating 30 Storage case 30a Main body 30b Lid 31 First hole 32 Second hole 33 Small hole 40 Display 41 Low molten metal alloy 42 Display panel 43 Display window θ Crossing angle X Lead wire drawing direction

Claims (4)

An SPD in which an insulated lead wire for an external lead wire and a lead conductor of the SPD device are connected in a storage case containing a SPD device containing a zinc oxide varistor,
The storage case includes a lead wire lead-out first hole into which an insulating coating end portion of the lead wire is inserted, and a lead conductor connection in which the leading end portion of the lead conductor is inserted by being partially opened in the first hole. A lead hole inserted into the first hole and intersected with a tip of the lead conductor inserted into the second hole at a local portion of the insulating coating end portion of the lead wire inserted into the first hole. A lead wire lead-out type SPD in which a wire and a lead conductor are electrically and mechanically connected.   The angle between the end portion of the insulation coating of the lead wire inserted into the first hole and the leading end portion of the lead conductor inserted into the second hole is perpendicular or relative to the lead wire drawing direction in the first hole. The lead wire lead-out type SPD according to claim 1, which has an acute angle.   The lead wire lead-out type SPD according to claim 1 or 2, wherein the lead conductor is a wire rod having a sharp tip.   The lead wire lead-out type SPD according to any one of claims 1 to 3, wherein a depth of the first hole is a closed end against which a tip of the lead wire inserted into the first hole abuts.

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