JP2011233819A - Lightning arrestor and method for manufacturing the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a lightning arrestor which is excellent in mechanical strength, improves assembly workability, and by which cost reduction is attained.SOLUTION: The lightning arrestor comprises: a series body 1b including a zinc oxide element block 1a in which a plurality of zinc oxide elements 1 are laminated in the axial direction, and a pressure spring 2 arranged at one end of the zinc oxide element block 1a; a pair of terminal electrodes 3a and 3b which sandwich the series body 1b in the axial direction; a plurality of insulation rods 4 which are arranged along the axial direction in the surroundings of the series body 1b to fix the pair of terminal electrodes 3a and 3b at a state that a predetermined axial direction load is energized; and silicone rubber 7 which coats the surroundings of an internal element 1c including the series body 1b and the insulation rods 4 to be integrated. To the pair of terminal electrodes 3a and 3b, a plurality of rod mounting holes 32 into which the ends of the insulation rods 4 are inserted are bored, and in each insulation rod 4, both ends are penetrated into the insulation rod mounting holes 32, the pair of terminal electrodes 3a and 3b and each insulation rod 4 are molded by resin to be fastened.

Description

  The present invention laminates a plurality of zinc oxide elements that protect against abnormal voltages such as switching surges and lightning surges that occur in circuits of electrical equipment connected to the power system, and insulates them with silicone rubber or organic insulators, etc. The present invention relates to a lightning arrester covered with a material as a jacket and a method for manufacturing the same.

  Power facilities such as power plants and substations are required to have excellent seismic performance from the concept of safe power supply. Currently, insulator-type lightning arresters using porcelain insulators are the mainstream in air-insulated lightning arresters, but lightning arresters that directly mold internal elements including zinc oxide elements with silicone rubber are smaller and lighter than insulator-type lightning arresters. In recent years, its application has been expanding overseas due to its excellent seismic performance and arc resistance.

  The basic structure of a lightning arrester in which an insulating material such as silicone rubber or an organic insulator is covered around a zinc oxide element is an insulating rod such as FRP (Fiber Reinforced Plastics) around the laminated zinc oxide element. The insulator is fixed with terminal electrodes placed on both ends of the zinc oxide element. In the lightning arrester having such a structure, since the insulating material such as silicone rubber or organic insulator itself does not have sufficient rigidity, an insulating rod such as FRP provides mechanical strength as a lightning arrester. Conventionally, as a technique for fixing the terminal electrode and the insulating rod, there is, for example, the following Patent Document 1.

  In the technique disclosed in Patent Document 1, an insulating rod is inserted into each rod mounting hole of the terminal electrode, and in a state where tensile stress is applied to the insulating rod, each rod mounting hole is crimped to crimp the electrode and the insulating rod. And a technique for fixing them.

JP 2002-270406 A

  However, in the technique disclosed in Patent Document 1, since the tensile force in the direction in which the caulking is removed is received by the frictional force between the insulating rod and the terminal electrode, the fixing between the insulating rod and the electrode may be loosened. In order to prevent the insulation rod from coming off, there is a problem that it is necessary to apply an adhesive to the caulking portion in advance, which increases the number of assembly steps and takes time for assembly.

  In addition, as a method of fixing the insulating rod and the electrode, there is a method in which a stopper mounting hole is provided in the electrode and the insulating rod and fixed with a bolt, a screw, or the like. In many cases, the mechanical strength decreases. In addition, parts such as bolts and screws are necessary, and an operation of tightening those bolts and screws is necessary. Therefore, there is a problem that the cost is high and the number of assembling steps is increased.

  The present invention has been made in view of the above, and an object of the present invention is to obtain a lightning arrester that is excellent in mechanical strength, improves assembly workability, and realizes cost reduction.

  In order to solve the above-described problems and achieve the object, the present invention has a voltage non-linear resistor block in which a plurality of voltage non-linear resistors are stacked in the axial direction and one end of the voltage non-linear resistor block. A series body including a pressing spring, a pair of terminal electrodes sandwiching the series body in the axial direction, and arranged around the series body along the axial direction. The pair of terminal electrodes are subjected to a predetermined axial load. A plurality of insulating rods that are fixed in a biased state, and an insulating jacket that covers and integrates the periphery of an internal element that includes the series body and the insulating rod, and the pair of terminal electrodes includes: A plurality of insulating rod mounting holes for inserting the end portions of the insulating rods are perforated, the insulating rods have both end portions penetrated through the insulating rod mounting holes, and the pair of terminal electrodes and the insulating rods are made of resin. That it is molded and fixed And butterflies.

  According to the lightning arrester of this invention, it is excellent in mechanical strength, and there exists an effect that cost reduction can be implement | achieved while improving assembly workability | operativity.

FIG. 1 is a vertical cross-sectional view illustrating a configuration example of a lightning arrester according to an embodiment. FIG. 2 is an assembly exploded longitudinal sectional view illustrating an example of a procedure for assembling the lightning arrester according to the embodiment using an assembly jig. FIG. 3 is a comparison diagram between the case where the end of the insulating rod is resin-molded and the case where it is crimped with a crimping fitting.

  Hereinafter, a lightning arrester according to an embodiment of the present invention will be described in detail with reference to the accompanying drawings. The present invention is not limited to the following embodiments.

Embodiment.
FIG. 1 is a vertical cross-sectional view illustrating a configuration example of a lightning arrester according to an embodiment. As shown in FIG. 1, a zinc oxide element block 1a in which a plurality of zinc oxide elements 1 functioning as voltage nonlinear resistors are stacked is disposed at the center. The zinc oxide element block 1a is disposed with one end of the pressing spring 2 in a contracted state, and the zinc oxide element block 1a and the pressing spring 2 constitute a series body 1b. A lower terminal electrode 3a is disposed below the series body 1b, and an upper terminal electrode 3b is disposed above the plurality of insulating rods disposed around the series body 1b between the lower terminal electrode 3a and the upper terminal electrode 3b. 4 is bridged. Hereinafter, the stacking direction of the voltage nonlinear resistors is referred to as “axial direction”.

  In the lower terminal electrode 3a and the upper terminal electrode 3b, a plurality of insulating rod mounting holes 32 for inserting the insulating rod 4 around the series body 1b are perforated through the same circumference in parallel with the axial direction. Yes. The inner diameter of the insulating rod mounting hole 32 is slightly larger than the diameter of the insulating rod 4 from the joint surface side of the lower terminal electrode 3a and the upper terminal electrode 3b contacting the series body 1b to a predetermined position. This portion is hereinafter referred to as a “small diameter portion”. On the other hand, the inner diameter after a predetermined position from the joining surface is formed larger than the inner diameter on the joining surface side. This portion is hereinafter referred to as “large diameter portion”. A locking groove 33 is formed in the circumferential direction in the small diameter portion of the insulating rod mounting hole 32, and an O-ring 5 having an inner diameter slightly smaller than the diameter of the insulating rod 4 is disposed in the locking groove 33. Yes. A resin injection hole 34 is drilled in the large diameter portion of the insulating rod mounting hole 32 of the upper terminal electrode 3b perpendicular to the axial direction.

  The end portion of the insulating rod 4 is inserted from the small diameter portion of the insulating rod mounting hole 32, passes through the O-ring 5, and protrudes from the large diameter portion of the insulating rod mounting hole 32. The casting resin 6 is injected between the protruding portion and the large diameter portion of the insulating rod mounting hole 32, and the terminal electrodes 3a and 3b and the insulating rod 4 are fixed. In addition, as a material of the casting resin 6, an epoxy resin or a urethane resin is suitable, for example. The O-ring 5 prevents the casting resin 6 from leaking from the gap between the small diameter portion of the insulating rod mounting hole 32 and the insulating rod 4 when the casting resin 6 is injected. In addition, when the viscosity of the casting resin 6 is high, the casting resin 6 is not likely to leak from the gap between the small diameter portion of the insulating rod mounting hole 32 and the insulating rod 4, or the casting resin 6 can be allowed to leak. In such a case, the O-ring 5 and the locking groove 33 can be omitted. Then, the lightning arrester according to the embodiment is configured by being integrated by molding with silicone rubber 7 functioning as an insulating jacket so as to cover the periphery of the internal element 1c including the series body 1b and the insulating rod 4. ing.

  Next, an assembly jig used when assembling the lightning arrester according to the embodiment will be described with reference to FIG. FIG. 2 is an assembly exploded longitudinal sectional view illustrating an example of a procedure for assembling the lightning arrester according to the embodiment using an assembly jig. Here, the height of the lightning arrester including the terminal electrodes 3a and 3b in the axial direction is defined in a state where a predetermined axial load is applied. That is, the length at which both end portions of the insulating rod 4 protrude from the large diameter portion of the insulating rod mounting hole 32 is defined in a state where a predetermined axial load is applied. Therefore, as shown in FIG. 2, the assembling jig 8 has an interval obtained by adding the height of the lightning arrester, the height of the jack 9 and the thickness of the auxiliary plate 8d defined in a state where the predetermined axial load is applied. The upper and lower plates 8a and 8b are opposed to each other and fixed by a plurality of support bars 8c.

  The process of assembling the lightning arrester according to the embodiment using the assembly jig 8 will be described. First, one end of each insulating rod 4 is inserted into each insulating rod mounting hole 32 of the lower terminal electrode 3a, and one end portion of each insulating rod 4 having a predetermined length protrudes from the large diameter portion of the insulating rod mounting hole 32; The casting resin 6 is injected so that the opening on the large diameter side of each insulating rod mounting hole 32 of the lower terminal electrode 3a is on top, and one end of each insulating rod 4 and the lower terminal electrode 3a are resin-molded. To fix. Next, the lower terminal electrode 3a to which each insulating rod 4 is fixed is placed on the lower plate 8a of the assembly jig 8 so that the other end of each insulating rod 4 faces upward. A zinc oxide element block 1a in which the zinc oxide elements 1 are laminated is disposed between the insulating rods 4 on the lower terminal electrode 3a, and a pressing spring 2 is disposed on the upper part to constitute a serial body 1b. Furthermore, the upper terminal electrode 3b is arrange | positioned so that the other end of each insulation rod 4 may be inserted in each insulation rod attachment hole 32 of the upper terminal electrode 3b in the upper part. In the example shown in FIG. 2, the lower plate 8a is provided with a plurality of protrusions whose relative positions coincide with the respective insulating rod mounting holes 32 of the lower terminal electrode 3a, and the plurality of protrusions and the lower terminal electrode 3a. The dry surface of the casting resin 6 injected into each of the insulating rod mounting holes 32 is held in contact with each other, but no protrusion is provided, and the lower plate 8a and the lower terminal electrode 3a are directly contacted. You may make it hold | maintain.

  Next, the auxiliary plate 8d and the jack 9 are inserted between the upper terminal electrode 3b and the upper plate 8b, and a predetermined axial load is applied by the jack 9. As described above, the height in the axial direction of the lightning arrester including the terminal electrodes 3a and 3b is defined in a state where a predetermined axial load is applied. Therefore, when a predetermined axial load is applied by the jack 9, the other end portion of each insulating rod 4 having a predetermined length protrudes from the large diameter portion of the insulating rod mounting hole 32. The casting resin 6 is injected from the resin injection hole 34 between the protruding portion and the large diameter portion of the insulating rod mounting hole 32, and the upper terminal electrode 3b and each insulating rod 4 are fixed. In FIG. 2, the casting resin 6 is injected from the resin injection hole 34 drilled in the large diameter portion of the insulating rod mounting hole 32 of the upper terminal electrode 3b, but the resin injection hole is provided in the auxiliary plate 8d. It is also possible to provide it. Moreover, when the axial load by the jack 9 is stably applied, the auxiliary plate 8d may not be provided.

Next, the mechanical strength of each terminal electrode 3a and 3b and each insulating rod 4 of the lightning arrester according to the embodiment will be described with reference to FIGS. As shown in FIG. 1, when the diameter of the insulating rod 4 is D = 10 (mm), and the length at which both ends of the insulating rod 4 protrude from the large diameter portion of the insulating rod mounting hole 32 is l = 10 (mm). The resin fixing area A in the circumferential direction of the insulating rod 4 is
A = πDl≈314.1 (mm ² ) (1)
It becomes. When the number of the insulating rods 4 is n = 4 and an axial load of F1 = 1000 (N) is applied by the jack 9 during assembly, the stress σ1 applied to each insulating rod 4 in the steady state after assembly is ,
σ1 = F1 / (A * n) = 1000 / (314.1 * 4) ≈0.8 (N / mm ² )
... (2)
It becomes.

On the other hand, when a bending load of F2 = 1000 (N) is applied perpendicular to the axial direction, if the distance between the terminal electrodes 3a and 3b is L = 375 (mm), the moment M received by the lightning arrester is
M = F2 * L = 1000 * 375 = 375000 (N · mm) (3)
When the distance from the central axis to each insulating rod 4 is r = 17.5 (mm), the tensile load f acting on each insulating rod 4 is
f = M / (r * n) = 375000 / (17.5 * 4) ≈5360 (N)
... (4)
It becomes. At this time, the stress σ2 applied to one insulating rod 4 is
σ2 = f / A = 5360 / 314.1≈17.06 (N / mm ² ) (5)
Thus, a stress of about 20 times or more of the stress σ1 applied in the steady state is applied. That is, as the mechanical standard value of the lightning arrester, when a bending load of F2 = 1000 (N) is necessary, the stress σ2 shown in the equation (5) is the allowable stress per one of the insulating rods 4, that is, The stress is to be allowed per one insulating rod 4.

  FIG. 3 is a comparison diagram between the case where the end of the insulating rod is resin-molded and the case where it is crimped with a crimping fitting. As shown in FIGS. 3 (a) and 3 (b), in each case, the diameter of the insulating rod is D = 10 mm, the length of the resin fixing portion and the portion crimped with the crimping fitting is l = 10 mm, An example in which a punching load is applied in the direction of the arrow in the middle is shown. FIG. 3C shows the ultimate stress for each of the five samples and the average value of the ultimate stress of each of the five samples in the example shown in FIG. 3A and FIG. Here, the ultimate stress indicates an extreme stress that does not cause deformation or destruction of the caulking portion by the resin mold portion or the crimp fitting.

  As shown in FIG. 3C, the ultimate stress when the end of the insulating rod is caulked with a crimping fitting does not reach the allowable stress σ2 shown in equation (5), and the safety factor (= ultimate stress) / Allowable stress) is about 0.2 to 0.3. That is, the mechanical strength is insufficient with respect to the bending load of F2 = 1000 (N) only by crimping one end of the insulating rod with the crimping fitting.

  On the other hand, the ultimate stress when the end of the insulating rod is resin-molded satisfies the allowable stress σ2 shown in the equation (5) in all samples, and the safety factor is about 2.0 to 2.4. In other words, when the end of the insulating rod is resin-molded, the safety factor is about 10 times that when the end of the insulating rod is crimped with a crimping fitting, and is sufficient for a bending load of F2 = 1000 (N). Has good mechanical strength.

  As described above, according to the lightning arrester according to the embodiment of the present invention, the insulating rod is passed through the plurality of insulating rod mounting holes that are drilled through the lower terminal electrode and the upper terminal electrode in the axial direction, thereby Since the casting resin is injected between the rod mounting hole and the insulating rod to fix the lower terminal electrode and the upper terminal electrode and the insulating rod, fastener parts such as bolts and screws are unnecessary, Drilling processing such as providing a stopper mounting hole in the insulating rod and machining such as screw processing are not required, so it is excellent in mechanical strength, improves assembly workability, and realizes cost reduction. it can.

  Further, since the O-ring 5 whose inner diameter is slightly smaller than the diameter of the insulating rod is disposed in the locking groove formed in the circumferential direction of the insulating rod mounting hole, when the casting resin is injected, It is possible to prevent the casting resin from leaking from the gap between the insulating rod mounting hole and the insulating rod.

  In the above description, a zinc oxide element is used as an example of a voltage nonlinear resistor, but the present invention is not limited by the type of voltage nonlinear resistor. Further, the present invention is not limited by the kind of the insulator covering material, the material of the casting resin, and the material of the insulating rod, which are the materials of the insulator. Although the number of insulating rods is four, it goes without saying that the configuration shown in the embodiment of the present invention can be applied to three or five or more insulating rods. Furthermore, although the pressing spring is illustrated as a coil spring, it is needless to say that the configuration shown in the embodiment of the present invention can be applied even if another spring such as a disc spring is used.

  The configurations described in the above embodiments are examples of the configurations of the present invention, and can be combined with other known techniques, and a part of the configurations is omitted without departing from the gist of the present invention. Needless to say, it is possible to change the configuration.

  As described above, the lightning arrester according to the present invention is useful as an invention that is excellent in mechanical strength, improves assembly workability, and realizes cost reduction.

DESCRIPTION OF SYMBOLS 1 Zinc oxide element 1a Zinc oxide element block 1b Serial body 1c Internal element 2 Press spring 3a Lower terminal electrode 3b Upper terminal electrode 32 Insulating rod mounting hole 33 Locking groove 34 Resin injection hole 4 Insulating rod 5 O-ring 6 Casting resin 7 Silicone rubber 8 Assembly jig 8a Lower plate 8b Upper plate 8c Support bar 8d Auxiliary plate 9 Jack

Claims (3)

A series body including a voltage non-linear resistor block in which a plurality of voltage non-linear resistors are stacked in the axial direction, and a pressing spring disposed at one end of the voltage non-linear resistor block;
A pair of terminal electrodes sandwiching the series body in the axial direction;
A plurality of insulating rods arranged along the axial direction around the series body and fixing the pair of terminal electrodes in a state in which a predetermined axial load is biased;
An insulating covering for covering and integrating an inner element including the series body and the insulating rod; and
With
The pair of terminal electrodes has a plurality of insulating rod mounting holes into which end portions of the insulating rods are inserted, and each insulating rod has both end portions penetrated through the insulating rod mounting holes, and the pair of terminal electrodes A lightning arrester characterized in that each of the insulating rods is resin-molded and fixed.   2. The lightning arrester according to claim 1, wherein the pair of terminal electrodes includes a locking groove formed in a circumferential direction of the insulating rod mounting hole, and an O-ring is disposed in the locking groove. A manufacturing method for assembling a lightning arrester including at least a lower terminal electrode, an upper terminal electrode, and an internal element using an assembly jig,
The internal element includes a voltage nonlinear resistor, a pressing spring, and a plurality of insulating rods,
The assembly jig includes an upper plate and a lower plate arranged opposite to each other, and a jack that biases a predetermined axial load on the lightning arrester. One end of each insulating rod is inserted into each insulating rod mounting hole of the lower terminal electrode. Inserting and fixing by resin molding;
Installing the lower terminal electrode on the lower plate of the assembly jig with the other end of each insulating rod facing upward;
Installing a voltage non-linear resistor block in which the voltage non-linear resistor is laminated between the insulating rods on the lower terminal electrode; and
Installing the pressing spring on top of the voltage nonlinear resistor block;
Disposing the upper terminal electrode so that the other end of each insulating rod is inserted into each insulating rod mounting hole of the upper terminal electrode;
Inserting the jack between the upper plate of the assembly jig and the upper terminal electrode;
Urging the predetermined axial load to the series body including the voltage non-linear resistor block and the pressing spring through the lower terminal electrode and the upper terminal electrode by the jack;
A step of resin-molding and fixing the upper terminal electrode and the other end of each insulating rod;
A method of manufacturing a lightning arrester, comprising:

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