JP2015070667A - Closed type switchgear - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain excellent non-linear resistance characteristics by providing a non-linear resistance film on an insulator supporting a high-voltage circuit instead of a lightning arrester and prescribing a film thickness dimension of this non-linear resistance film, and thereby, to restrict a high-frequency overvoltage while achieving reduction in insulation dimension and reduction in cost.SOLUTION: A non-linear resistance film 14 is applied on a surface of an insulator 19 continuously to a high-voltage conductor and a grounded sealed container. A film thickness dimension of the non-linear resistance film 14 is within 1.5 times a maximum particle diameter of MOV powder 15 of particles formed of a non-linear resistance material. Therefore, the MOV powder 15 is less likely to be joined in the thickness direction of the non-linear resistance film 14, and a shortest length of the conductive path is almost the same as a creepage length of the non-linear resistance film 14. Accordingly, the shortest length of the conductive path can be decided on the basis of the creepage length of the non-linear resistance film 14, and an operation voltage value and a withstanding voltage value of the non-linear resistance film 14 can be easily adjusted.

Description

  FIELD Embodiments described herein relate generally to a hermetic switchgear that suppresses high-frequency overvoltage.

  In recent years, power equipment for substation facilities is becoming more compact. For this reason, the insulation dimensions of power devices tend to be reduced, and there is a demand for further improving the reliability of power devices. In particular, a hermetic switchgear that is one of important power devices is required to improve reliability against steep wave overvoltage. The hermetic switchgear is a power device in which a high-voltage conductor supported by an insulator is disposed inside a hermetic container and an insulating gas is sealed inside the hermetic container.

  In order to improve the reliability against the steep wave overvoltage, it is important to limit the lightning overvoltage and the high frequency overvoltage that are the steep wave overvoltage. Specifically, lightning arresters are installed at substations for the purpose of protecting power equipment from lightning overvoltage. The installation position of the lightning arrester in the substation will be described with reference to FIG.

  As shown in FIG. 10, when a lightning overvoltage 2 occurs in the transmission line 1 due to a lightning strike or the like, the lightning overvoltage 2 enters the bus 4 of the substation via the bushing 3. The frequency of lightning overvoltage 2 is in the region of several hundred kHz, and the wavelength of lightning overvoltage 2 is larger than the dimensions of the substation. Therefore, the lightning arrester 6 is usually installed near the entrance of a substation connected to the power transmission line 1 or the transformer 5 which is an important device.

  With the lightning arrester 6 installed in such a position, the magnitude of the overvoltage of the entire substation can be limited to the lightning arrester protection level 7 which is LIWV or less. Further, since the lightning arrester 6 is only installed near the entrance of the substation or near the transformer 5, the number of installation is small, which is advantageous in terms of cost.

  On the other hand, when a closed switchgear operates inside a substation, a high frequency overvoltage that is a steep wave overvoltage is generated. As shown in FIG. 11, when the hermetic switch 8 operates to generate a discharge 10, a high frequency overvoltage is generated in the high voltage circuit 9. The high frequency overvoltage has only the circuit capacitance 11 in the high voltage circuit 9 (on both sides of the switchgear 8). Therefore, the energy of the high frequency overvoltage is significantly smaller than that of the lightning overvoltage 2.

  Further, the frequency of the high frequency overvoltage has a basic frequency determined by the capacitance 11 and the inductance 12 of the high voltage circuit 9, and there is a possibility that a high frequency overvoltage such as an area of several MHz to several tens of MHz is generated. There is. Since the frequency of such a high frequency overvoltage is higher by one digit or more than the frequency of the lightning overvoltage 2, the wavelength of the high frequency overvoltage is shorter than the dimensions of the substation. Therefore, the voltage level of the high frequency overvoltage varies greatly depending on the location of the substation. For example, as shown in FIG. 12, a high-frequency overvoltage 13 having a considerably higher level than the protection level 7 of the lightning arrester may be generated at the end of the high voltage circuit far from the place where the lightning arrester 6 is installed.

  Therefore, when designing a substation, it is necessary to analyze and examine the voltage level of the high frequency overvoltage in advance and reflect it in the insulation design, and a lightning arrester 6 is additionally installed at a position where the high frequency overvoltage 13 can be limited. However, it cannot be denied that the addition of the lightning arrester 6 causes an increase in cost. Therefore, in the future, there is a concern that the generation of the high-frequency overvoltage 13 may be a limiting condition for the reduction of the power equipment while further reducing the additional cost of the lightning arrester 6.

  In light of this situation, there is an urgent need to develop a technology that can suppress high-frequency overvoltage while avoiding the addition of lightning arresters. As a technique for controlling the electric field distribution without using a lightning arrester, a power device including a nonlinear resistance film has been proposed. For example, in Patent Document 1, a non-linear resistance film is provided on an insulating rod of a high-voltage device, and in Non-Patent Document 1, a non-linear resistance film is provided on the inner surface of a bushing insulator.

JP 2010-225532 A

IEEE Electrical Insulation Magazine p.p.18-29

  By the way, the above conventional example is a technique for suppressing a voltage having a relatively low frequency such as an AC voltage or a lightning voltage by a non-linear resistance film, and does not correspond to the limitation of the high frequency overvoltage. Therefore, it is expected to limit the high frequency overvoltage by providing a non-linear resistance film that does not deteriorate with the energy of the high frequency overvoltage. In particular, it is desired to suppress high-frequency overvoltage by applying a non-linear resistance film to the surface of an insulator that supports a high-voltage conductor.

  However, the following problems have been pointed out to meet the above needs. In general, the operating voltage value of a non-linear resistance material is almost determined for each non-linear resistance material, but the operating voltage value is a value per unit length, and the non-linear resistance of the entire non-linear resistance film using the non-linear resistance material. It was difficult to control the characteristics.

  Before describing the above problems in detail, first, the configuration of the nonlinear resistance film will be described with reference to FIGS. As shown in FIG. 13, the non-linear resistance film 14 is made of particles of non-linear resistance material made of zinc oxide or the like and having non-linear resistance characteristics, for example, MOV powder 15 which is a powder of a metal oxide varistor (hereinafter referred to as MOV). Is made of a composite material filled with a resin 16 such as epoxy.

  Inside the nonlinear resistance film 14, the MOV powder 15 is connected to form a nonlinear resistance conductive path (hereinafter simply referred to as a conductive path; indicated by a dotted line) 17. By the conductive path 17, the nonlinear resistance film 14 exhibits nonlinear resistance characteristics as shown in FIG. That is, the resistance value of the nonlinear resistance film 14 decreases nonlinearly when the applied voltage exceeds the operating voltage Vth.

  At this time, the operating voltage value and the withstand voltage value, which are the nonlinear characteristics of the entire nonlinear resistive film 14, are easily governed by the shortest length of the conductive path 17. In addition, the energy that can be processed by the entire nonlinear resistive film 14 is influenced by the number of current paths that can flow, and thus is easily governed by the number of conductive paths 17. Therefore, in order to grasp the nonlinear resistance characteristic of the nonlinear resistance film 14, it is important to evaluate the shortest length and number of the conductive paths 17.

  The volume% of the MOV powder 15 mixed in the non-linear resistance film 14 is determined by the amount of the MOV powder 15 contained in the non-linear resistance film 14. The probability of whether the unit volume is MOV can be determined. When evaluating the shortest length of the conductive path 17, there are the following methods.

  First, an arbitrary point in the nonlinear resistance film 14 is set as a start point, and it is confirmed whether or not the MOV powder 15 exists at the start point. When the presence of the MOV powder 15 is confirmed at the start point, the size of the MOV powder 15 to be evaluated is determined according to the probability determined by the particle size distribution. And the magnitude | size of the MOV powder 15 is examined sequentially regarding the point adjacent to a start point.

  In this case, if the location and the particle size of the MOV powder 15 from the start point to an arbitrary intermediate point are determined, the amount of the MOV powder 15 in the remaining region of the non-linear resistance film 14 is determined, and the point adjacent to the intermediate point. The probability that the MOV powder 15 is present on the surface is also determined. As described above, the existence of the MOV powder 15 is examined, and the length of connection of the MOV powder 15 from the start point to the final point, that is, the shortest length of the conductive path 17 is evaluated.

  By the way, as shown in FIG. 15, the MOV powder 15 is three-dimensionally and irregularly present in the nonlinear resistance film 14, and the MOV powder 15 is often connected three-dimensionally. If the connection between the MOV powders 15 is three-dimensional, the conductive path 17 formed by the connection of the MOV powders 15 is also formed three-dimensionally. For this reason, the shortest length and number of the conductive paths 17 cannot be determined from the surface area or volume of the nonlinear resistance film 14. As a result, it is difficult to adjust the operating voltage value and the withstand voltage value of the entire nonlinear resistive film 14, and it is difficult to grasp the nonlinear characteristics of the nonlinear resistive film 14.

  Moreover, if many MOV powders 15 are continuously present in the direction perpendicular to the creeping surface of the non-linear resistance film 14, the amount of the remaining MOV powder 15 is reduced without contributing to the progress of the conductive path 17 in the creeping direction. . As a result, the presence probability of the MOV powder 15 in the remaining volume region in the non-linear resistance film 14 is reduced, and the formation probability of the continuous conductive path 17 is lowered.

  An embodiment of the present invention has been proposed to solve the above-described problem. The object of the present invention is to provide a non-linear resistance film on an insulator that supports a high-voltage circuit instead of a lightning arrester. Providing a sealed switchgear that can limit the high-frequency overvoltage while reducing the insulation size and reducing the cost while providing excellent nonlinear resistance characteristics by regulating the film thickness dimension There is to do.

In order to achieve the above object, an embodiment of the present invention provides a sealed switchgear in which a high-voltage conductor supported by an insulator is sealed inside a grounded sealed container, and includes the following components (a) to ( c).
(A) A non-linear resistance film continuous to the high-voltage conductor and the grounded sealed container is provided on the surface of the insulator.
(B) The nonlinear resistance film is made of a composite material in which particles of a nonlinear resistance material having nonlinear resistance characteristics are filled in a resin.
(C) The film thickness dimension of the nonlinear resistance film is within 1.5 times the maximum particle diameter of the particles of the nonlinear resistance material.

(A) is a principal part front view of 1st Embodiment, (b) is a side view of 1st Embodiment. Sectional drawing of the nonlinear resistive film which concerns on 1st Embodiment. (A) is a principal part front view of 2nd Embodiment, (b) is a side view of 2nd Embodiment. The principal part sectional view of a 2nd embodiment. The graph which shows the operating voltage of the nonlinear resistive film in 3rd Embodiment. The graph which shows the operating voltage of the nonlinear resistive film in 3rd Embodiment. (A) is a principal part front view of 4th Embodiment, (b) is a side view of 4th Embodiment. (A) is a principal part front view of 5th Embodiment, (b) is a side view of 5th Embodiment. The graph which shows the operating voltage of the nonlinear resistive film in 6th Embodiment. The block diagram which shows the installation position of the conventional lightning arrester. The block diagram which shows generation | occurrence | production of the high frequency overvoltage when a sealing type switchgear operates. The block diagram for demonstrating the effect of the lightning arrester with respect to a high frequency overvoltage. Sectional drawing of the conventional nonlinear resistive film. The graph which shows a nonlinear resistance characteristic. Sectional drawing of the conventional nonlinear resistive film.

  DESCRIPTION OF EMBODIMENTS Hereinafter, a hermetic switchgear according to an embodiment of the present invention will be described with reference to the drawings. Each of the following embodiments is a hermetic switchgear in which a high-voltage conductor supported by an insulator is sealed inside a grounded hermetic container. The configuration of the nonlinear resistance film is basically the same as that of the nonlinear resistance film shown in FIG.

(1) First Embodiment [Configuration]
A first embodiment of the present invention will be described with reference to FIG. In FIG. 1, (a) is a front view of the main part of the first embodiment, and (b) is a side view of the first embodiment. As shown in FIG. 1, the hermetic switchgear according to the first embodiment is provided with a grounded hermetic container 18 in which an insulating gas is sealed.

  A high voltage conductor 20 extending in the axial direction of the grounded sealed container 18 is disposed inside the grounded sealed container 18. A disk-shaped insulator 19 is attached to the high voltage conductor 20, and the high voltage conductor 20 is supported by the grounded sealed container 18 by the insulator 19. The insulator 19 is provided with an opening at the center of the disk shape, and the high voltage conductor 20 is inserted into the opening. Further, the outer edge portion of the insulator 19 is fixed to the inner wall of the grounded sealed container 18.

  On the surface of the insulator 19, the non-linear resistance film 14 is continuously applied to the high voltage conductor 20 and the grounded sealed container 18. As shown in FIG. 2, the non-linear resistance film 14 has a film thickness dimension (left-right direction in FIG. 2) of 1. mm which is the maximum particle diameter of the MOV powder 15 which is particles of non-linear resistance material filled in the non-linear resistance film 14. It is configured to be within 5 times.

[Action and effect]
In the first embodiment having the above configuration, since the operating voltage is always applied to the nonlinear resistance film 14, the nonlinear resistance film 14 must ensure withstand voltage reliability with respect to the operating voltage. Therefore, the operating voltage value of the non-linear resistance characteristic in the non-linear resistance film 14 needs to be adjusted to a level that limits the high-frequency overvoltage value by reducing the AC leakage current and lowering the resistance when the high-frequency overvoltage is applied.

  In the conventional case shown in FIG. 15, the film thickness dimension of the non-linear resistance film 14 is sufficiently thicker than the diameter of the MOV powder 15, and the conductive path 17 is formed three-dimensionally. Thus, it is difficult to obtain the shortest length of the conductive path 17 from the shape of the nonlinear resistance film 14.

  In particular, since the conductive path 17 is three-dimensionally formed in the nonlinear resistance film 14, the MOV powder 15 is not continuously in the creeping direction of the nonlinear resistance film 14 but continuously in the thickness direction perpendicular to the creeping surface. It tends to exist. Therefore, the conductive path 17 hardly progresses in the creeping direction, and the amount of the remaining MOV powder 15 is reduced in such a situation. As a result, the existence probability of the MOV powder 15 in the remaining volume region in the nonlinear resistance film 14 is reduced, and the formation probability of the continuous conductive path 17 is reduced.

  On the other hand, in the first embodiment, the film thickness dimension of the non-linear resistance film 14 is made thinner than 1.5 times the diameter of the MOV powder 15, so that the MOV powder 15 is as shown in FIG. Therefore, it is difficult to connect the nonlinear resistance film 14 in the thickness direction. For this reason, the conductive path 17 is formed two-dimensionally, not three-dimensionally.

  That is, in this embodiment, the film thickness dimension of the non-linear resistance film 14 is within 1.5 times the maximum particle size of the MOV powder 15, so that the MOV powder 15 having a size near the maximum particle size is Even if the MOV powder 15 is shifted and connected in the thickness direction perpendicular to the creeping surface of the nonlinear resistance film 14, the center of the MOV powder 15 is shifted in the creeping direction, which contributes to the progress of the conductive path 17 in the creeping direction. The probability of forming the conductive path 17 increased. Moreover, in the present embodiment, when determining the film thickness dimension of the nonlinear resistance film 14, the maximum particle size of the MOV powder 15 is used as a reference, so that the volume of the MOV powder 15 is large and the formation probability of the conductive path 17 is improved. The impact can be increased.

  In such a nonlinear resistance film 14, the shortest length of the conductive path 17 can be made substantially equal to the creeping length of the nonlinear resistance film 14. As a result, the shortest length of the conductive path 17 can be easily determined based on the creeping length of the non-linear resistance film 14, and the operating voltage value and resistance to resistance of the non-linear resistance film 14 affected by the shortest length of the conductive path 17 can be determined. The voltage value can be easily adjusted.

  According to the nonlinear resistance film 14, the resistance value with respect to the operating voltage is kept high to reliably reduce the AC leakage current, and at the same time, when the high frequency overvoltage is applied, the resistance becomes low and the high frequency overvoltage 13 can be reliably suppressed. Thereby, the insulation reliability of the insulator 19 provided with the nonlinear resistance film 14 is greatly improved.

  In the first embodiment as described above, the insulation reliability of the entire substation is ensured by arranging a plurality of insulators 19 provided with the non-linear resistance film 14 inside the hermetic switchgear instead of the lightning arrester 16. can do. Moreover, it is possible to reduce the cost by avoiding the addition of the lightning arrester 16, and it is possible to contribute to further downsizing of the hermetic switchgear while suppressing the additional cost of the lightning arrester.

(2) Second Embodiment [Configuration]
The second embodiment will be described with reference to FIGS. In the second embodiment, four grooves 21 are formed in a spiral shape on the surface of the insulator 19 with a predetermined curve in the radial direction. The groove 21 has a rectangular cross section (see FIG. 4). In the second embodiment, the nonlinear resistance film 14 is applied so as to fill the groove 21. The groove portion 21 is formed from the end portion on the center side of the insulator 19 in contact with the high voltage conductor 20 to the end portion on the outer edge side of the insulator 19 in contact with the grounded sealed container 18. Therefore, the non-linear resistance film 14 is continuously provided on the high voltage conductor 20 and the grounded sealed container 18.

  The depth dimension of the groove portion 21 is configured to be within 1.5 times the maximum particle diameter of the MOV powder 15. The width dimension of the groove part 21 should just be more than the largest particle diameter of the MOV powder 15, and if it is the width | variety which can apply | coat the nonlinear resistance film 14 uniformly, you may change suitably according to the viscosity of the nonlinear resistance material to apply | coat. The number of grooves 21 is not limited to four, and can be arbitrarily selected according to the surge energy processed by the nonlinear resistance film 14.

[Action and effect]
In the second embodiment as described above, the non-linear resistance film 14 is continuously applied to the high voltage conductor 20 and the grounded sealed container 18. Since the non-linear resistance film 14 is applied to the groove portion 21 having a depth within 1.5 times the maximum particle diameter of the MOV powder 15, the film thickness dimension of the non-linear resistance film 14 is 1. Within 5 times. The length dimension of the groove 21 can be adjusted according to the non-linear characteristic of the non-linear resistance material so that the entire non-linear resistance film 14 has the desired non-linear resistance characteristic.

  In the second embodiment, since the depth of the groove 21 is within 1.5 times the maximum particle diameter of the MOV powder 15, the non-linear resistance film 14 is simply applied by coating the non-linear resistance film 14 so as not to overflow the groove 21. The film thickness can be kept within 1.5 times the maximum particle size of the MOV powder 15.

  Therefore, the non-linear resistance film 14 having a desired film thickness can be formed by a simple coating operation, and the MOV powder 15 is difficult to be connected in the thickness direction of the non-linear resistance film 14, so that the non-linear resistance The operating voltage of the nonlinear resistance characteristic of the film 14 can be easily adjusted by the length of the groove 21. Therefore, the resistance value with respect to the operating voltage is high, the AC leakage current can be reliably reduced, and the non-linear resistance characteristic can be reliably operated with respect to the high frequency overvoltage.

  In addition, the insulator 19 having a certain degree of hardness is cut to provide a groove portion 21 having a desired depth. Such a cutting operation is compared with an operation for adjusting the film thickness dimension of the viscous nonlinear resistance film 14. The workability is good, and the depth of the groove 21 can be adjusted with high accuracy. Therefore, the film thickness dimension of the nonlinear resistance film 14 can be adjusted with high accuracy, and the nonlinear resistance characteristic can be controlled at a high level.

  Furthermore, since the groove 21 has a spiral shape, the length of the nonlinear resistive film 14 from the high voltage conductor 20 to the grounded sealed container 18 can be changed with a high degree of freedom. It is easy to adjust the operating electric field as a whole. As a result, the insulation reliability of the insulator 19 provided with the nonlinear resistance film 14 is improved, and the insulation reliability of the entire substation can be ensured by arranging a plurality of insulators 19 provided with the nonlinear resistance film 14. .

(3) Third Embodiment [Configuration]
A third embodiment will be described with reference to the graphs of FIGS. The third embodiment is a sealed switchgear in which a high-voltage conductor 20 supported by an insulator 19 is sealed inside a grounded sealed container 18, and a non-linear resistance film 14 is sealed on the surface of the insulator 19. 18 is applied continuously. The feature of the third embodiment is that the operating voltage of the non-linear resistance film 14 is 1.2 times or more of LIWV (Lightning Impulse Withstand Voltage, lightning impulse withstand voltage value).

[Action and effect]
As described above, the lightning overvoltage 2 entering the substation from the transmission line 1 is effectively limited to LIWV or less by the lightning arrester 6 installed near the substation entrance or the transformer 5. On the other hand, the high-frequency overvoltage generated when the closed switchgear 8 in the substation operates may possibly exceed the LIWV depending on the location.

  Insulation performance against high-frequency overvoltage in high-voltage equipment is often equal to or better than insulation performance against lightning overvoltage. If the operating electric field of the non-linear resistance film 14 applied to the insulator 19 is set to LIWV or less, the non-linear resistance film 14 may operate due to lightning overvoltage, and lightning current may flow. The energy of lightning overvoltage is very large, and there is a high possibility that the nonlinear resistance film 14 is thermally damaged. Therefore, if the operating voltage of the non-linear resistance film 14 is set to about 1.2 times LIWV, the non-linear resistance film 14 will not operate at lightning overvoltage 2, and the non-linear resistance film 14 may be damaged by excessive energy. Disappear.

  In addition, since the insulation performance against high frequency overvoltage of high-voltage equipment is often about 1.2 times or more that of lightning overvoltage 2, the operating voltage of the non-linear resistance film 14 is made about 1.2 times LIWV. This can also prevent the influence on the insulation performance of high-voltage equipment. As described above, in the third embodiment, the insulation reliability of the insulator 19 and the entire substation is improved by providing the non-linear resistance film 14 having the operating voltage 1.2 times or more of LIWV. .

(4) Fourth Embodiment [Configuration]
A fourth embodiment will be described with reference to FIG. The fourth embodiment is a hermetic switchgear in which a high-voltage conductor 20 supported by an insulator 19 is sealed inside a grounded hermetic container 18, and is insulated between the non-linear resistance film 14 and the high-voltage conductor 20. It is characterized in that the distance 22 is secured. That is, in the fourth embodiment, the non-linear resistance film 14 that is continuous with the sealed ground container 18 is applied to the surface of the insulator 19.

[Action and effect]
In the fourth embodiment, the nonlinear resistance film 14 and the high voltage conductor 20 are insulated. For this reason, there is no current path directly passing through the non-linear resistance film 14 between the high voltage conductor 20 and the sealed ground container 18. Therefore, a minute AC leakage current does not flow from the high-voltage conductor 20 to the sealed grounded container 18 through the non-linear resistance film 14 in a state where a normal AC operating voltage is applied. By eliminating the leakage current, the non-linear resistance film 14 is not deteriorated, and long-term reliability in the operating state can be improved.

  Further, the lightning overvoltage 2 having a large energy is in a region where the frequency is about several hundred kHz, and is one digit or more lower than the high frequency overvoltage 13 generated when the hermetic switch 8 is operated. Therefore, when the lightning overvoltage 2 occurs, the impedance of the capacitance 23 between the non-linear resistance film 14 and the high-voltage conductor 20 becomes high, and no current flows through the non-linear resistance film 14. There is no possibility that the non-linear resistance film 14 is damaged.

  On the other hand, for the high frequency overvoltage 13, the impedance of the capacitance 23 between the nonlinear resistance film 14 and the high voltage conductor 20 becomes low, and a current flows through the nonlinear resistance film 14, so Can act reliably. As described above, according to the fourth embodiment, the insulation reliability of the insulator 19 provided with the non-linear resistance film 14 can be kept high, and the high frequency generated when the hermetic switch 8 is operated. An overvoltage can be suppressed, and a compact closed type switchgear with high withstand voltage reliability can be supplied.

(5) Fifth Embodiment [Configuration]
The fifth embodiment will be described with reference to FIG. The fifth embodiment is a hermetic switchgear in which a high-voltage conductor 20 supported by an insulator 19 is hermetically sealed inside a grounded hermetic container 18, and between the nonlinear resistance film 14 and the high-voltage conductor 20. The insulation distance 22 is secured, and the non-linear resistance film 14 is continuously applied only to the grounded sealed container 18 in the groove portion 21 provided on the surface of the insulator 19.

[Action and effect]
In the fifth embodiment, since the insulation distance 22 is ensured between the nonlinear resistance film 14 and the high voltage conductor 20, the nonlinear resistance film 14 and the high voltage conductor 20 are insulated. For this reason, there is no current path directly passing through the non-linear resistance film 14 between the high-voltage conductor 20 and the grounded sealed container 18.

  Therefore, a minute AC leakage current does not flow from the high-voltage conductor to the ground container through the non-linear resistance film 14 in a state where a normal AC operating voltage is applied. This eliminates the deterioration of the nonlinear resistance film 14 and improves long-term reliability in the operating state. Further, since the nonlinear resistance film 14 is applied to the groove portion 21 provided in the insulator 19, the operation of the entire nonlinear resistance film 14 is adjusted by adjusting the length of the groove portion 21 according to the nonlinear characteristic of the powder 15 of the nonlinear resistance material. The voltage can be adjusted.

  In the fifth embodiment, it is easy to adjust the non-linear resistance characteristic by the length dimension of the non-linear resistance film 14. In addition, since the shape of the groove 21 is spiral, it is easy to adjust the length of the nonlinear resistive film 14 from the high voltage conductor 20 to the grounded sealed container 18. As a result, the operating voltage of the non-linear resistance film 14 can be easily controlled, and effective overvoltage limitation can be easily performed by the insulator 19 provided with the non-linear resistance film 14.

(6) Sixth Embodiment [Configuration]
The sixth embodiment will be described with reference to the graph of FIG. In the sixth embodiment, in a hermetic switchgear in which a high voltage conductor 20 supported by an insulator 19 is hermetically sealed in a grounded hermetic container 18, the nonlinear resistance film 14 is hermetically grounded on the surface of the insulator 19. The container 18 is continuously applied. In the sixth embodiment, the nonlinear resistive film 14 and the high voltage conductor 20 are insulated. Furthermore, the sixth embodiment is characterized in that the operation voltage of the nonlinear resistance film 14 is configured to be LIWV or less.

[Action and effect]
The lightning overvoltage 2 that enters the substation via the transmission line 1 is effectively limited to LIWV or less by the lightning arrester 6 installed near the entrance of the substation or the transformer 5. On the other hand, the high frequency overvoltage generated when the hermetic switch 8 in the substation is opened or closed may exceed the LIWV depending on the location in the substation.

  When the non-linear resistance film 14 is applied continuously to the surface of the insulator 19 with the high-voltage conductor 20 and the grounded sealed container 18, the operating electric field of the non-linear resistance film 14 is reduced to LIWV or less, so that the high-frequency overvoltage can be more effectively reduced. There is a possibility that it can be suppressed. However, when the non-linear resistance film 14 is operated at the lightning overvoltage 2 and the lightning overvoltage 2 flows through the non-linear resistance film 14, since the energy of the lightning overvoltage 2 is generally large, there is a high possibility that the non-linear resistance film 14 is damaged.

  On the other hand, in the sixth embodiment, the non-linear resistance film 14 and the high-voltage conductor 20 are insulated and coupled with an appropriate capacitance 23. For this reason, even if the operating voltage of the non-linear resistance film 14 is LIWV or less, the impedance of the capacitance 23 is large for a lightning overvoltage having a relatively low frequency, so that a large current does not flow through the non-linear resistance film 14. .

  For the high frequency overvoltage 13 whose frequency is one digit or more larger than the lightning overvoltage 2, the impedance of the capacitance 23 is lowered and the non-linear resistance film 14 operates to suppress the overvoltage. In general, since the energy of the high frequency overvoltage 13 is small, the nonlinear resistance film 14 is not damaged. As a result, the insulation reliability of the insulator 19 provided with the nonlinear resistance film 14 is improved. Therefore, by arranging a plurality of insulators 19 having the non-linear resistance film 14, high frequency overvoltage can be suppressed, and insulation reliability of the entire substation can be ensured.

(7) Other Embodiments The above embodiment is presented as an example in the present specification, and is not intended to limit the scope of the invention, and may be implemented in various other forms. Is possible. Various omissions, replacements, and changes may be made without departing from the scope of the invention. These embodiments and modifications thereof are included in the invention described in the claims and equivalents thereof in the same manner as included in the scope and gist of the invention.

DESCRIPTION OF SYMBOLS 1 ... Power transmission line 2 ... Lightning overvoltage 3 ... Bushing 4 ... Bus 5 ... Transformer 6 ... Lightning arrester 7 ... Lightning arrester protection level 8 ... Sealing type switchgear 9 ... High voltage circuit 10 ... Discharge 11 ... Circuit capacitance 12 ... Inductance 13 ... High-frequency overvoltage 14 ... Nonlinear resistance film 15 ... MOV powder 16 ... Resin 17 ... Conductive path 18 ... Grounded sealed container 19 ... Insulator 20 ... High-voltage conductor 21 ... Groove 22 ... Insulation distance 23 ... Capacitance

Claims (6)

In a closed type switchgear in which a high voltage conductor supported by an insulator is sealed inside a grounded sealed container,
On the surface of the insulator, a non-linear resistance film is continuously applied to the high-voltage conductor and the grounded sealed container,
The nonlinear resistance film is made of a composite material in which particles of a nonlinear resistance material having nonlinear resistance characteristics are filled in a resin,
A hermetic switchgear characterized in that the film thickness dimension of the nonlinear resistance film is within 1.5 times the maximum particle diameter of the particles of the nonlinear resistance material. Forming a groove for applying the nonlinear resistance film on the surface of the insulator;
2. The hermetic switch according to claim 1, wherein a depth dimension of the groove is set to be within 1.5 times a maximum particle diameter of the particles of the nonlinear resistance material. On the surface of the insulator, a non-linear resistance film is provided continuously to the grounded sealed container,
3. The hermetic switchgear according to claim 1, wherein an insulation distance is provided between the nonlinear resistance film and the high voltage conductor.   4. The hermetic switchgear according to claim 3, wherein a groove for applying the nonlinear resistance film is formed on the surface of the insulator.   5. The hermetic switch according to claim 3, wherein an operating voltage of the non-linear resistance film is LIWV or less. In a closed type switchgear in which a high voltage conductor supported by an insulator is sealed inside a grounded sealed container,
On the surface of the insulator, a non-linear resistance film is continuously applied to the high-voltage conductor and the grounded sealed container,
The hermetic switchgear characterized in that the operating voltage of the non-linear resistance film is 1.2 times or more of LIWV.

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