JP2005033930A - Stress cone for termination joint - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To achieve weight reduction and cost reduction while preserving constant field effect relaxation effect, and besides to set it up in a short time. <P>SOLUTION: A stress cone for a termination joint (reinforcing stress cone ) 130 is composed of a bell mouth part 131 which relaxes the field of a high field part arising at the termination 10 of a power cable, and a reinforcing compact 132 which relaxes the creeping field at the surface of the bell mouth part 131. The reinforcing compact 132 is made by axially arranging a plurality of dielectric constant layers 132a-132f each different in dielectric constant. Moreover, this stress cone 130 for a termination joint is made integrally or in parts. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a stress cone for terminal connection.

  In general, a power cable such as a CV (crosslinked polyethylene insulation) cable is provided with a shielding layer (external semiconductive layer) on the insulator in order to reduce electric field stress in the insulator. When forming the terminal connection portion of such a power cable, simply removing the shielding layer may concentrate electric field stress on the end portion of the shielding layer and cause dielectric breakdown. For this reason, various measures are taken so that electric field stress is not concentrated particularly at the terminal connection portion of the high-voltage power cable.

  As an example, a stress cone is conventionally used for a terminal connection portion of a power cable such as a CV cable.

  The stress cone has a shape in which a tip end is widened in a trumpet shape radially outward, and an electric field at the end of the shielding layer is brought into contact with the end of the shielding layer of the power cable. It is intended to relieve stress. However, with this stress cone alone, as the voltage increases, the layered electric field stress (insulator surface) on the surface of the stress cone increases, which may cause a surface flash of the stress cone.

  Therefore, a capacitor cone is conventionally used as one method for improving the surface flash characteristics of the stress cone at the terminal connection portion of the high-voltage power cable (see, for example, Patent Document 1). This capacitor cone is obtained by providing a thin metal foil electrode in oil-insulated insulating paper and appropriately distributing the capacitance between the foils.

  FIG. 4 is a cross-sectional view of an essential part showing an example of a structure of a terminal connection portion of a conventional power cable using a capacitor cone.

  The terminal connection portion 1 shown in FIG. 4 is provided with a soot tube 4 around the cable insulator 3 in the end portion 2 of the power cable, and a space 5 between the inner peripheral surface of the soot tube 4 and the outer peripheral surface of the cable insulator 3. Inside, a pre-mold insulator (stress cone) 7 and a capacitor cone 8 connected via an epoxy seat 6 having a substantially conical cylindrical shape opening downward are provided.

  The premold insulator (stress cone) 7 is pushed into the epoxy seat 6 from below by the elastic force of a spring of a pressing device (not shown) coupled to the lower metal fitting 9 and is provided on the cable insulator 3. .

  The capacitor cone 8 is constituted by a plurality of capacitor elements 8 a to 8 d surrounding the periphery of the cable insulator 3 via the insulating cylinder 10. The plurality of capacitor elements 8 a to 8 d are each formed by winding a plurality of oil-insulated insulating papers 11 having different diameter dimensions and axial dimensions from each other in a cylindrical shape, and between the wound oil-insulated insulating papers 11, from an aluminum foil or the like. A plurality of cylindrical electrodes 12 are arranged side by side in the axial direction so that their end portions are opposed to each other in the radial direction. Thereby, the electrodes 12 are arranged between the high voltage side and the ground side along the terminal end 2 of the power cable. At this time, the capacitor cone 8 is designed so that the capacitance between the electrodes 12 is appropriately distributed, and the voltage between the electrodes 12 is uniformly shared by the layered electric field stress on the surface of the premolded insulator 7. Yes.

The assembly of the capacitor cone 8 is performed by dividing the plurality of capacitor elements 8a to 8d with a slight difference in diameter so that the operator can easily assemble the capacitor elements 8a to 8d. It is performed by joining together. In addition, after the assembly of the capacitor cone 8 is completed, the cylindrical space 5 is filled with oil.
JP-A-8-306524

  However, in a terminal connection portion of a conventional power cable using a capacitor cone, each time a divided body of a plurality of capacitor elements 8a to 8d having a slight difference in diameter is inserted into the power cable and joined, each is joined. It is essential to wrap the oil-insulated insulating paper for the gap in order to fill the gap between the capacitor elements 8a to 8d. Since this work is complicated and requires skill, it takes time to assemble.

  Further, since the oil-impregnated insulating paper 11 is used, it is necessary to fill oil into the cylindrical space 5 in which the capacitor elements 8a to 8d are arranged after the assembly of the capacitor cone is completed. At the same time, it tends to lead to weight. Currently, it is not easy to train condenser corn producers.

  The present invention has been made in view of such a point, and it is possible to reduce the weight and cost while maintaining a certain electric field relaxation effect, and to easily assemble the stress for a terminal connection portion in a short time. The purpose is to provide corn.

  The stress cone for the terminal connection portion of the present invention has a stress cone body that relaxes the electric field of the high electric field portion generated at the end of the power cable, and a reinforcing molded body that relaxes the creeping electric field on the surface of the stress cone body, The said reinforcement molded object takes the structure currently formed so that a dielectric constant may differ in an axial direction. Preferably, the reinforcing molded body has a configuration in which the dielectric constant is decreased from the low pressure side toward the high pressure side.

  According to this configuration, the reinforcing molded body that relaxes the creeping electric field on the surface of the stress cone body is formed so that the dielectric constant differs in the axial direction, preferably the dielectric constant decreases from the low pressure side toward the high pressure side. Therefore, it is possible to appropriately distribute the creeping electric field generated on the surface of the stress cone main body to the reinforcing molded bodies having different dielectric constants. For example, the capacitor cone is used without using the capacitor cone. A constant electric field relaxation effect equivalent to the case can be maintained. In addition, the oil necessary for the capacitor cone becomes unnecessary. For example, when the material is rubber, an insulating gas can be used, and the weight can be reduced. Furthermore, since it can be integrally formed as will be described later, it is possible to reduce the cost and to assemble easily in a short time.

  The stress cone for terminal connection portions of the present invention adopts a configuration in which the above-described configuration is integrally formed or divided into a plurality of portions.

  According to this configuration, the stress cone main body and the reinforcing molded body are appropriately integrally formed entirely or partially, so that the number of parts is reduced, the cost is reduced, and the stress cone body and the reinforcing molded body are easily assembled in a short time. Can do.

  The stress cone for a terminal connection portion according to the present invention has the above-described configuration, wherein the reinforcing molded body is formed by arranging a plurality of dielectric layers having different dielectric constants in the axial direction, and the plurality of dielectric layers are respectively A structure that is formed using materials having different dielectric constants, or that is formed by changing the concentration of each dielectric material, or that is formed by mixing a plurality of materials with different mixing ratios. Take.

  According to this configuration, the reinforcing molded body is formed of a plurality of dielectric constant layers, and the plurality of dielectric constant layers are formed using materials having different dielectric constants, or the respective dielectric material concentrations are changed. Therefore, it is possible to form a reinforced molded body in which the dielectric constant changes stepwise in the axial direction.

  The stress cone for a terminal connection portion according to the present invention has the above-described configuration, wherein the reinforcing molded body is formed by continuously changing the concentration of the dielectric material, or by continuously changing the mixing ratio of a plurality of materials. The structure formed by mixing is taken.

  According to this configuration, the dielectric constant is continuous in the axial direction in order to form a reinforced molded body by continuously changing the concentration of the dielectric material or by changing the mixing ratio of a plurality of materials and mixing them. Can be formed.

  As described above, according to the present invention, weight reduction and cost reduction can be achieved while maintaining a certain electric field relaxation effect, and the assembly can be easily performed in a short time.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. Here, the term “terminal connection part” refers to a so-called air terminal connection part, that is, a general terminal part for connecting a power cable terminal part to, for example, a transformer, an overhead line, a substation bus, or the like. means.

  FIG. 1 is a partial vertical cross-sectional view showing a structure of a terminal connection part of a power cable using a stress cone for terminal connection part according to an embodiment of the present invention. FIG. 2 is an enlarged cross-sectional view of a main part of the terminal connection part of FIG. 1 including the stress cone for the terminal connection part according to the present embodiment.

  In FIG. 1, a power cable terminal connection unit 100 is used to connect the terminal unit 110 a of the power cable 110 to a transformer, an overhead line, a substation bus, or the like as described above.

  The power cable 110 is configured by covering the periphery of the cable conductor 111 with an internal semiconductive layer (not shown), a cable insulator 113, an external semiconductive layer 115, and a cable sheath 117 in order from the inside. In the end portion 110a of 110, the cable conductor 111, the cable insulator 113, and the external semiconductive layer 115 are exposed in a predetermined length in order from the end of the power cable 110, respectively. That is, the terminal portion 110a of the power cable 110 is configured by peeling off the cable insulator 113, the external semiconductive layer 115, and the cable sheath 117 that constitute the power cable 110 in order from the outside by a predetermined length. .

  Here, the cable insulator 113 is made of an insulating rubber plastic material, such as ethylene propylene rubber, polyethylene, or cross-linked polyethylene. The outer semiconductive layer 115 is made of a conductive material, for example, an elastomer such as ethylene propylene rubber, silicone rubber, or ethylene vinyl acetate mixed with a conductive substance such as carbon.

  In the terminal end portion 110 a of the power cable 110, the lower end portion of the conductor lead bar 121 disposed on the coaxial line with the power cable 110 is fixed to the end portion of the cable conductor 111 exposed at the terminal end of the power cable 110. The conductor lead bar 121 is inserted through the cover 123 above the cable conductor 111, and is connected to a transformer, an overhead wire, a substation bus, and the like at the upper end. The cover 123 is fixed to a soot tube 125 arranged so as to surround the cable insulator 113 and the cable conductor 111.

  The soot tube 125 is made of an insulating material (for example, made of ceramics, rubber plastic, etc.), and is formed by providing a fold portion so as to project radially in the outer peripheral surface of the conical tube-like soot tube body. . In the soot tube main body, the upper end opening is disposed above the tip of the cable conductor 111 (that is, the end of the power cable 110), and the lower end opening is disposed around the base end of the cable insulator 113.

  A cover 123 is fixed to the upper end opening of the soot tube main body of the soot tube 125 via an upper metal fitting 126, and the upper end opening of the soot tube body is hermetically sealed by the cover 123 and a conductor lead bar 121 inserted through the cover 123. It is in the state. Further, the lower end opening of the soot tube main body of the soot tube 125 is fixed in close contact with the ring-shaped auxiliary metal fitting 127 in which the end portion 110a of the power cable 110 is inserted at the center via an O-ring 128.

  A terminal connection stress cone 130 is attached to the upper surface of the auxiliary metal fitting 127 via a connecting member 129. The end connection stress cone 130 is provided on the cable insulator 113 in a sealed internal space 140 between the outer peripheral surface 113a of the cable insulator 113 and the inner peripheral surface of the vertical tube 125. .

  The end connection stress cone 130 is a central member of the present embodiment as an object of the present invention, and has both functions of a conventional stress cone and a capacitor cone as will be described later. is there. Hereinafter, in order to clarify the difference from the conventional stress cone, the end connection stress cone 130 will be referred to as a “reinforced stress cone”. The reinforcing stress cone 130 will be described in detail later.

  The connecting member 129 is inserted into the cable insulator 113 and has a cylindrical main body portion 129a whose tip is inserted into the lower end portion of the reinforced stress cone 130, and a flange portion 129b protruding outward from the lower end of the cylindrical main body portion 129a. And have. The outer diameter of the flange portion 129b is larger than the inner diameter of the auxiliary metal fitting 127, and the flange portion 129b is fixed to the inner peripheral portion of the upper surface of the auxiliary metal fitting 127.

  A support frame 142 into which the power cable 110 is inserted is coupled to the outer peripheral edge of the lower surface of the auxiliary metal fitting 127 via a bolt 143. The support frame 142 has a soot pipe 125 fixed to its upper surface via bolts 144. Further, the lower surface of the support frame 142 is attached to the installation base 146 via a support insulator 145, and the terminal connection portion of the cable is electrically insulated from the installation base 146.

  Further, the upper end of the lower fitting 148 disposed around the lower end portion of the cable insulator 113 is airtightly joined to the inner peripheral edge of the lower surface of the auxiliary fitting 127 by a bolt 151 and a packing 154. Is hermetically coupled to the end of the cable sheath 117 via a seal tape 156.

Further, an insulating gas (for example, generally sulfur hexafluoride (SF ₆ ) gas or the like) is sealed in the cylindrical internal space 140 in the soot pipe 125.

  Next, the reinforced stress cone 130 that is a central member of the present embodiment will be described in detail.

  As shown in FIGS. 1 and 2, the reinforced stress cone 130 is disposed in a state where the inner peripheral surface 136 is in close contact with the outer peripheral surface 113a of the cable insulator 113, and the outer peripheral surface 137 has an upper end from the lower end side. Inclined so as to approach the cable shaft side from the low voltage side to the high voltage side of the power cable 110.

  Further, the reinforced stress cone 130 is an elastic body, and here, the inner diameter of the reinforced stress cone 130 is formed to be smaller than the outer diameter of the cable insulator 113 in a natural state. As a result, the reinforced stress cone 130 comes into close contact with the outer peripheral surface 113a of the cable insulator 113 by the inner peripheral surface pressing the outer peripheral surface 113a of the cable insulator 113, and as a result, the end portion 110a of the power cable 110 Insulation is maintained.

  The reinforced stress cone 130 is formed on the surface of the bell mouth portion 131 between a high electric field portion generated in the terminal portion 110 a of the power cable 110 and a conductive bell mouth-like body (hereinafter referred to as “bell mouth portion”) 131 of the low electric field portion. And an insulation reinforcing molded body 132 that alleviates electric field stress in the direction of layering.

  In the present embodiment, the bell mouth portion 131 and the insulation reinforcing molded body 132 in the reinforced stress cone 130 are integrally formed, so that it is not necessary to handle both separately, and it is easy to handle and the workability is improved.

  The bell mouth portion 131 is made of an elastic material in which a conductive material such as carbon is mixed with ethylene propylene rubber, silicone rubber, or the like, and is formed in a trumpet shape in which a cylindrical body is extended toward the end of the power cable 110. That is, the inner peripheral surface of the lower portion 131a of the bell mouth portion 131 (hereinafter referred to as “bell mouth lower portion”) 131a is in contact with the outer peripheral surface 113a of the cable insulator 113 and the outer peripheral surface 115a of the outer semiconductive layer 115, respectively. The inner peripheral surface of the upper portion 131b (hereinafter referred to as “bell mouth upper portion”) 131b of the mouse portion 131 is formed so as to be separated from the outer peripheral surface 113a upward from the upper end of the bell mouth lower portion 131a. In addition, the upper end of the bell mouth upper portion 131b is rounded.

  The lower end surface 134 of the bellmouth lower portion 131a is formed with a cutout portion 134a into which the tip of the connecting member 129 is inserted, and the bellmouth upper portion 131b corresponds to the surface shape of the bellmouth upper portion 131b continuously in the axial direction. The lower end portion of the insulation reinforcing molded body 132 having the above-described shape, specifically, the lower end surface 135 of the dielectric constant layer 132a is joined in close contact.

  With the above configuration, the bell mouth portion 131 relaxes the high electric field portion generated at the end portion of the external semiconductive layer 115 of the power cable 110 by connecting the bell mouth lower portion 131a to the end portion of the external semi conductive layer 115. To do.

  The insulation-reinforcement molded body 132 is made of an elastic body mainly composed of ethylene polypropylene, silicone, or the like. The inner peripheral surface 136 is in close contact with the outer peripheral surface 113a of the cable insulator 113, and the outer peripheral surface 137 is the upper end portion from the lower end side. That is, it is formed in a substantially conical cylinder shape that is inclined so as to gradually approach the outer peripheral surface 113a of the cable insulator 113 from the low-voltage side to the high-voltage side in the terminal portion 110a of the power cable 110.

  The insulation-reinforcing molded body 132 includes a plurality of (here, six) dielectric constant layers 132a, 132b, 132c, 132d, 132e, and 132f having different dielectric constants arranged in the axial direction, and these dielectric constant layers 132a to 132f. Is formed integrally. In the present embodiment, the insulation reinforcing molded body 132 is disposed so that the dielectric constant gradually decreases toward the high voltage side at the terminal portion 110a of the power cable 110 to be attached.

  The dielectric constants of the plurality of dielectric constant layers 132a to 132f are different on the surface of the bellmouth portion 131, that is, on the surface of the bellmouth upper portion 131b including the rounded upper end of the bellmouth upper portion 131b. This is because electric field stress is suitably distributed to each of the dielectric constant layers 132a to 132f. In the present embodiment, the electric field stress is configured to be uniformly distributed.

  Further, the interface 138 between adjacent dielectric constant layers of the plurality of dielectric constant layers 132 a to 132 f is gradually separated from the outer peripheral surface 113 a of the cable insulator 113 from the lower end side to the upper end side of the reinforced stress cone 130. That is, it is inclined substantially linearly so as to rise outward.

  Due to this inclination, the electric field generated at the end of the power cable 110 is less likely to concentrate on the interface 138 between the dielectric layers 132a to 132f.

  The linear inclination angle at the interface 138 may be any inclination angle as long as it is suitable for electric field relaxation. For example, it may be a curved line in the shape of the soot tube.

  The interface 138 may have any inclination as long as it is inclined so as to rise from the lower end side to the upper end side of the reinforced stress cone 130. For example, the interface 138 may be a curved surface.

  In the present embodiment, the plurality of dielectric constant layers 132a to 132f are made of a material having a different dielectric constant (for example, a high dielectric constant material such as barium titanate or zinc oxide) as an additive to a main material such as ethylene polypropylene or silicone. And is integrally molded so that the dielectric constant decreases toward the upper end side which is the high voltage side.

  In the present embodiment, the plurality of dielectric constant layers 132a to 132f are formed using materials having different dielectric constants as additives, but the present invention is not limited to this, and the plurality of dielectric constant layers are mutually connected. You may form by changing the density | concentration of a dielectric material, or you may form by changing the mixing ratio of several materials mutually and mixing.

  For example, as a method of forming a plurality of dielectric constant layers by changing the concentration of the dielectric material, the concentration is gradually changed by mixing a predetermined dielectric material with a predetermined insulating main material little by little. Dielectric constant layers having different rates can be integrally formed.

  In this case, for example, a mold for the insulation reinforcing molded body 132 is used, and a predetermined insulating main material (silicone rubber, ethylene propylene rubber, etc.) and a predetermined additive having a high dielectric constant (titanic acid) are used in the mold. Barium or zinc oxide) or a predetermined additive having conductivity (carbon, metal powder, or the like) can be mixed to form the insulation reinforcing molded body 132.

  A specific procedure of the manufacturing method using the insulating main material and the additive is, for example, as follows. First, an insulating main material is poured into the portion of the dielectric constant layer 132a in the mold for the electric field relaxation molded body. Then, the insulating main material is poured from the portion of the dielectric constant layer 132b continuous to the dielectric constant layer 132a into the portion of the dielectric constant layer 132f, and the concentration of the portions of the dielectric constant layers 132b to 132f in the portions of the dielectric constant layers 132b to 132f. Reduce the thickness step by step. By such a molding method, the reinforced stress cone 130 in which a plurality of dielectric constant layers 132a to 132f having a lower concentration from the lower end side toward the upper end side, that is, a dielectric constant is integrated, is formed. it can.

  By the reinforcing stress cone 130 configured in this manner, the electric field stress at the end portion of the cable is relieved by the bell mouth portion 131 and the insulation reinforcing molded body 132.

  FIG. 3A is a diagram showing a simulation result of potential distribution in the terminal connection portion of the power cable using the reinforced stress cone according to the present embodiment, and FIG. 3B is a diagram showing the reinforced stress cone. 5 is a diagram showing a simulation result of potential distribution when the dielectric constant of a plurality of dielectric constant layers included in the insulation reinforcing molded body is made uniform (ε = 2.8 in this figure). In FIG. 3A and FIG. 3B, the potential distribution is indicated by broken equipotential lines.

  In the reinforced stress cone 130 shown in FIG. 3A, the plurality of dielectric layers 132a to 132f are integrally formed so that the dielectric constant decreases toward the upper end side which is the high voltage side. The equipotential lines are distributed substantially uniformly by the plurality of dielectric constant layers 132a to 132f having different rates.

  That is, in the configuration in which the reinforced stress cone 130 is provided in the terminal portion 110a of the high voltage power cable 110, the bell mouth portion 131 performs electric field relaxation of the high electric field portion generated in the terminal portion 110a of the power cable 110. The electric field stress that has increased in the formation along the surface of the bell mouth portion 131 can be distributed substantially evenly by the plurality of dielectric constant layers 132 a to 132 f in the insulation reinforcing molded body 132. Thereby, the electric field stress at the end of the high-voltage power cable 110 is alleviated.

  On the other hand, in the reinforced stress cone shown in FIG. 3B, since the dielectric constants of the plurality of dielectric constant layers 132a to 132f are made uniform, equipotential lines are concentrated on the surface portion of the bell mouth portion. Yes.

  Next, an example of a method for attaching the reinforced stress cone 130 will be described together with an example of a method for attaching the cable end connection portion.

  First, the end portion 110a of the power cable 110 in which the end connection portion 100 is formed is arranged at a predetermined position of the installation base 146 to which the support insulator 145 is attached, and the cable sheath 117 of the end portion 110a of the power cable 110, The outer semiconductive layer 115 and the cable insulator 113 are removed to a predetermined position, and the conductor lead bar 121 is connected to the conductor 111 exposed at the end of the power cable 110.

  Then, in the terminal portion 110a of the power cable 110, the cylindrical lower metal fitting 148, the support frame 142, the auxiliary metal fitting 127, the O-ring 128, the connecting member 129, and the diameter-enlarged holding material (spiral core) are expanded. The reinforced stress cones 130 are sequentially inserted.

  Then, after the support frame 142 is supported by attaching the support frame 142 to the support insulator 146, the bell mouth portion 131 of the reinforced stress cone 130 with the expanded diameter holding member is aligned with the lower end portion of the cable insulator 113. Specifically, the bell mouth 131 is aligned so as to straddle the outer semiconductive layer 115 and the cable insulating material 113.

  Then, while maintaining the alignment state of the bell mouth portion 131, the diameter expansion holding member is pulled out and is brought into pressure contact with the outer peripheral surface 113a of the cable insulator 113 and the outer peripheral surface 115a of the outer semiconductive layer 115, thereby reinforcing the stress cone 130. Is attached to the cable insulator 113.

  In addition, although not shown in figure, you may attach the reinforcement type | mold stress cone 130 by the diameter expansion process using a normal diameter expansion machine and a pipe in the case of an assembly.

  In addition, since the reinforced stress cone 130 has an inner diameter at the time of non-expanding sufficiently smaller than the outer diameter of the cable, the surface pressure at the interface between the reinforced stress cone 130 and the cable insulator 113 can be increased. Excellent withstand voltage is guaranteed.

  Thus, after attaching the reinforced stress cone 130 to the outer peripheral surface 113a of the cable insulator 113 with sufficient surface pressure, the distal end portion of the connecting member 129 is inserted into the notch portion 134a on the lower surface of the bell mouth portion 131 to connect the connecting member 129. The lower flange portion 129 b is airtightly joined to the auxiliary metal fitting 127, and this auxiliary metal fitting 127 is airtightly joined to the support frame 142 via the bolt 153.

  Then, a seal tape (not shown) is wound around the outer peripheral surface of the cylindrical main body portion 129a of the connecting member 129 and the outer surface of the bell mouth portion 131 of the reinforcing stress cone 130, thereby sealing between the two.

  Then, a soot pipe 125 attached with a cover 123 is inserted into the end portion 110a of the power cable 110, and the conductor lead bar 121 is pulled out from the cover 123 attached to the soot pipe 125. The lower end portion of the soot tube 125 is coupled to the support frame 142 via the bolts 144.

  Then, an insulating gas is sealed in the inner space 140 of the soot pipe 125 through a conductor lead rod passage (not shown), and the upper end of the lower fitting 148 that has been temporarily inserted is hermetically sealed to the auxiliary fitting 127 via the bolt 151 and the packing 154. To join.

  Then, the attachment of the cable terminal connection portion 100 is completed by airtightly connecting the lower end of the lower metal fitting 148 and the end of the cable sheath 117 by winding the tape-shaped sealing material 156.

  As described above, according to the present embodiment, the bell mouth portion 131 and the insulation reinforcing molded body 132 that relaxes the creeping electric field on the surface of the bell mouth portion 131, that is, the surface of the bell mouth upper portion 131b, are integrally formed. In addition, since the insulation reinforcing molded body 132 is integrally formed with the dielectric layers 132a to 132f having different dielectric constants arranged in the axial direction, the cable insulator of the power cable 110 to which a high voltage is applied. By simply mounting on 113, the creeping electric field stress generated on the surface of the bell mouth portion 131, that is, the surface of the bell mouth upper portion 131b can be alleviated by sharing the dielectric constant layers with different dielectric constants.

  Therefore, the reinforced stress cone 130 requires skill, unlike the capacitor cone using the conventional oil-immersed insulating paper, while maintaining a certain electric field relaxation effect equivalent to the capacitor cone using the conventional oil-immersed insulating paper. Assembling can be easily performed without shortening the assembling operation time.

  Further, since the bell mouth part 131 and the insulation reinforcing molded body 132 formed integrally with the reinforced stress cone 130 are each made of an elastic body, the conventional oil-immersed insulating paper is used when the terminal connection part 100 is formed. Unlike the capacitor cone used, it is not necessary to fill the cylindrical space between the cable end portion where the reinforced stress cone 130 is disposed and the soot tube with oil, and the working time can be shortened and the cylindrical shape can be reduced. Since the oil is not filled in the space, it is possible to reduce the weight of the end connection part 110 itself.

  Further, in the configuration of the termination connection portion 100 of the power cable 110 using the reinforced stress cone 130 according to the present embodiment, the termination processing of the premolded insulator compression type cable as a conventional premold connection portion is performed. Unlike the configuration, there is no need for a spring or an epoxy seat that presses the pre-molded insulator into the steel tube, so the number of parts for the spring or the epoxy seat is used as the terminal connection portion 100 of the power cable 110. Therefore, the cost can be reduced.

  In addition, since the plurality of dielectric constant layers 132a to 132f are formed of materials having different dielectric constants, the insulating reinforcing molded body 132 of the reinforced stress cone 130 can be easily manufactured only by using different materials. Can do.

  In the reinforced stress cone 130 according to the present embodiment, the bell mouth part 131 and the insulation reinforcing molded body 132 are integrally formed. However, the present invention is not limited to this, and the bell mouth part 131 and the insulating reinforcing molded body 132 are formed. A structure formed separately, a structure in which the insulation reinforcing molded body 132 itself is divided into a plurality of parts, and a bell mouth portion 131 and a part of the insulating reinforcing molded body 132 are integrally formed, and the other insulation The reinforcing molded body 132 portion may be formed integrally or divided into a plurality of parts.

  If the reinforced stress cone 130 is divided into a plurality of parts as described above, the division is made compact, and manufacturing, transportation to the site, construction, and the like are facilitated.

  In the case where the reinforced stress cone 130 is divided into a plurality of parts and molded, for example, the bellows part 131 and the insulating reinforcing molded part 132 that is in contact with the surface of the bellmouth part 131 are the most easily secured. (In this embodiment, the dielectric constant layer 132a) is integrally formed, and the dielectric constant layers 132b to 132f other than the dielectric constant layer 132a are integrally formed.

  As described above, the bell mouth portion 131 and the dielectric constant layer 132a are integrally formed because the insulation reinforcing molded body 132 has a function of reducing the electric field stress in the layering direction from the surface of the bell mouth portion 131. This is because it is desirable that at least the bell mouth portion 131 and the insulating reinforcing molded body 132 portion (dielectric constant layer 132a) adjacent to the bell mouth portion 131 are integrally formed.

  However, depending on the size and weight of the reinforced stress cone 130, the bell mouth portion 131 and the dielectric constant layer 132a may be integrally formed and the other dielectric constant layers 132b to 132f may be divided into a plurality of parts. Good. This is as described above.

  Moreover, although the insulation reinforcement molded object 132 in this Embodiment was formed with the six dielectric constant layers 132a-132f, it is not restricted to this, As long as it is two or more, it may be comprised by what layers. .

  Further, in the reinforced stress cone 130 according to the present embodiment, the dielectric constant layers 132a to 132f are reduced in the dielectric constant layers 132a to 132f toward the high voltage side, that is, toward the terminal end side of the power cable 110 in order to alleviate the electric field stress at the cable end. However, the present invention is not limited to this, and any dielectric can be used as long as it can relieve the creeping electric field stress that increases on the surface of the bell mouth portion 131 when the reinforced stress cone 130 is attached to a high voltage cable. The dielectric layer may have any dielectric constant.

  For example, the dielectric constant layers 132a to 132f of the insulation reinforcing molded body 132 are not configured so that the dielectric constant gradually decreases from the dielectric constant layer 132a toward the dielectric constant layer 132f, and the dielectric constant of each dielectric constant layer is arbitrarily set. It may be configured with a value to relieve the electric field stress at the end of the attached cable.

  Further, in this embodiment, the insulation reinforcing molded body 132 of the reinforced stress cone 130 is formed by the plurality of dielectric layers 132a to 132f so that the dielectric constant changes stepwise, but this is not limitative. Instead, the dielectric constant may be continuously changed.

  In this case, in order to continuously change the dielectric constant of the insulation reinforcing molded body, for example, the concentration of the high dielectric material is continuously changed, or the mixing ratio of a plurality of materials is continuously changed and mixed. You can do it. Thereby, the reinforcement molded object from which a dielectric constant changes continuously to an axial direction can be formed.

The fragmentary longitudinal cross-section which shows the structure of the termination | terminus connection part of the power cable using the stress cone for termination | terminus connection parts which concerns on one embodiment of this invention 1 is an enlarged cross-sectional view of the main part of the terminal connection part of FIG. 1 including the stress cone for the terminal connection part according to the present embodiment. (A) is a figure which shows the simulation result of the electric potential distribution in the termination | terminus connection part of the electric power cable using the reinforcement type stress cone which concerns on this Embodiment, (b) is an insulation reinforcement molded object in the same reinforcement type stress cone. The figure which shows the simulation result of the potential distribution when the dielectric constant of the several dielectric constant layers which has is made uniform Cross-sectional view of the main part showing an example of the structure of a terminal connection portion of a conventional power cable using a capacitor cone

Explanation of symbols

DESCRIPTION OF SYMBOLS 100 Cable terminal connection part 110 Electric power cable 110a Electric power cable terminal part 130 Reinforcement type stress cone 131 Bell mouth part 132 Insulation reinforcement molding 132a, 132b, 132c, 132d, 132e, 132f Dielectric constant layer 137 Outer peripheral surface 138 Interface

Claims (5)

A stress cone body that relaxes the electric field of the high electric field generated at the end of the power cable;
A reinforcing molded body that relaxes the creeping electric field on the surface of the stress cone body,
A stress cone for a terminal connection part, wherein the reinforcing molded body is formed so that the dielectric constant differs in the axial direction.   2. The stress cone for terminal connection according to claim 1, wherein the reinforcing molded body is formed so that a dielectric constant decreases from a low pressure side toward a high pressure side.   The stress cone for a terminal connection part according to claim 1, wherein the stress cone for the terminal connection part is formed integrally or divided into a plurality of parts.   The reinforcing molded body is formed by axially arranging a plurality of dielectric constant layers having different dielectric constants, and the plurality of dielectric constant layers are formed using materials having different dielectric constants, or 2. The stress for a terminal connection part according to claim 1, wherein the stress is formed by changing the concentration of dielectric materials with each other, or formed by changing the mixing ratio of a plurality of materials to each other. corn.   The reinforcing molded body is formed by continuously changing a concentration of a dielectric material, or formed by continuously changing a mixing ratio of a plurality of materials and mixing them. Item 6. The stress cone for terminal connection according to Item 1.

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