JP2011250509A - Air termination joint - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an air termination joint with stable performance, even if a high impulse voltage is applied, capable of preventing a dielectric breakdown caused by a triple junction which is generated when insulating oil, a cable insulator, and air contact each other, while eliminating the necessity of a corona shield at around the outer circumference of an upper fitting.SOLUTION: An inner space 170 is formed by an outer peripheral surface 141a of a cable insulator 141, an inner peripheral surface 110d of a porcelain tube 110, and a lower end surface 130a of an upper fitting 130. The inner space 170 is filled with insulation oil 180 in such a manner that a predetermined air layer 190 is left at the upper portion of the space. An air termination joint 100 has an inner shield 200 which is mounted in such a manner that it extends toward the inner space 170 from the lower end surface 130a of the upper fitting 130, and which covers the outer periphery of a conductor connection terminal 150. The inner shield 200, by submerging its rear end part into the insulation oil 180 by a predetermined depth, covers a triple junction P where the cable insulator 141, the insulation oil 180, and the air layer 190 contact each other.

Description

  The present invention relates to an air termination connection portion for a power cable, and more particularly to an air termination connection portion using insulating oil.

  An air termination connection is used to connect a bare wire such as an overhead wire or an insulated wire at the end of the cable.

  Patent Document 1 discloses an air terminal connection portion in which a conductor lead bar protruding from the top of the soot tube is attached to a soot tube upper metal fitting fixed to the top of the soot tube by a conductor fixing metal fitting.

  FIG. 1 is a partial cross-sectional view of a conventional air terminal connection for a high-voltage power cable.

  As shown in FIG. 1, in the air termination connection portion 1, the end of the cable 2 rises inside the soot tube 3 to form a termination. In the cable 2, the insulator is peeled off at the end thereof, and the conductor 4 is exposed. A conductor lead bar 7 is electrically connected to the conductor 4 of the cable 2 via a terminal 5 and a tulip contact 6.

  The leading end of the conductor lead-out rod 7 is drawn out through the conductor fixing bracket 8 provided at the top portion 3 a of the soot tube 3. The conductor fixing metal fitting 8 is attached to the iron pipe upper metal fitting 11 fixed to the top part 3 a of the iron pipe 3 with a bolt 12, and a corona shield 9 is provided so as to cover the conductor fixing metal fitting 8.

  On the other hand, each terminal portion including the conductor lead bar 7 expands and contracts due to changes in the current flowing in the cable 2 and the outside air temperature. At this time, the coefficient of thermal expansion of the conductor lead bar 7 and the soot tube 3 is greatly different. For this reason, this difference is absorbed, and the insulating oil 10 accommodated in the inside of the soot pipe 3 becomes the conductor lead bar 7 and the conductor fixing metal fitting 8. In addition, it is necessary to prevent leakage from between the conductor fixing metal fitting 8 and the tub tube upper metal fitting 11.

  Therefore, conventionally, the conductor fixing bracket 8 is covered with a washer 13 from above, and the washer 13 is fixed to the conductor fixing bracket 8 with a screw 14. An O-ring 15 is disposed between the washer 13 and the conductor fixing bracket 8 so as to surround the conductor lead bar 7. Further, an O-ring 16 is arranged on the mating surface portion between the conductor fixing metal fitting 8 and the tub tube upper metal fitting 11 at the outer peripheral portion of the conductor fixing metal fitting 8.

  Patent Document 2 discloses a cable termination connection portion formed at a connection portion between a cable and a device or a rising end of the cable.

  As shown in FIG. 2 of Patent Document 2, the cable termination connecting portion described in Patent Document 2 is a cylindrical corona shield 15 (Patent) in order to prevent the corona from being generated around the upper metal fitting 10 and the conductor lead bar 8. 2 of the document 2) is arranged so as to be supported by the upper metal fitting 10.

JP 2003-219549 A Japanese Patent Application Laid-Open No. 8-149647

  However, in such an air termination connection portion using conventional insulating oil, when the voltage is increased, the electrical performance changes due to the effect of the upper air layer inside the soot tube. In other words, when insulating the inside of the soot pipe at the end-of-air connection in insulating oil, the dielectric breakdown occurs at the triple junction (triple junction) where the insulating oil, the cable insulator, and the air as the gas layer come into contact with each other due to the high impulse voltage. And dielectric breakdown may occur from the inside of the air termination connection.

  In order to avoid this, the conventional air terminal connection portion has a large corona shield (see FIG. 1) on the outer periphery of the upper metal fitting (corresponding to the conductor fixing metal fitting 8 in FIG. 1 and equivalent to the upper metal fitting 10 in FIG. 2 of Patent Document 2). Corresponding to the corona shield 9 and corresponding to the corona shield 15 of FIG. However, such a corona shield has a drawback that it is large and difficult to manufacture. In addition, since a large corona shield is disposed, the installation area of the air termination connection portions arranged as a result is increased. Furthermore, the necessity of the corona shield and the difficulty in manufacturing the corona shield lead to an increase in the number of parts and an increase in the time for assembly work, and there is a problem that the cost cannot be reduced.

  The present invention has been made in view of such a point, and the insulating oil, the cable insulator, and the air (gas layer) are in contact with each other even when a high impulse voltage is applied while eliminating the corona shield on the outer periphery of the upper metal fitting. An object of the present invention is to provide an aerial termination connection portion that can prevent dielectric breakdown due to triple junction and has stable performance.

  The air terminal connection portion of the present invention includes a soot tube having a soot portion formed on the outer peripheral surface of a cylindrical soot tube main body and spaced apart in the longitudinal direction, an upper metal fitting for airtightly covering the top of the soot tube, and the soot tube A cable that rises inside and exposes a cable insulator and cable conductor by stripping the end portion to form a terminal end; and a conductor connection terminal attached to the cable conductor; An air termination connecting portion filled with insulating oil so as to form a layer, wherein the lower end surface of the upper metal fitting extends to the gas layer side and covers the outer periphery of the conductor connecting terminal A shield is provided, and the inner shield is configured to be provided so that the rear end is immersed in insulating oil.

  According to the present invention, even if a high impulse voltage is applied while eliminating the need for an external corona shield, dielectric breakdown due to triple junction where the insulating oil, the cable insulator, and the gas layer are in contact can be prevented, and the performance is stabilized. be able to.

Sectional drawing which shows the structure of the conventional air termination | terminus connection part Sectional drawing which shows the structure of the air termination | terminus connection part which concerns on embodiment of this invention The fragmentary sectional view which shows the upper part of the air termination | terminus connection part which concerns on the said embodiment Fig. 3 Equipotential distribution near the inner shield of the air termination connection part in Fig. 3. Partial sectional view of the case where the inner shield is removed from the aerial terminal connection according to the above embodiment Equipotential distribution diagram near the inner shield of the air termination connection part of FIG.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

(Embodiment)
FIG. 2 is a cross-sectional view showing the structure of the air termination connection portion according to the embodiment of the present invention. FIG. 3 is a partial cross-sectional view showing an upper portion of the in-air terminal connection portion of FIG. This embodiment is an example applied to an aerial terminal connection portion connected to a bare wire such as an overhead wire, an insulated wire, or the like.

  As shown in FIGS. 2 and 3, the aerial terminal connection portion 100 includes a soot tube 110 having a soot portion 110 b formed on the outer peripheral surface of a cylindrical soot tube body 110 a so as to be spaced apart in the longitudinal direction, and a top portion of the soot tube 110. The upper metal fitting 130 which covers 110c airtightly, and the upper conductor 120 fixed airtightly to the center part of the upper surface of the upper metal fitting 130 are provided.

  The tub tube 110 is made of an insulating material (for example, made of ceramics, rubber plastic, etc.), and is formed by providing a ridge portion 110b so as to project radially on the outer peripheral surface of the cylindrical tub tube body 110a. Yes.

  The upper conductor 120 is attached to the upper end surface of the upper metal fitting 130 with a bolt 125. The upper conductor 120 is connected to a high voltage line such as an overhead wire or a lead-in wire at the upper end, and is airtightly fixed to the center of the upper surface of the upper metal fitting 130 at the lower end.

  The upper metal fitting 130 is attached to the upper surface of the metal pipe upper metal fitting 131 fixed to the outer periphery of the top 110c of the metal pipe 110 with a bolt 132 so as to airtightly cover the top 110c of the metal pipe 110.

  The cable 140 is sequentially formed on a cable conductor 142 from a cable inner semiconductive layer (not shown), a cable insulator 141 made of crosslinked polyethylene, a cable outer semiconductive layer 143, a metal cable shielding layer 144, a vinyl chloride sheath, and the like. The cable sheath 145 to be formed is provided. The end portion of the cable 140 having such a configuration is stepped to sequentially expose the cable shielding layer 144, the cable outer semiconductive layer 143, the cable insulator 141, and the cable conductor 142, thereby forming a terminal end portion 140a. is doing.

  The air end connection portion 100 rises inside the soot tube 110 and is compressed by the cable 140 and the cable conductor 142 forming the end portion 140a, and the tip portion penetrates the upper metal fitting 130 and is electrically connected to the upper conductor 120. A conductor connection terminal 150 to be connected, and a tape connection layer 160 wound over the outer periphery of the conductor connection terminal 150 and the tip of the cable insulator 141 are provided.

  The conductor connection terminal 150 electrically connects the cable conductor 142 of the terminal end 140 a of the cable 140 to the upper conductor 120.

  The tape winding layer 160 is made of, for example, a self-bonding chloroprene rubber tape, and is formed across the outer periphery of the conductor connection terminal 150 and the cable insulator 141.

  The outer peripheral surface 141 a of the cable insulator 141, the inner peripheral surface 110 d of the soot tube 110, and the lower end surface 130 a of the upper metal fitting 130 form an internal space 170 that is sealed inside the soot tube 110.

  The internal space 170 is filled with an insulating oil 180 so that a predetermined air layer 190 (gas layer) remains in the upper portion. That is, the insulating oil 180 filled in the internal space 170 is filled so as to leave a predetermined amount of the air layer 190 above the oil surface 180a of the insulating oil 180, not so-called full-surface oil that fills the entire internal space 170. The For this reason, the position of the oil surface 180a is determined by the amounts of the insulating oil 180 and the air layer 190. The air layer 190 is determined in such an amount that the pressure inside the soot tube 110 does not increase more than a predetermined amount with respect to the expansion of the insulating oil 180 when energized. In the present embodiment, the oil surface 180 a of the insulating oil 180 is a position that does not cover the tape winding layer 160.

  Examples of the insulating oil 180 include silicone oils that have high performance stability and are not easily flammable, such as dimethyl silicone oil and methylphenyl silicone oil.

  The in-air terminal connection unit 100 includes a cylindrical inner shield 200 that covers the outer periphery of the conductor connection terminal 150 and the cable insulator 141 at the distal end of the duct 110.

  The inner shield 200 includes a conductive shield tube main body 200a and a flange portion 200b. The flange portion 200b is screwed to the lower end surface 130a of the upper metal fitting 130 with a screw 201. The shield cylinder main body 200a has a full cylinder length in which the flange portion 200b is attached to the lower end surface 130a of the upper metal fitting 130 and extends toward the internal space 170, and the rear end portion (lower side in the drawing) is sufficiently immersed in the insulating oil 180. . Hereinafter, the total cylinder length of the shield cylinder main body 200a is referred to as the total cylinder length of the inner shield 200.

  The inner shield 200 covers at least the triple junction P where the cable insulator 141, the insulating oil 180, and the air layer 190 (gas layer) are in contact. The inner shield 200 can cover the triple junction P by setting the rear end of the cylinder to be fully immersed in the insulating oil 180.

  As described above, the oil level 180a moves up and down the internal space 170 due to the expansion / contraction of the insulating oil 180 during energization. For this reason, the internal space 170 is moved up and down in the axial direction of the cable 140 also at the position of the triple junction P where the cable insulator 141, the insulating oil 180, and the air layer 190 are in contact. Regardless of the position of the triple junction P that moves up and down the internal space 170, the inner shield 200 always covers the triple junction P and has a full cylinder length that is immersed below the oil level 180a by a predetermined depth.

  Here, the overall length of the inner shield 200 and the length of the inner shield 200 immersed in the insulating oil 180 are, for example, a ratio of 1: (1/3). The reason will be described below.

  Considering only the electrical performance, it is better that the amount of the insulating oil 180 is large. However, as the amount of the insulating oil 180 increases, the cost increases and the temperature cannot be changed. Therefore, the position of the oil level 180a is first determined depending on the installation status of the air end connection unit 100. The total length of the inner shield 200 is determined by the following technical factors.

  (1) The rear end portion of the inner shield 200 (the lower side of the oil level 180a in FIG. 3) is sufficiently immersed in the insulating oil 180.

  By providing the inner shield 200, the electric field at the R portion at the rear end of the inner shield 200 is increased. Therefore, the rear end portion where the electric field becomes high needs to be immersed in the insulating oil 180 having a higher insulation strength than the air layer 190. The electrical performance is stabilized by immersing the rear end portion in the insulating oil 180.

  (2) The distance between the inner shield 200 and the ground side is sufficiently large.

  If the total length of the inner shield 200 is made longer than necessary, the distance from the ground side is shortened, and the electric field applied to the rear end portion of the inner shield 200 is increased, so that the insulation strength is lowered. Therefore, also from this point, the rear end portion of the inner shield 200 needs to be covered with the insulating oil 180 having high insulation strength.

  In the present embodiment, the oil surface 180 a of the insulating oil 180 is a position that does not cover the rear end portion 160 a of the tape winding layer 160.

  Further, the inner diameter and the outer diameter of the cylindrical inner shield 200 are dimensions that do not contact any of the outer peripheral surface 141 a of the cable insulator 141 and the inner peripheral surface 110 d of the soot tube 110. Further, in FIGS. 2 and 3, the inner diameter is not in contact with the tape winding layer 160. More specifically, the inner diameter of the inner shield 200 is closer to the outer peripheral surface 141a of the cable insulator 141 than the intermediate position between the outer peripheral surface 141a of the cable insulator 141 and the inner peripheral surface 110d of the soot tube 110, and the cable insulator. Since the electric field is less likely to enter the position of the triple junction P in the inner shield by disposing it at a position that does not contact the outer peripheral surface 141a of 141, it has been found that this is more preferable in terms of shielding.

  As shown in FIG. 2, an annular bottom metal fitting 211 is attached to the bottom 110 e of the soot tube 110 with a bolt 212. The annular bottom fitting 211 attaches the soot tube 110 to a support frame (not shown) with a support insulator (not shown) interposed.

  A stress cone 220 is attached to the outer periphery of the cable insulator 141. The stress cone 220 is located in a lower position in the sealed internal space 170 between the outer peripheral surface 141a of the cable insulator 141 and the inner peripheral surface 110d of the soot tube 110, and the cable insulator 141 outer peripheral surface 141a and the cable outer half. The conductive layer 143 is disposed across the outer peripheral surface.

  The stress cone 220 shown in FIG. 2 is a hardware-integrated stress cone as one embodiment. The metal-integrated stress cone 220 includes a rubber-made stress cone main body 221 and a metal fitting 222 provided integrally on the rear end side (lower side in FIG. 2) of the stress cone main body 221, and has a cylindrical shape as a whole. Presents.

  The stress cone main body 221 includes a cylindrical semi-conductor portion 223 made of rubber-like elasticity such as silicone rubber disposed on the rear end side (lower side in the drawing), and the tip side (upper side in the drawing) of the semi-conductor portion 223. ) And a cylindrical insulator portion 224 made of a rubber-like elastic body such as silicone rubber formed so as to be concentrically connected to the semiconductor portion 223 and to cover the semiconductor portion 223. I have. The stress cone main body 221 is integrated by a mold so as to cover the distal end side of the metal fitting 222. Also, the tip of the semiconductive portion 223 extends from the inner peripheral portion (rising portion) near the tip of the semiconductive portion 223 to reduce the electric field at the tip of the cable outer semiconductive layer 143. It has a shape that is curved in a bell mouth shape that gradually increases in diameter toward the outer periphery of the portion.

  The metal fitting 222 is provided so as to be in electrical contact with the semi-conductor portion 223 of the stress cone body 221 on the front end side (upper side in FIG. 2), and the rear end side (lower side in FIG. 2) is on the bottom metal fitting 211. The adapter 212 is fixed to the upper surface of the adapter fitting 225 by a bolt 212. By setting the bottom metal fitting 211 to the ground potential, the semiconductive portion 223 of the stress cone becomes the ground potential, and the electric field at the tip of the cable external semiconductive layer 143 can be reduced. Since the stress cone 220 is provided to relieve the electric field at the tip of the cable outer semiconductive layer 143, the stress cone 220 is not limited to the structure in which the metal fitting 222 of FIG. As long as it plays, the structure which does not have the metal fitting 222 may be sufficient.

  Hereinafter, the inner shield 200 of the air termination connection part 100 configured as described above will be described.

  FIG. 4 is an equipotential distribution diagram in the vicinity of the inner shield 200 of the air termination connection part 100 of FIG. 5 and 6 are diagrams for explaining the function of the inner shield 200, and FIG. 5 is a partial cross-sectional view in the case where the inner shield 200 is removed from the air termination connection portion 100 of FIG. 6 is an equipotential distribution diagram of FIG.

  FIG. 5 corresponds to the structure of a conventional air termination connection portion that does not have the internal shield 200, and FIG. 6 is an equipotential distribution diagram thereof.

  As shown in FIG. 6, in the conventional air termination connection portion that does not have the inner shield 200, the electric field distribution is such that equipotential lines spread radially along the axial direction of the upper metal fitting 130 and the cable 140. In particular, the electric field concentrates around the lower end surface 130a of the upper metal fitting 130 (see FIG. 6a). The place where the electric field concentrates at the lower position of the upper metal fitting 130 is a triple junction P of the insulating oil 180, the cable insulator 141, and the air layer 190 in the internal space 170 in the soot tube 110 of the air termination connection portion shown in FIG. It is near.

  That is, the triple junction P is present below the upper metal fitting 130, and the electric field concentrates on the triple junction P. The triple junction P is vulnerable to electric field concentration, tends to cause dielectric breakdown, and may cause dielectric breakdown from the inside of the air termination connection portion. In the conventional example, without paying attention to the above-mentioned triple junction P, the outer periphery of the upper metal fitting of the air end connection portion is simply a corona shield (see the corona shield 9 in FIG. 1 and the corona shield 15 in FIG. 2 of Patent Document 2). Covering prevented the generation of air discharge. However, the corona shield on the outer periphery of the upper metal fitting has a drawback that it is large and difficult to manufacture.

  In the present embodiment, the air end connection part 100 is attached to the lower end surface 130a of the upper metal fitting 130 with a cylindrical inner shield 200 that covers the outer periphery of the conductor connection terminal 150 and the cable insulator 141 in the duct 110. The shield 200 covers the triple junction P where the cable insulator 141, the insulating oil 180, and the air layer 190 are in contact with each other by immersing the rear end portion in the insulating oil 180 at a predetermined depth. As shown in FIG. 4 a, the electric field distribution is such that equipotential lines spread radially from the upper metal fitting 130 through the inner shield 200 along the axial direction of the cable 110.

  In particular, the internal shield 200 attached to the upper metal fitting 130 prevents the equipotential lines from reaching the lower side on the lower end surface 130 a of the upper metal fitting 130. That is, no electric field is applied to the triple junction P existing below the upper metal fitting 130. Since there is no electric field concentration at the triple junction P, it is possible to realize the aerial termination connection portion 100 with stable performance without providing a corona shield.

  As described above in detail, the air terminal connection portion 100 of the present embodiment is disposed on the central axis of the cylindrical soot tube 110, and the top conductor 120 protrudes from the soot tube 110, and the upper conductor 120. Is connected to the top conductor 120 via the conductor connector. The upper metal fitting 130 is fixed to the top of the steel pipe, the cable 140 rises inside the steel pipe 110 and forms a terminal portion, and the conductor conductor is connected to the cable conductor 142 via the conductor connector. And a tape connection layer 160 wound over the outer periphery of the conductor connection terminal 150 and the cable insulator 141. The outer peripheral surface 141a of the cable insulator 141, the inner peripheral surface 110d of the soot tube 110, and the lower end surface 130a of the upper metal fitting 130 form an internal space 170, and a predetermined air layer 190 is left in the internal space 170 at the top. Is filled with insulating oil 180. The aerial terminal connection portion 100 includes an internal shield 200 that extends from the lower end surface 130 a of the upper metal fitting 130 toward the internal space 170 and covers the outer periphery of the conductor connection terminal 150. The inner shield 200 covers the triple junction P where the cable insulator 141, the insulating oil 180, and the air layer 190 are in contact with each other by immersing the rear end portion in the insulating oil 180 at a predetermined depth.

  Thereby, since the electric field is not concentrated at the triple junction P, an air termination connection portion having stable performance can be realized without providing a corona shield. Therefore, when a corona shield is not provided, a more compact aerial termination connection can be realized, and when a plurality of aerial termination connections are aligned and installed, the mutual correlation distance can be reduced.

  Further, since it is not necessary to provide a corona shield, the structure of the upper metal fitting is simplified, and the cost can be reduced in combination with shortening of the assembly work time.

  In addition, after taking the structure of the air termination | terminus connection part 100 of this Embodiment, it is also possible to provide a corona shield further. If comprised in this way, it can apply to the aerial termination | terminus connection part of the applied voltage whose system voltage is higher than the conventional aerial termination | terminus connection part using a corona shield.

  The above description is an illustration of a preferred embodiment of the present invention, and the scope of the present invention is not limited to this. In the above-described embodiment, the conductor connection terminal 150 of the cable conductor of the air termination connection portion has been described with the structure in which the inner shield 200 is attached to the lower surface of the upper metal fitting 130. However, the inner shield may be integrated with the upper metal fitting.

  In the above-described embodiment, the inner shield 200 has been described as being conductive. However, in order to obtain an equipotential distribution such that an electric field does not enter the triple junction as shown in FIG. 4, at least the surface of the inner shield 200 is used. May be electrically conductive and may be in electrical contact with the upper metal fitting 130. For example, the inner shield 200 may be formed of an insulating material so that a conductive paint is electrically contacted with the upper metal fitting 130 on the surface. May be provided.

Further, the gas layer has been described with an air layer, as long as the insulating oil and a different dielectric constant, a gas other than air (e.g., nitrogen gas or SF ₆ insulating gas such as a gas) may be used. However, on the condition that a gas layer such as an air layer 190 is provided on the upper surface of the oil surface 180a of the insulating oil 180 in the soot tube 110, and that the rear end portion of the inner shield 200 is always immersed in the insulating oil 180. To do.

  In the above-described embodiment, since the oil surface 180a of the insulating oil 180 is in contact with the cable insulator 141, attention is paid to the triple junction P where the cable insulator 141, the insulating oil 180, and the air layer (gas layer) 190 are in contact. However, when the insulating oil is filled up to a position where the oil surface 180a of the insulating oil 180 is in contact with the tape winding layer 160, that is, when the triple junction of the tape winding layer 160, the insulating oil 180, and the air layer (gas layer) 190 is formed. The same effect can be obtained.

  The air termination connection part according to the present invention can be applied to an air termination connection part using insulating oil, and is useful as an air termination connection part for a power cable.

DESCRIPTION OF SYMBOLS 100 Air termination | terminus connection part 110 Saddle pipe 110a Saddle pipe main body 110b Saddle part 110c Top part 110d Inner peripheral surface 120 Upper conductor 130 Upper metal fitting 140 Cable 140a Termination part 141 Cable insulator 141a Outer peripheral surface 142 Cable conductor 150 Conductor connection terminal 160 Tape winding layer 160a Rear end 170 Internal space 180 Insulating oil 180a Oil level 190 Air layer 200 Internal shield 200a Shield tube body 200b Flange

Claims (3)

A soot tube having a soot portion formed on the outer peripheral surface of the cylindrical soot tube main body and spaced apart in the longitudinal direction;
An upper metal fitting airtightly covering the top of the soot tube,
A cable that rises inside the soot tube, and the cable insulator and cable conductor are exposed by stepping off the end portion to form a terminal portion, and
A conductor connection terminal attached to the cable conductor, and an air terminal connection portion filled with insulating oil so as to form a gas layer in the upper portion of the soot tube,
A lower end surface of the upper metal fitting is disposed to extend to the gas layer side, and includes an inner shield that covers an outer periphery of the conductor connection terminal,
The inner shield is an aerial terminal connection portion provided so that a rear end portion is immersed in insulating oil.   The aerial terminal connection part according to claim 1, wherein the inner shield has a cylindrical shape, at least a surface of which is conductive, and is in electrical contact with the upper metal fitting. The air terminal connection part according to claim 1 or 2, wherein the gas layer includes an air layer.

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