JP3181504B2 - Power cable connection - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a power cable connecting portion provided with an insulating bushing and an insulating tube.

[0002]

2. Description of the Related Art At a terminal connection portion of a power cable,
It is desirable that the cable shield side and the terminal junction box side be electrically separated from each other so that it is convenient to detect a short-circuit current at the time of an accident or a failure point by the Murray loop method or the like. Therefore, an insulating tube is inserted between the ground side of the insulating bushing and the cable protection tube. FIG.
Shows an end of a 66 kv CV cable slip-on type gas middle terminal as an example of a power cable connecting portion provided with this insulating tube. The inner surface of the upper half of the insulating bushing 1 made of epoxy resin has A shielding tube 2 is embedded, and a conductor extraction rod 4 is fixed to an upper metal fitting 3 attached to an upper end portion thereof through a conductor fixing metal fitting 5. A female contact 6 of a tulip contact type is attached to the lower end of the conductor lead bar 4. The female contact 6 is formed by arranging a large number of finger conductors in a cylindrical shape and bundling four peripheral portions with a coil spring. The inner surface near the lower end of the female contact 6 is gently projected to form a female fitting portion. ing. At the lower end of the insulating bushing 1, a ground-side lower shielding cylinder 7b integrated with the mounting flange 7a is embedded and molded.

[0003] The insulating bushing 1 having such a configuration is attached to an electric equipment case by bolting the mounting flange portion 7a to a case bottom plate 8 of the electric equipment. An insulating cylinder 10 is attached to the case bottom plate 8 via a metal adapter 9. On the other hand, the power cable 11 attached to the termination junction box includes a cable sheath 12, a shielding tape layer 13, an outer semiconductive layer 14, and a cable insulating layer 1.
5 are sequentially stripped, and the male connection terminal 17 is compression-connected to the exposed cable conductor 16. A pre-mold insulator 19 is mounted on the exposed insulating layer 15 via a semi-conductive tape mold 18. Reference numeral 19a denotes a semi-conductive stress cone integrally molded on the back surface of the pre-mold insulator 19, and the vicinity of the lower end thereof is fitted to the semi-conductive tape mold 18 and electrically connected thereto. Before the power cable 11 is mounted with the pre-mold insulator 19, the cable protection fitting 21, the pre-mold insulator compression device 22, and the like are fitted. The pre-mold insulator compression device 22 includes a washer 22a, a shaft spring 22b, a press fitting 22c, and a push pipe 22d.
The inner surface near the tip of the push pipe 22d is a tapered surface corresponding to the outer shape of the stress cone 19a. Further, a step (not shown) is provided in the middle of the inner surface of the cable protection metal fitting 21, and the washer 22 is provided.
a is configured such that the retreat is restricted by a certain amount or more by this step.

[0004] Inserting the end portion of the power cable 11 pre-treated as described above into the insulating bushing 1 and assembling it by connecting the cable protection fitting 21 to the flange portion 10a of the insulating cylinder 10 with a bolt, the male side connection is established. The fitting portion of the terminal 17 pushes open the female fitting portion against the force of the coil spring of the female contact 6, and is mounted and electrically connected thereto. Also, the pre-mold insulator 19 and the stress cone 19a
Are the shaft spring 22b, the press fitting 22c and the push pipe 22d of the pre-molded insulator compression device 22.
As a result, the tapered surface of the pre-mold insulator 19 is pressed against the tapered surface of the insulating bushing 1 to maintain the insulation strength. Reference numeral 23 denotes a grounding lead connecting between the shielding tape layer 13 of the cable and the washer 22a, and reference numeral 24 denotes a waterproofing portion formed between the cable sheath 12 and the cable protection fitting 21.

In the above, the lower shielding cylinder 7b, the mounting flange 7a and the adapter 9 are grounded through the case bottom plate 8 of the electric equipment. Further, the cable shielding layer 1 is interposed via the semiconductive tape mold 18 and the external semiconductive layer 14.
3 and a shaft spring 22b, a metal fitting 22c and a washer 22a made of a metal material of the pre-molded insulator compressing device 22, together with the cable protective metal 21 and the ground terminal seat. It is grounded through a ground wire (not shown) attached to 21a. In the power cable connection portion having such a configuration,
When a surge voltage enters the cable line due to switching surge or lightning, a device-side grounding system including a lower shielding cylinder 7b, a mounting flange 7a, and an adapter 9 grounded through a case bottom plate 8 of the electric device. , A stress cone 19a grounded through a ground wire attached to a ground terminal seat 21a, a shaft spring 22b of a pre-molded insulator compression device 22, a press fitting 22c, a washer 22a.
A voltage is induced between the cable and the cable-side grounding system composed of the cable protection fitting 21, and it is necessary to prevent discharge from occurring inside the connection portion due to the induced voltage.

FIG. 8 shows routes L1 to L4 that may cause a discharge between the above-mentioned grounded components.
The space between the components of both grounding systems is enlarged for convenience of explanation. L1: near the upper end of the outer surface of the stress cone 19a to near the inner surface of the lower end of the lower shielding cylinder 7b L2: lower end of the stress cone 19a or the inner surface of the semiconductive tape mold 18 to the adapter 9 L3: near the upper end of the press fitting 22c to the lower portion of the adapter 9 Inner surface near flange 9a L4: Outer surface of lower flange 9a of adapter 9 to outer surface of lower flange 10a of insulating tube L4 ': Inner surface of lower flange 9a of adapter 9 to inner surface of lower flange 10a of insulating tube 10 If a discharge occurs at L1, the stress cone 19a may be burned. Therefore, the insulation strength of L1 needs to be higher than the insulation strength of the route L3. Also, if a discharge occurs along the route L2, L3 or L4 ', it is difficult to discriminate it from the outside, so it must be avoided. Therefore, based on the idea of insulation coordination, each route L1
The insulation strengths SL1 to SL4 of L4 are designed so that SL1, SL2, SL3> SL4.

[0007]

As described above, in order to increase the insulation strength SL1, the length of the route L1 cannot be reduced. For this reason, the total length of the connection part becomes long, and it has been difficult to achieve compactness. In the case where the above L1 portion is short as in the case of an insulating bushing in a T-shaped cable head (see the embodiment of FIG. 1 described later).
Since the insulation strength on the mounting surface of the insulating cylinder was significantly reduced, the insulating tube could not be mounted. The present invention
It is an object of the present invention to provide a compact power cable connection part having a high dielectric strength.

[0008]

Means for Solving the Problems A first invention of the present invention is:
Insulated at open end of insulation bushing to which cable is connected
Connect a tube and connect a cable between this insulating tube and the cable sheath.
With a stress cone pressing mechanism connected with
Power cable connection, the insulating bushing
Surface near the open end of the
At the interface between the outer surface of the cone push pipe and the bushing
To prevent flashover between the grounding system on the cable side and the grounding system on the cable side.
For preventing flashover is provided
(Claim 1). Departure
The second invention of the present invention relates to an insulating bushing to which a cable is connected.
Connect the insulation tube to the open end of the
Power cable connected to sheath with cable protection bracket
An opening end of the insulating bushing,
Bushing side between the insulation tube attached there
Prevent flashover between grounding system and cable side grounding system
In order to prevent flashover, a reinforcing member
(Claim 3). The present invention
A third invention is an insulating bushing to which a cable is connected.
Connect the insulating cylinder to the open end of the
Cable with a cable protector
At the power cable connection with the
The inner surface of the insulation tube and the stress cone inside
Bushing side grounding system and cable between outer surface of push pipe
Cable to prevent flashing between
Characterized in that a loop-shaped flashover prevention reinforcing member is arranged.
(Claim 5).

[0009]

DESCRIPTION OF THE PREFERRED EMBODIMENTS In the present invention, a cable-side grounding system includes a cable sheath, a shielding tape layer, an external semiconductive layer, and a stress cone grounded through a ground wire attached to a ground terminal seat of a cable protection fitting. It is composed of a pre-molded insulator compression device and a cable protection fitting, and a conductive layer formed on the outer surface of the insulating bushing forms a part of a device-side grounding system (a bushing-side grounding system) . The tip of the cable-side grounding system means the tip of the stress cone that is electrically closest to the device-side grounding system. The boundary between the insulating members located between one end of the insulating bushing and the tip of the cable-side grounding system includes a boundary between one end of the insulating bushing and the insulating cylinder attached thereto, and an insulating bushing. And the interface of the stress cone push pipe located inside it.

In the present invention, the flash-prevention reinforcing member can be arranged at the boundary between the inner surface near one end of the insulating bushing and the outer surface of the stress cone push pipe. In this case, a ring-shaped groove can be formed on one of the outer surface of the stress cone push pipe and the inner surface near one end of the insulating bushing, and a flashover prevention reinforcing member can be inserted into this groove. In addition, the flash-prevention reinforcing member can be disposed at a boundary surface between one end of the insulating bushing and the insulating cylinder attached thereto. In this case, a ring-shaped groove is formed on one of the facing surface of the insulating bushing and the insulating cylinder,
A flashover prevention reinforcing member may be inserted into this groove.

Further, in the third invention of the present invention, a flash loop preventing reinforcing member having a closed loop shape is disposed on a boundary surface between an inner surface of the insulating cylinder and a stress cone pushing pipe located inside the insulating tube. You can also. The flash-prevention reinforcing member used in the present invention can be formed of an elastic insulator molded in a closed loop shape, for example, a ring shape. In this case, the elastic insulating material having a JIS Shore hardness of HS 40 to 70 degrees is used. It is desirable to use the body in a moderately compressed state.

[0012]

Embodiments of the present invention will be described below with reference to the drawings. In these drawings, the same parts as those in FIG. 7 are denoted by the same reference numerals, and detailed description thereof will be omitted unless necessary.

FIG. 1 shows an example in which the present invention is applied to a pre-molded insulation type T-branch connection part for a 66 kv class CV cable. In the figure, a T-shaped insulating bushing 3
A cylindrical electrode 31 is buried in 0. On the outer periphery of the central portion of the electrode 31, a conductor lead rod 32 extending in a vertical direction from the axis thereof is continuously provided. This conductor extraction rod 32
Penetrates through a bushing leg 30a made of an insulating material, and a tip of the bushing protrudes from a tip of the bushing leg 30a (not shown).

The insulating bushing 30 has tapered terminal receiving portions 30b and 30c formed on both sides in the axial direction, and a lower end of the lower terminal receiving portion 30c has a plurality of peripheral portions (in this example). In this case, the bolt 33 is screwed into the mounting bracket 30d embedded in six places) so that the insulating cylinder 3 is formed.
4 are attached. A bolt with a hexagonal hole is used as the bolt 33, and a cutout portion 34 a is formed on the lower outer periphery of the insulating cylinder 34. The surface of the insulating bushing 30 has upper and lower end faces and bushing legs 3.
A conductive paint is applied except for the outer surface of the conductive layer 30a.
e.

2 and 3 are provided on the upper end surface of the insulating cylinder 34.
As shown in FIG. 5, a ring-shaped groove 34c is formed inside the insertion hole 34b for the bolt 33, and a closed loop-shaped flashover prevention reinforcing member 35 is inserted therein. As a material of the flashover prevention reinforcing member 35, a material having high withstand voltage such as ethylene-propylene rubber, silicon rubber, or NBR is suitable, and the hardness is JIS Shore hardness of about HS 40 to 70 degrees. Things are used. When attaching the insulating cylinder 34 to the insulating bushing 30, the flashover preventing reinforcing member 35 is compressed and deformed by screwing the bolt 33, and its surface pressure greatly increases the dielectric strength at the interface between the insulating bushing 30 and the insulating cylinder 34. And exhibit a waterproof function.

The insulating bushing 30 has a bushing leg 30a which passes through a through hole provided in a case side plate 8a of an electric device, for example, a C-GIS, in an airtight manner, and is inserted into the case side plate 8a so as to be located in the C-GIS. It is attached and fixed by a device band 36 or the like. The tip of the conductor lead-out rod 32 is connected to an internal wiring (not shown) of the C-GIS, and the conductive layer 30 formed on the surface of the insulating bushing 30.
e is electrically connected to the device case side plate 8a via the device band 36 or the like.

Into the insulating tube 34 and the terminal receiving part 30c, a cable terminal part which has been subjected to terminal processing in advance is inserted and fixed. That is, the power cable (CV cable in this example) 11 to be connected has the cable sheath 12, the shielding tape layer 13, the outer semiconductive layer 14, and the distal end of the cable insulating layer 15, which are sequentially peeled to expose the exposed cable conductor 16.
The male connection terminal 17 has a compression connection and a wedge 17a
A pre-molded insulator 19 is attached near the tip of the exposed cable insulating layer 15.
A stress cone 19a integrally molded with the above is attached. A stopper 19b is fitted to the tip of the pre-mold insulator 19, and a stress cone compression device 22 including a stress cone pushing pipe 22d, a shaft spring 22b, and a washer 22a, and a cable protection fitting are provided on the back surface of the stress cone 19a. 21 is inserted. The stress cone push pipe 22d is made of an insulating material such as a glass-filled epoxy resin. The fitting and insertion of the stress cone compression device 22 and the cable protection metal fitting 21 are performed prior to the attachment of the pre-mold insulator 19 and the male connection terminal 17.

In the cable terminal portion subjected to the terminal treatment as described above, the male connection terminal 17 is located within the electrode 21 and the tapered surface of the pre-molded insulator 19 has the lower terminal receiving portion 3.
A bolt 37d inserted into the insulating bushing 30 so as to be in contact with Oc, and inserted into the flange portion of the cable protection metal fitting 21 is embedded in the insulating cylinder 34d.
Is fixed to the insulating bushing 30. In this case, when the bolt 37 is screwed into the mounting bracket 34d, the washer 22a is engaged with the stepped portion 21b formed on the inner surface of the cable protection bracket 21 and is prevented from descending beyond a certain limit. By
The tapered surface of the pre-mold insulator 19 is elastically pressed against the tapered surface of the terminal receiving portion 30c of the insulating bushing 30 via the stress cone pushing pipe 22d, and exhibits a high dielectric strength. The male connection terminal 17 is electrically connected by a spring-shaped conductive member such as a multi-ram band (trade name) fitted on the outer surface of the large-diameter portion elastically contacting the inner surface of the electrode 31. The upper end of the male connection terminal 17 is C
-Shaped retaining ring, a tray whose peripheral edge is hooked by the retaining ring, and
Is fixed to the inner surface of the electrode 31 by a falling-off prevention mechanism 17b including a bolt attached to the electrode 31.

Terminal receiving part 3 on the upper side of insulating bushing 30
0b is always closed by the insulating plug 40. The insulating plug 40 includes a pre-molded insulator 41 having a tapered surface corresponding to the terminal receiving portion 30b, an outer conductor 42 and an inner conductor 43 embedded and molded at upper and lower ends of the pre-molded insulator except for end faces, It consists of springs 44 embedded in the recesses of the outer conductor 42 and a cover plate 45 connected to the outer conductor 42 via these springs. It is attached to the insulating bushing 30 by screwing it into the mounting bracket 30f embedded in the location.

In the above, the semiconductive tape mold 18
And a semiconductive stress cone 19a connected to the cable shielding layer 13 via the external semiconductive layer 14, and a shaft spring 22b, a metal fitting 22c, and a washer made of a metal material in the pre-mold insulator compression device 22. 22a is grounded together with the cable protector 21 and the cable sheath 12 through a ground wire attached to the ground terminal seat 21a. Further, the conductive layer 30e formed on the surface of the insulating bushing 30 is grounded together with the device case via the device band 36 or the like. Therefore, the surface of the insulating bushing 30 and the cable sheath side are cut off by the insulating cylinder 34.

In this case, according to the prior art, when a surge voltage enters the cable line side or the equipment side, along the interface between the insulating bushing 30 and the insulating cylinder 34 between the outer surface of the lower end of the insulating bushing 30 and the stress cone 19a. Although practical use was impossible due to the danger of electric discharge, in this embodiment, between the insulating bushing 30 and the insulating cylinder 34,
Since the flash-prevention reinforcing member 35 is inserted in a compressed state, the dielectric strength at the interface between the insulating bushing 30 and the insulating cylinder 34 is significantly improved. Can be. By the way, 66kv
In the case of CV cable connection box, impulse 4
Although a withstand voltage of 0 kv is required, it has been confirmed that when this embodiment is applied, the dielectric breakdown does not occur up to an impulse of 75 kv.

In the present invention, as shown in FIG. 4, a ring-shaped groove 34c is formed in the upper end surface of the insulating cylinder 34 in a double manner concentrically inside the bolt insertion hole 34b. If the flashing prevention reinforcing members 35 are interposed therebetween, safety can be further improved in terms of withstand voltage and waterproof performance. Further, in the above description, the example in which the ring-shaped groove 34c is formed on the upper end surface of the insulating cylinder 34 has been described, but this groove may be provided on the lower end surface of the insulating bushing 30. In addition, in the present invention, as shown in FIG. 5, the mounting position of the flashover prevention reinforcing member 35 is set between the inner surface near one end of the insulating bushing 30 and the stress cone pusher 22d located inside the inner surface. May be used as the boundary surface. Also in this case, a ring-shaped groove is formed on the inner surface of the insulating bushing 30 or the outer surface of the stress cone pressing fitting 22d, and a part of the flashover prevention reinforcing member 35 is fitted therein, and the exposed surface thereof is It is desirable to interpose so as to close the gap between the insulating bushing 30 and the stress cone fitting 22d in close contact with the surface of the insulating member.

FIG. 6 shows an embodiment of the third invention of the present invention. In this embodiment, the flashlight preventing reinforcing member 3
Reference numeral 5 is interposed between the inner surface of the insulating tube 10 and the outer surface of the stress cone push pipe 22d located inside the insulating tube 10, and the other configuration is the same as that in FIG. In this embodiment, the insulation strength SL4 'of the inner surface of the insulating tube 10, that is, the route L4' in FIG. 8, can be made higher than the outer surface of the insulating tube 10, that is, the insulation strength SL4 of the route L4. Can be avoided.

It should be noted that the present invention is not limited to the above-described pre-molded insulation type T-branch connection portion or the slip-on type gas termination portion, but various terminal connection structures having an insulating cylinder connected between an insulating bushing and a cable protection fitting. Can be widely applied to boxes and intermediate junction boxes. As described above, in the present invention, the boundary surface between the insulating members located between one end of the insulating bushing forming the device-side grounding system and the tip of the cable-side grounding system, or the inner surface of the insulating cylinder and the inner surface thereof By interposing a flashover prevention reinforcing member at the boundary between the insulating member and the insulating member located at the position, it is possible to greatly increase the withstand voltage along the interface therebetween, so that the device is compact and has a high dielectric strength. A power cable connection can be obtained.

[0025]

According to the present invention, it is possible to obtain a compact power cable connecting portion having a high dielectric strength.

[Brief description of the drawings]

FIG. 1 is a longitudinal sectional view showing an example in which the present invention is applied to a pre-molded insulating T-branch connection portion for a CV cable.

FIG. 2 is a plan view of the insulating cylinder in FIG. 1 and a flashover preventing reinforcing member mounted on the insulating cylinder.

FIG. 3 is a longitudinal sectional view taken along the line III-III in FIG. 2;

FIG. 4 is a longitudinal sectional view showing another embodiment of the insulating tube and the flashlight preventing reinforcing member mounted on the insulating tube according to the present invention.

FIG. 5 is a longitudinal sectional view of a main part showing an embodiment in which a flashover prevention reinforcing member is inserted between an insulating bushing and a stress cone pushing pipe in the present invention.

FIG. 6 is a longitudinal sectional view of an essential part showing an embodiment in which a flashover prevention reinforcing member is interposed between an insulating cylinder and a stress cone pushing pipe in the present invention.

FIG. 7 is a vertical cross-sectional view of a slip-on type gas in-gas termination portion illustrating a conventional power cable connection portion.

FIG. 8 is an explanatory diagram showing a discharge route in FIG. 7;

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Insulating bushing 2 ... Inner shielding cylinder 3 ... Upper metal fitting 4 ... Conductor lead-out rod 5 ... Conductor fixing metal fitting 6 ... Female contact 7b ... Lower shielding cylinder 8 ... Case bottom plate of electrical equipment 8a ... Case side plate 9 Adapter 10 Insulation cylinder 12 Cable sheath 13 Shielding tape layer 14 External semiconductive layer 15 Cable insulation layer 16 Cable conductor 17 Male connection terminal 17b Prevention mechanism 18 Semiconductive tape mold 19 Premold insulator 19a Stress cone 21 Cable protection fitting 22 Premold insulator compression device 22a Washer 22c Press fitting 22d Stress cone push pipe 30 ... Insulating bushing 31... Electrode 32... Conductor extraction rod 34... Insulating cylinder 34 c. ...... equipment band 40 ...... insulation plug

Claims (6)

(57) [Claims] 1. An insulating bushing to which a cable is connected.
Connect an insulating tube to the open end, and connect this insulating tube to the cable
Cable with a cable protector.
In the power cable connection portion having a pressing mechanism, The inner surface near the opening end of the insulating bushing and the inside thereof
The boundary between the outer surface of the stress cone push pipe located at
The bushing-side grounding system and cable-side grounding system
Closed loop type flashover prevention to prevent flashover between
A power cable having a reinforcing member disposed thereon.
Connection. 2. An outer surface of the stress cone push pipe.
Any one of the inner surfaces near the opening end of the insulating bushing
A ring-shaped groove is formed on the side, and the flashover is prevented in this groove.
2. A reinforcing member for use is inserted.
The power cable connection described in the above. 3. An insulation bushing to which a cable is connected.
Connect an insulating tube to the open end, and connect this insulating tube to the cable
Power cable connection between the
In the continuation, The open end of the insulating bushing and attached thereto
A bushing-side grounding system and a cable
Closed loop to prevent flashover between side grounded systems
Characterized in that a flashover prevention reinforcing member is disposed.
Power cable connection. 4. The opposed insulating bushing and the insulating cylinder.
A ring-shaped groove is formed on one of the surfaces, and inside this groove
The flashover prevention reinforcing member is inserted in a compressed state
The power cable connection according to claim 3, characterized in that:
Department. 5. An insulating bushing to which a cable is connected.
Connect an insulating tube to the open end, and connect this insulating tube to the cable
Cable with a cable protector.
In the power cable connection portion having a pressing mechanism, An inner surface of the insulating tube and a stress coat located inside the inner surface.
Between the bushing side grounding system and the outer surface of the push pipe.
Close to prevent flashover between cable ground systems.
It features a loop-shaped flashover prevention reinforcing member.
Power cable connection. 6. The flashlight preventing reinforcing member has a closed loop shape.
It is made of an elastic insulator, and its JIS Shore hardness is HS40.
6. The method according to claim 1, wherein the angle is about 70 degrees.
A power cable connection according to any one of the preceding claims.