JPH1023621A - Cable head with disconnecting function - Google Patents

Abstract

PROBLEM TO BE SOLVED: To apply a large current with a compact construction and avoid the unexpected fall-off by a method, wherein a conductor connection part and the conductor connection part of an inner conductor are electrically connected to the outer circumference near the one end of a connection conductor plug and to the outer circumference near the other end of the connection conductor plug respectively with multicontact contactors. SOLUTION: A calking metal fitting 31 is put on the tip of a cable conductor 11a, and the calking metal fitting 31 and the tip of the cable conductor 11a are pushed into a plug 32 to connect the cable conductor 11a firmly to the plug 32 with the calking metal fitting 31 therebetween. The cable conductor 11a to which the plug 32 is attached is inserted into the plug insertion part 30a of a shielding metal fitting 30 and connected to the shielding metal fitting 30 with a multicontact contactor 33. A connection conductor plug 40 is pushed up to a required position by a pushing part, inserted into the recess of the connection conductor plug 40 and electrically connected to a conductor connection part 21, or the plug insertion parts 21b and 30b of the shielding metal fitting 30 with pre-attached multicontact contactors 41 by the compression contact.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a cable head having a disconnection function suitable for a power cable directly connected to a sealed electric device.

[0002]

2. Description of the Related Art A power cable is subjected to a withstand voltage test on site after a new cable line construction work, a system change work, or a repair work. In addition, the insulation performance of power cables may deteriorate gradually during long-term use, leading to dielectric breakdown. In particular, CV cables, which have been frequently used recently, may not be used depending on the manufacturing conditions and usage environment. Insulation performance may deteriorate in a relatively short period of time due to the water tree generated in the water, and various characteristic tests such as a withstand voltage test, corona test, and leakage current test are performed to diagnose the dielectric strength of the power cable. Done. There are AC withstanding voltage tests and DC withstanding voltage tests in power cable withstanding voltage tests.In the former AC withstanding voltage test, as the cable line length increases, the charging current of the line increases, and the transformer and other components are charged. Since the size of the power equipment becomes large and implementation becomes difficult,
Generally, the latter DC withstand voltage test is performed. By the way, recently, from the viewpoint of reducing the land of substations and improving the reliability of power transmission and distribution, a sealed type in which electrical devices such as switchgears and transformers are housed in an equipment case together with an insulating medium such as gas and oil. Electric equipment has been widely adopted, but since these high-voltage parts are not exposed to the outside of the equipment case, power cable lines with both ends directly connected to the closed electric equipment. In the case of (1), when conducting a withstand voltage test or the like, it is necessary to remove gas or oil from the equipment case and to attach an adapter for power application, and there is a problem that many man-hours and time are required. In order to solve such a problem, a T-shaped cable head with a DC charging function as shown in FIG. 5 has been developed and put to practical use.

In FIG. 5, an inner conductor 2 and a shield 3 are embedded and molded in an insulating bushing 1. The inner end of the inner conductor 2 and the shield 3 are electrically connected by a detachable connection conductor plug 4. A pre-molded insulator 5, shielding electrodes 6 and 7 molded at the inner and outer ends thereof, and a spring 8 are provided on the outer shielding electrode 7 in a tapered hole opened on the surface of the insulating bushing 1 opposite to the inner conductor 2. And an insulating plug 10 comprising a lid 9 attached through the plug. The cable terminal 12 crimped and fixed to the end of the cable conductor 11a of the power cable 11
Is electrically connected to the shielding fitting 3 via a contact 13 such as a tulip contact in a conductive sleeve 3a extending downward of the power cable 11 through a tapered hole opened on the lower surface of the insulating bushing 1. A stress cone 14 placed on the insulator 11b is mounted.
Three T-shaped cable heads having such a configuration are mounted side by side adjacent to the case side plate 15 of a sealed electric device such as GIS, and one end of the inner conductor 2 of each T-shaped cable head is insulated in the device case. It protrudes from inside the bushing 1 and is used by being connected to a high-voltage conductor (not shown) on the device side. Therefore, in a normal use state, the power cable 1
1 from the cable conductor 11a and the cable terminal 1
2, the contact 13, the shield 3, the connecting conductor plug 4, and the internal conductor 2 are supplied to the high-voltage conductor on the device side. An insulating plug 10 and a stress cone 14 are attached to the opening of the insulating bushing 1 to maintain a necessary dielectric strength.

[0004] In order to test the withstand voltage of the power cable 11 directly connected to the sealed electric device in this way, FIG.
As shown in (2), the insulating plug 10 and the connecting conductor plug 4 of the power supply port are removed, and the end of the test lead cable 17 is connected. In this case, a disconnecting insulating plug 16 is attached in place of the connecting conductor plug 4, and a distal end of a test lead cable 17 and a stress cone 18 are inserted in place of the insulating plug 10, and a distal end of the cable conductor 17 a is inserted. Is electrically contacted to the inner surface of the shield 3 via a spring.
In this state, when a test power supply is connected to the other end of the test lead cable 17 and a predetermined DC voltage is applied, the test voltage is changed to a cable conductor 17a, a contact 19, Shield 3, contact 13, cable terminal 12
Is applied to the cable conductor 11a of the cable under test, but since the inner conductor 2 is cut off from the shield fitting 3 by the disconnection insulating plug 16, no voltage is applied to the high-voltage conductor on the sealed electric device side. Not done. As described above, the use of the T-type cable head with the DC power application function allows the device to be opened without opening the case of the sealed electrical device, treating the insulating medium, and applying DC voltage to the device side. A DC withstand voltage test of the directly connected cable can be performed, and other tests can be performed efficiently.

[0005]

However, in the T-shaped cable head having the above-described structure, a finger-type contact is used to connect the shielding bracket 3 to the cable terminal 12, so that a large current is supplied. Therefore, there has been a problem that it is not easy to adapt to the withstand current test, and the overall dimensions and weight are also large. Further, if a pulling force acts on the cable, the cable may fall off. However, there is a problem that the structure and mounting of the dropout prevention mechanism for preventing the dropout are not easy. The present invention solves such a conventional technical problem, and is compact and capable of conducting a large current.Also, even if a pulling force acts on the cable, the cable with a disconnection function that does not inadvertently come off may be provided. It is an object to provide a head.

[0006]

According to the present invention, there is provided a cable head having a disconnection function, comprising: an inner conductor having a conductor connection portion and a conductor lead portion; and a shield having a conductor connection portion for connecting a cable conductor in an insulating bushing. The metal fittings are arranged insulated so that the axes of the conductor connection portions are located on the same line, and a plug insertion hole is formed in an insulating bushing between these conductor connection portions. Forming a tapered opening in the insulating bushing on the outer end side of the axis of the part,
A plug fixedly inserted through a wedge fitting near the distal end of a cable conductor in a cable head in which a connection conductor plug is detachably inserted into the plug insertion hole, and both ends of the connection are conductively connected to the respective conductor connection portions. Between the conductor connection portion of the shielding fitting into which it is inserted, between the conductor connection portion on the other end side of the shielding fitting and the outer periphery near one end of the connection conductor plug inserted therein, and between the conductor connection portion of the internal conductor. The part and the outer periphery near the other end of the connecting conductor plug inserted therein are electrically connected to each other by multi-contact contacts.

[0007]

DESCRIPTION OF THE PREFERRED EMBODIMENTS In a cable head with a disconnection function according to the present invention, during normal operation, a conductor plug for connection is inserted into a plug insertion hole to conduct electricity between an internal conductor and a conductor connection portion for connecting a cable conductor. When connecting the cable to the equipment side and using it electrically, if you do not want to apply voltage to the equipment side, as in the DC withstand voltage test, remove the connection conductor plug from the plug insertion hole, Instead, insert a disconnecting insulation plug and apply voltage from the other end of the cable, or remove the connection conductor plug from the plug insertion hole, and then attach a conductive plug and insulation reinforcement to the test lead. A cable can be inserted and a test voltage can be applied. In the present invention, a dropout prevention mechanism can be attached between the cable conductor and the conductor connection portion of the internal conductor. As this dropout prevention mechanism, a tightening ring attached to the conductor connection part of the inner conductor,
It is possible to use a nut fixed to a wedge fitting at the end of the cable conductor and a retaining bolt connecting the nut and the tightening ring. In addition,
The nut may be formed integrally with the wedge fitting.

[0008]

Embodiments of the present invention will be described below with reference to the drawings. In these figures, the same parts as those in FIGS. 5 and 6 are denoted by the same reference numerals, and description thereof will be omitted unless necessary. FIG. 1 is a longitudinal sectional view of an embodiment of a cable head with a disconnection function of the present invention, and FIG. 2 is a plan view of the cable head with its insulating plug removed. In these figures, an internal conductor 20 and a shield 30 are insulated and disposed at an appropriate interval in an insulating bushing 1 made of epoxy resin or the like, and are integrally molded. The internal conductor 20 includes a conductor connecting portion 21 having a shielding function, and a conductor lead portion 22 extending in a direction orthogonal to the axis of the conductor connecting portion 21. The conductor connecting portion 21 has a large-diameter plug insertion portion 21a on the upper side, and a slightly smaller-diameter plug insertion portion 21b on the lower side. The tip of the conductor lead-out portion 22 projects from the tip of the insertion portion 1a of the insulating bushing 1 in the device case. The shielding fitting 30 has a large-diameter plug insertion portion 30 on the lower side.
a, and on the upper side, a stopper insertion part 3 having a considerably smaller diameter.
0b.

The conductor connecting portion 21 of the internal conductor 20 and the shielding fitting 30 are arranged such that their axes are located on the same line. Insulating bushing 1 is formed with tapered openings 1b and 1c that open outward (up and down in FIG. 1) on the same line as the axis, and between conductor connecting portion 21 and shielding metal 30. A tapered plug insertion hole 1d whose diameter decreases toward the shielding fitting 30 is formed. An insulating plug 10 is attached to the upper tapered opening 1b, and a stress cone 14 covering the insulator 11b of the power cable 11 is attached to the lower tapered opening 1c. A plug 32 is fitted and fixed to the end of the cable conductor 11 a of the power cable 11 via a caulking fitting 31. The plug 32 is pressed into contact with the plug insertion portion 30a of the shield fitting 30 by a multi-contact type contact 33 such as a multi-ram band attached to a groove on the outer periphery thereof, so that the space between the cable conductor 11a and the shield fitting 30 is electrically conductive. Connected. The shield metal 30 and the conductor connection portion 21 of the internal conductor 20 are conductively connected by a connection conductor plug 40. The connecting conductor plug 40 has a cylindrical shape in the vicinity of the upper end and the lower end, and has a tapered shape in the middle corresponding to the plug insertion hole 1d, and is mounted in a cylindrical outer circumferential groove near the upper and lower ends. The multi-contact type contacts 41 and 42 such as a multi-lamb band are pressed into contact with the conductor connection portion 21 or the plug insertion portions 21b and 30b of the shielding fitting 30.

A drop-out prevention mechanism 50 is provided between the cable conductor 11a and the conductor connection portion 21 of the internal conductor 20. As shown in FIG. 3, the drop-out prevention mechanism 50 includes a tightening ring 51 attached to the conductor connecting portion 21 of the inner conductor 20 and a wedge fitting 3 at the tip of the cable conductor 11a.
1 comprises a nut 52 locked to the nut 1 and a retaining bolt 53 connecting the nut 52 and the tightening ring 51. The tightening ring 51 includes a tightening portion 51a threaded on the outer surface, and a pressing portion 51b protruding from the lower surface and inserted into a concave portion formed in the connection conductor plug 40,
At the center thereof, a retaining bolt insertion hole 51c is formed, and around the retaining bolt insertion hole, a plurality of boss holes 51d for inserting a detachable tool are formed. In the upper half of the retaining bolt insertion hole 51c, a reverse screw for attaching a removal tool is cut. The lower surface of the pressing portion 51b is reduced in diameter to a smaller diameter than its head 53a so that the retaining bolt 53 does not come off. The head 53 of the retaining bolt 53
a is formed with a hexagonal hole 53b for mounting a wrench,
A screw 53c for mounting the nut 52 is cut in the vicinity of the lower end. The nut 52 includes a sleeve 52a having a smaller diameter than the through hole 31a formed on the top surface of the caulking fitting 31 and a flange 52b having a larger diameter than the through hole 31a. The inner surface thereof corresponds to the screw 53c. It is threaded. In the above description, the multi-contact type contacts 33, 41, 42 such as a multi-ram band are shown in FIG.
As shown in (b), the conductive leaf spring 60 is provided in the width direction (A
(In the direction of the line), a large number of cuts 61 are formed to form a large number of bridges 62 connecting both edges, and these bridges 62 are twisted around their center line in the longitudinal direction as an axis to reduce the springiness in the thickness direction. This is a shape obtained by bending the applied material into a ring shape.

When assembling the cable head having the disconnection function configured as described above, first, the insulating bushing 1 is attached to the equipment case (15 in FIG. 5) of the electric equipment, and the tip of the insertion part 1a in the equipment case is mounted. Is connected to the high-voltage conductor on the device side. Next, after the sleeve 52a of the nut 52 is fitted into the through hole 31a of the caulking fitting 31, the caulking fitting 31 is put on the tip of the cable conductor 11a, and the plug 32 is press-fitted from the outside to press the tapered inner surface. The diameter of the slit-shaped conical portion 31b of the swaging metal fitting 31 is reduced, and the plug 32 and the cable conductor 11a are firmly connected via the swaging metal fitting 31. In this case, the flange 52b of the nut 52 is
The nut 52 is also connected to the cable conductor 11 a via the caulking fitting 31 by arranging the nut 52 below the top surface of the cable. The cable conductor 11a with the plug 32 attached in this manner is inserted into the plug insertion portion 30a of the shielding metal fitting 30, and is connected to the shielding metal fitting 30 by the multi-contact type contact 33. The stress cone 1 previously covered on the insulator 11b of the power cable 11
Numeral 4 is inserted into the tapered opening 1c, pressed by the stress cone pressing mechanism 14a, and pressed between the tapered surfaces to maintain the dielectric strength.

The connection of the connecting conductor plug 40 and the drop-out prevention mechanism 50 is performed through the upper tapered opening 1b.
In this case, the insulating plug 10 is removed, and the connecting conductor plug 40 is inserted into the plug insertion hole 1d. A fastening ring 51 is screwed into a screw portion 21c formed in an upper half portion of the plug insertion portion 21b of the conductor connection portion 21. As a result, the connection conductor plug 40 is pushed down to a predetermined position by the pressing portion 51b inserted into the concave portion thereof, and is connected to the conductor connection portion 21 via the multi-contact type contacts 41 and 42 mounted in advance.
Alternatively, they are pressed into contact with the plug insertion portions 21b and 30b of the shield fitting 30, and are electrically connected. Next, a retaining bolt 53 is inserted into a retaining bolt insertion hole formed at the center of the tightening ring 51 and the connecting conductor plug 40, and a lower end near a nut 52.
By screwing into this, the conductor connection part 21 and the cable conductor 11a side are mechanically connected to prevent the power cable from dropping out. Thereafter, the insulating plug 10 is attached to the upper tapered opening 1b, and the lid 9 is bolted to the end surface of the insulating bushing 1. As a result, the cable conductor 11a of the power cable 11 is electrically connected to the high-voltage conductor on the device side via the caulking fitting 31, the plug 32, the shielding fitting 30, the connection conductor plug 40, and the internal conductor 20, and is used for power transmission. used.

On the other hand, when the DC power application test of the power cable 11 is performed, the power cable 11 is disconnected from the device side in order to avoid the DC power application to the device side. Is removed from the insulating bushing 1, a tool is inserted through the upper tapered opening 1b, the retaining bolt 53 and the fastening ring 51 are removed by twisting, and the connection conductor plug 40 is further removed. After that, the same shape and the same size as the conductor plug 40 for connection (however, the contacts 41 and 42 are not attached,
Also, no grooves for mounting them are formed. ) Is inserted into the plug insertion hole 1d, and the fastening ring 51 and the retaining bolt 53 are attached again.
Is closed with an insulating plug 10. In this way, the shield metal 30 and the inner conductor 20 are cut off by the disconnection insulating plug.
By applying a DC voltage to a through a cable head at the other end (in the case of a device directly connected type, having a structure similar to that of FIG. 6), the power cable can be applied without applying a DC voltage to the device side. 11 DC withstand voltage tests can be performed. When connecting a test lead cable using the tapered opening 1b of the insulating bushing 1, a conductive plug with a multi-contact type contact is attached to the end of the cable conductor, and the conductive plug near the end of the cable insulating layer is attached. A test lead cable (not shown) having a pre-molded reinforcing insulating layer attached to the outer periphery is inserted through the tapered opening 1b, and the conductive plug is inserted into the plug insertion portion 30b of the shielding fitting 30, and the reinforcing insulating layer is inserted. May be pressed into the plug insertion hole 1d.

When power is to be applied to the equipment side, such as in an AC power application test, a conductive plug with a multi-contact type contact is attached to the end of the cable conductor and the outer periphery near the end of the cable insulating layer is attached. A test lead cable (not shown) having a pre-molded reinforcing insulating layer attached thereto is inserted through the tapered opening 1b, and the conductive plug is connected to the shielding fitting 3.
No. 0 may be inserted into the plug insertion portion 21a, and the reinforcing insulating layer may be pressed against the tapered opening 1b.

As described above, in the cable head with disconnection function of the present invention, the conductor connecting portion 21 of the internal conductor 20 and the shielding metal 30 are positioned in the insulating bushing 1 so that their axes are located on the same straight line. In the insulating bushing 1, a plug insertion hole 1d is formed between the conductor connection portion 21 and the shielding metal fitting 30, and tapered openings 1b and 1c opening toward the outer end of the axis are formed in a straight line. Therefore, the size of the insulating bushing 1 can be further reduced, and the weight and cost of the cable head can be reduced. In addition, as a result of forming the conductor connection portion 21, the shielding fitting 30, the plug insertion hole 1d, and the tapered openings 1b, 1c in a straight line, the connection is made using the tapered opening 1b to which the power cable 11 is not connected. Since the conductor plug 40 and the drop-out prevention mechanism 50 can be attached and detached, the degree of freedom of design increases, and the structure of the drop-out prevention mechanism 50 and the attachment / detachment work become easy.

[0016]

According to the present invention, it is possible to obtain a cable head having a disconnection function that is compact and can carry a large current and that does not accidentally come off even if a pulling force acts on the cable. it can.

[Brief description of the drawings]

FIG. 1 is a longitudinal sectional view of an embodiment of a cable head with a disconnection function of the present invention.

FIG. 2 is a plan view of the embodiment of FIG. 1 with an insulating plug removed.

FIG. 3 is an enlarged longitudinal sectional view showing the vicinity of a dropout prevention mechanism in the embodiment of FIG. 1;

FIG. 4 is an explanatory view illustrating a multi-contact type contact used in the present invention (FIG. 4 (b) is FIG. 4 (a)).
Sectional view along the line bb).

FIG. 5 is a longitudinal sectional view illustrating a conventional cable head with a disconnection function.

FIG. 6 is a longitudinal sectional view of a main part explaining a method of using the cable head of FIG. 5;

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Insulating bushing 2,20 ... Inner conductor 3,30 ... Shielding metal fitting 4,40 ... Connection conductor plug 5 ... Premold insulator 6,7 ... Shielding electrode 8 ... Spring 9 ... Lid DESCRIPTION OF SYMBOLS 10 ... Insulation stopper 11 ... Power cable 12 ... Cable terminal 14 ... Stress cone 15 ... Case side plate 16 ... Disconnection insulation stopper 17 ... Test lead cable 21 ... Conductor connection part 22 ... Conductor lead Part 31... Caulking fitting 32... Plug 33, 41, 42... Multi-contact type contact element 50... Pull-out prevention mechanism 51... Tightening ring 52... Nut 53. Spring 62 ... Bridge piece

Claims (3)

[Claims] 1. An insulating bushing comprising: an inner conductor having a conductor connection portion and a conductor lead-out portion; and a shielding metal fitting having a conductor connection portion for connecting a cable conductor, wherein the axes of the conductor connection portions are aligned with each other. , And insulated, forming a plug insertion hole in the insulating bushing between these conductor connecting portions, and tapering the insulating bushing on the outer end side of the axis of each conductor connecting portion. Forming an opening,
A plug fixedly inserted through a wedge fitting near the distal end of a cable conductor in a cable head in which a connection conductor plug is detachably inserted into the plug insertion hole, and both ends of the connection are conductively connected to the respective conductor connection portions. Between the conductor connection portion of the shielding fitting into which it is inserted, between the conductor connection portion on the other end side of the shielding fitting and the outer periphery near one end of the connection conductor plug inserted therein, and between the conductor connection portion of the internal conductor. A cable head with a disconnection function, wherein the portion and the outer periphery near the other end of the connecting conductor plug inserted therein are conductively connected by multi-contact contacts. 2. A cable head with a disconnection function according to claim 1, wherein a drop-out preventing mechanism is attached between the cable conductor and the conductor connection portion of the internal conductor. 3. A drop-off prevention mechanism comprising: a tightening ring attached to a conductor connecting portion of an inner conductor; a nut locked to a wedge at a tip of a cable conductor; and a connection between the nut and the tightening ring. The cable head with a disconnection function according to claim 2, wherein the cable head comprises a retaining bolt.