JP3337904B2 - Device direct connection type terminal - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION A power distribution system is generally composed of equipment, cables, and accessories. When a cable is connected to equipment, accessories are used to secure electrical and mechanical performance of a connection portion. That is, a device directly connected to the device is required. The present invention relates to a device direct connection type terminal for connecting the above-mentioned cable to a device, and more particularly to a device direct connection type terminal capable of ensuring a required insulation performance and being compact.

[0002]

2. Description of the Related Art In general, a terminal directly connected to a device is formed by fitting a cable conductor or a terminal with a molded product of EP rubber or silicon rubber to a device bushing centered on a conductor molded of epoxy or the like, and forming an interface by rubber elasticity. Many maintain pressure and waterproof performance and insulation performance. In this case, the outer diameter of the device bushing made of epoxy or the like is made slightly larger than the outer diameter of the rubber molded product, and a fitting diameter difference is generated at the time of fitting, so that the interface pressure is secured. There are three types of terminals: straight type, L type, and T type. The terminal body consists of three layers: an inner semiconductive layer, an insulating layer, and an outer semiconductive layer. The cable shielding layer side forms a stress cone. The charging section is sealed. As the conductor connection structure, a blade terminal clamping type, a tulip type, and a multipoint contact type are used.

FIG. 4 is a diagram showing an example of a conventional T-type terminal directly connected to equipment. In the figure, 100 is a terminal body, 101
Is a cable, 102 is an adapter used according to the conductor size of the cable, 103 is a terminal, 104 is an insulation plug, 1
05 is a protective cap, 106 is a device bushing.
Then, in the device direct connection type terminal portion, this connection is made for connection between the device bushing and the insulator of the terminal body. Also,
In the terminal body 100, 111 is an external semiconductive layer, 11
2 is an insulating layer formed of EP rubber or silicon rubber, 11
Reference numeral 3 denotes an internal semiconductive layer. The terminal main body 100 includes an insulating tube 107 having a fitting surface with the device bushing 106 and the insulating plug 104, and a terminal 103 to which a cable conductor is connected.
The terminal insertion section 108 for inserting the

The assembling of the T-type terminal shown in FIG. 1 is performed, for example, as follows. (1) The terminal 103 is compression-connected to the cable 101 and inserted into the terminal insertion section 108 of the terminal body 100. (2) Connect the insulating cylinder 107 of the terminal body 100 to the device bushing 1
06, and the terminal 103 and the conductor on the device side are bolted. (3) The insulating plug 104 is fitted into the insulating tube 107 and screwed. In the T-type terminal with the above structure,
An insulating cylinder 107 of the terminal body 100 formed in a tapered shape;
The insulating plug 104 is pressed in the axial direction of the device bushing 106, and the pressure at the interfaces A and B is secured by the elasticity of the rubber of the insulator 112 of the terminal body 100.

[0005]

A device directly connected to a device by connecting a cable to a device naturally has a structure that can be used for a long time in a natural environment and has a structure that does not hinder connection work on site. Required. In addition, in recent years, there has been a demand for more compact and multifunctional devices than ever before. In recent years, in particular, S
F6 gas has been sealed in for compactness, and accordingly, terminals directly connected to equipment have also been required to be more compact.

[0006] As shown in FIG. 4, the terminal directly connected to the device is generally connected to a device bushing made of epoxy or the like.
A molded product such as P-rubber is fitted to ensure waterproofness and insulation performance at the interface pressure due to rubber elasticity. Therefore, when the fitting diameter difference is large, the interfacial pressure increases, and the creeping fracture stress can be increased. The dielectric breakdown at the interface is started when the highest electric field on the interface reaches the discharge starting voltage. The discharge starting voltage is a function of the surface pressure, and it is said that the higher the surface pressure, the higher the discharge starting voltage. Then, when the surface pressure between the surface of the device bushing and the inner surface of the insulating layer of the terminal body was determined along the axial direction of the device bushing, the result was as shown in FIG. Naturally, as shown in the figure, the portion where the thickness of the insulating layer is thickest near the tip of the device bushing has a high surface pressure. From this,
If the potential distribution structure is such that the equipotential lines are concentrated on the portion where the surface pressure is high as much as possible, desired insulation performance can be ensured even if the device directly connected to the device is made compact.

An object of the present invention is to concentrate necessary equipotential lines on the portion where the surface pressure is high, so that a necessary interfacial withstand voltage can be ensured, and it is easy to use a compact device such as a gas insulating device. It is an object of the present invention to provide a device direct connection type terminal that can be applied to a device.

[0008]

Therefore, when an electric field analysis was performed at the interface, the neck portion of the T-shaped terminal was constricted, so that the lines of electric force were applied to the bushing tip side (the insulator body of the terminal body). Pressure side). That is, when the terminal is made compact and the height L is reduced, the electric lines of force gather on the side of the terminal body where the body pressure is thin, and an electric field more than expected from the interface pressure is applied. When the “constriction” is provided, even if the height L of the terminal is reduced, the electric flux lines are distributed over the entire design interface length, and the electric flux lines in the thin portion of the terminal body are formed. Can be made relatively small.

According to the present invention, based on the above concept, an insulating cylinder formed of an insulator made of an elastic member and having a fitting surface with an equipment bushing and an insulating plug, and a terminal insertion portion for inserting a terminal connected to a cable conductor. Comprising a terminal body arranged in a direction in which the insertion direction of the device bushing and the insertion direction of the terminal are orthogonal to each other, fitting the fitting surface of the insulating cylinder into the device bushing, and While being inserted into the terminal insertion portion and connected to the conductor of the device bushing, the insulating plug is fitted to the fitting surface of the insulating tube, and the insulating tube and the insulating plug are pressed in the axial direction of the device bushing to form the insulating tube. Due to the elasticity, in a device directly connected type terminal that secures an interface pressure between the insulating cylinder and the insulator of the device bushing and the insulating plug, a high electric field is generated on the tip side of the device bushing. The, the terminal insertion portion side of the connecting portion near the insulating cylinder and the terminal insertion portion is provided with a constricted portion of the insulator,
Make the thickness of the insulation layer in the constricted area the same as the insulation thickness in other parts.
It was done.

[0010]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 is a diagram showing the configuration of a device-directly connected T-type terminal according to an embodiment of the present invention. FIG. 1 shows an example of a device directly-connected 6.6 kV T-type terminal. In FIG.
1 is a terminal body, 2 is a bushing on the device side made of epoxy resin or the like, 3 is a cable, 4 is a conductor 3 of the cable 3
The terminal 5a is crimped and the insulating plug 5 is made of epoxy resin or the like. The terminal body 1 includes an inner semiconductive layer 1a, an insulating layer 1b formed of an elastic material such as EP rubber, silicon rubber, and the like, and an outer semiconductive layer 1c. It comprises an insulating tube 8 having a surface and a terminal insertion portion 9 for inserting the terminal 4 to which the cable conductor 3a is connected. In the vicinity of the connection portion between the insulating tube 8 and the terminal insertion portion 9 of the terminal main body 1, a "constriction 7" according to the present invention is provided as shown in FIG. The thickness of the insulating layer in the portion where the constriction 7 is provided is the same as the other portions.

A stress cone is formed on the cable shielding layer side of the terminal main body 1. After the cable 3 is inserted, taping is performed with a semiconductive tape 3b and an insulating tape 3c. In addition, the grounding wire 3 d extends from the shielding layer of the cable 3.
Is pulled out. The terminal 4 is connected to the conductor 2a of the equipment bushing 2 by a bolt 6 having a screw hole at the top via a washer 6a. The insulating plug 5 has a bolt 5 that engages with a screw hole provided at the top of the bolt 6.
b is embedded. Then, the bolt 5b is screwed into a screw hole provided at the top of the bolt 6, and the insulating plug 5 is attached.

At the top of the insulating plug 5, a conductor 5a to which a terminal for power detection is attached is embedded. An electric detection cap 5e is detachably attached to the conductor 5a, and the electric detection cap 5e is a grounding member 5 made of conductive rubber or the like.
c, it is attached to the external semiconductive layer 1c of the terminal body 1. A capacitance is formed between the conductor 5a and the conductor 5d formed integrally with the bolt 5b, and when the power detection cap 5b is removed, a voltage is generated on the conductor 5a during power application. .

The above device T-terminal directly connected is assembled as follows. After the cable conductor 3a is compression-connected to the terminal 4 and inserted into the terminal insertion portion 9 of the terminal body 1, the cable 3 and the end of the terminal body 1 are subjected to taping with a semiconductive tape 3b and an insulating tape 3c. The insulating tube 8 of the main body 1 is fitted to the device bushing 2, and the terminal 4 is bolted to the conductor 2 a of the device bushing 2 with the bolt 6. Then
The insulating plug 5 is fitted into the insulating tube 8, and the bolt 5 b embedded in the insulating plug 5 is engaged with a screw hole provided on the top of the bolt 6, and the entire insulating plug 5 is turned to remove the bolt 5 b. The screwed insulating plug 5 is attached to a screw hole provided at the top of the bolt 6.

FIGS. 2 and 3 show the results of the electric field analysis of the conventional example and the embodiment of the present invention. FIG. 2 (a) shows the results of the electric field analysis of the terminal shown in FIG. (B) shows an electric field analysis result when no constriction is provided in the terminal of the embodiment of the present invention, and FIG. 3 shows an electric field analysis result when the above “constriction” is provided in the terminal of the embodiment of the present invention. Is shown. In the figure, 2 is a device bushing, 8
Is an insulating cylinder, and A is an interface between the insulator of the terminal body 1 and the device bushing 2. In the case of the conventional T-type terminal shown in FIG. 4 which is not downsized, the height L of the terminal can be sufficiently ensured. Therefore, as shown in FIG. It is distributed over the entire interface length, and the designed interface length and the effective interface length can be made substantially equal. On the other hand, as shown in FIG. 2B, when the height L of the terminal is reduced to L ′ as a result of reducing the size of the terminal, the lines of electric force gather on the part of the terminal main body 1 where the body pressure is thinner, and the design is reduced. The effective interface length becomes shorter than the interface length.

On the other hand, when the “constriction” is provided as in the present invention, even if the height L of the terminal is reduced, as shown in FIG.
The electric flux lines are distributed over the entire design interface length, the design interface length and the effective interface length can be made approximately equal, and the density of the electric flux lines in the thin part of the terminal body can be compared. Can be made smaller. When the ratio of surface pressure to stress (= stress / surface pressure) shown in FIG. 5 is obtained, when [constriction] is provided as described above, the above [stress / surface pressure] is substantially reduced. While it was possible to keep it constant, it was found that when no “constriction” was provided, the above “stress / surface pressure” increased on the thinner side of the terminal body (the base side of the bushing). That is, when the height L of the terminal is reduced without providing the “constriction”, an electric field more than expected from the interface pressure is applied. Table 1 shows the results of assembling the T-type terminal of this example and examining the insulation performance.

[0016]

[Table 1]

That is, when the “constriction” is not provided, the dielectric breakdown occurs at the interface between the device bushing 2 (epoxy) and the insulating cylinder (rubber) of the terminal body 1 at 45 kV in the document 1,
In Reference 2, the same dielectric breakdown occurred at 55 kV. On the other hand, when the "constriction" is provided,
In document 1, the insulation cylinder of the terminal body 1 caused a breakthrough at 75 kV, and in document 2, a similar breakdown occurred at 85 kV. As is clear from the above test results, in the case of "constriction", the breakdown value is sufficiently high, and the fracture location is a penetration failure of the insulating cylinder rubber that is not related to the interface, whereas the "constriction" In the case where there is no such material, it is broken at the interface between the epoxy of the device bushing 2 and the rubber of the insulating cylinder 8, and the effect of concentrating the electric field on the side where the surface pressure is high clearly appears due to "constriction".

[0018]

As described above, according to the present invention, the terminal insertion portion side near the connection portion between the insulating cylinder and the terminal insertion portion is so arranged that the side having the higher interface pressure at the tip side of the device bushing has a high electric field. Since the constricted portion is provided, the lines of electric force can be distributed over the entire design interface length, and the density of the lines of electric force in the thin portion of the terminal body can be relatively reduced. For this reason, it has become possible to reduce the size of the terminal directly connected to the device while ensuring the necessary insulation performance.

[Brief description of the drawings]

FIG. 1 is a diagram showing a configuration of a T-type terminal according to one embodiment of the present invention.

FIG. 2 is a diagram illustrating an electric field analysis result when no “constriction” is provided.

FIG. 3 is a diagram showing an electric field analysis result of the example of the present invention.

FIG. 4 is a diagram showing a conventional device directly connected T-type terminal.

FIG. 5 is a view showing a surface pressure between an equipment bushing and an insulating cylinder.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Terminal main body 1a Internal semiconductive layer 1b Insulating layer 1c External semiconductive layer 2 Equipment bushing 2a conductor 3 Cable 3a Cable conductor 3b Semiconductive tape 3c Insulating tape 3d Ground wire 4 Terminal 5 Insulating plug 5a Conductor 5b Bolt 5c Grounding member 5d Capacitance between conductors 5e Power detection cap 6 Screw hole bolt 6a Washer 7 Constriction 8 Insulation cylinder 9 Terminal insertion part

Continuation of the front page (56) References JP-A-2-10173 (JP, A) JP-A-63-21765 (JP, A) JP-A-62-47562 (JP, A) JP-A-4-141968 (JP) JP-A-62-133685 (JP, A) JP-A-2-83628 (JP, U) (58) Fields investigated (Int. Cl. ⁷ , DB name) H01R 4/70 H01R 13/533 H01F 27/04

Claims (1)

(57) [Claims] An apparatus comprising: an insulating cylinder formed of an insulator made of an elastic member and having a fitting surface for fitting a device bushing and an insulating plug; and a terminal insertion portion for inserting a terminal connected to a cable conductor. A terminal body disposed in a direction in which a bushing insertion direction and a terminal insertion direction are orthogonal to each other, wherein the fitting surface of the insulating cylinder is fitted to a device bushing,
The terminal is inserted into the terminal insertion portion and connected to the conductor of the device bushing, the insulating plug is fitted to the fitting surface of the insulating tube, and the insulating tube and the insulating plug are pressed in the axial direction of the device bushing to press the terminal. In the device directly connected type terminal which secures the interface pressure between the insulating tube and the insulator of the device bushing and the insulating plug by the elasticity of the insulating tube, the insulating tube is so arranged that the tip side of the device bushing has a high electric field. Provide a constricted part of the insulator on the side of the terminal insertion part near the connection part of the terminal insertion part and the thickness of the insulating layer of the constricted part.
Characterized by having the same insulation thickness as that of the other parts .