JPH05137229A - Cable joint for direct connection with machine - Google Patents

Abstract

PURPOSE:To suppress thermal influence of machine body onto a cable by choking an auxiliary cable joint by means of an insulation plug made of high thermally conductive material mounting heat dissipating means such as fins. CONSTITUTION:An auxiliary cable joint 18 has a tapered hole 19 opening upward communicated with a conductor insertion hole 3a at the large diameter part 3 of a connecting conductor 2. A stopper 50 made of high thermally conductive material, e.g. copper, having a wedge part to be fitted tightly to the insertion hole 3a is screwed into the tapered hole 19 and then an insulation plug 51 made of high thermally conductive material having profile to be fitted tightly to the stopper 50 and the tapered hole 19 is fitted therein. Consequently, even when the temperature of refrigerant in an electric machine 41 is high, heat to be transmitted on the connecting conductor 2 from the electric machine can efficiently be dissipated to the outside through the stopper 50 made of high thermally conductive material, the insulation plug 51, and a finned metal 52. According to the invention, temperature of a CV cable 6 can be suppressed below the allowable temperature of insulation layer 6c.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a structure of a device direct connection type cable connecting portion which is attached to an electric device such as a transformer.

[0002]

2. Description of the Related Art In recent years, in response to an increase in the demand for electric power in urban areas, power equipment is often installed in urban areas. Especially when it is installed in a building or an underground mall, downsizing of electric equipment is a top priority as well as non-combustibility, safety and environmental harmony. For this reason, for example, a structure in which a gas-insulated transformer and a gas-insulated switch are interconnected by a gas-insulated busbar, which is designed to be compact by enclosing SF6 gas that is incombustible and excellent in insulating property, is generally adopted. ing. However, since the transformer and switch are often transported separately and assembled at the site, in such a configuration, it is necessary to disassemble and assemble the gas-insulated busbar at the site, and the insulating gas is A troublesome gas treatment for enclosing is required.

Therefore, in many cases, a device direct connection type cable connecting portion is attached to each device in advance, and the devices are connected by using a crosslinked polyethylene insulated vinyl cable (CV cable). ing.

An example of such a device direct connection type cable connection portion is shown in FIG. FIG. 4 is a sectional view of the connecting portion. In the figure, the bushing 1 is made of, for example, an epoxy resin, and has a connection conductor 2 embedded therein. The bushing 1 has a protrusion 1A and is L-shaped, and is attached to a case 41a of an electric device described later so as to penetrate the case 41a to insulate the internal connection conductor 2 from the case 41a. ing. A disc-shaped connecting portion 2A protruding from the resin insulating portion of the bushing 1 is formed below the connecting conductor 2 located in the case 41a of the electric device. Connected. A large diameter portion 3 is formed on the upper portion of the connection conductor 2 located outside the case 41a of the electric device, and the large diameter portion 3 is provided with a conductor insertion hole 3a along the vertical direction. Further, the large-diameter portion 3 of the connection conductor 2 is provided with another large-diameter portion 4 which is orthogonal to the large-diameter portion 3 and is located in the protruding portion 1A of the bushing 1,
The large diameter portion 4 is also provided with a conductor insertion hole 4a.

A cable connecting portion 5 is formed on the protruding portion 1A of the bushing 1. A CV cable 6, which is an external cable for device connection, is connected to the connecting portion 5, and the sheath layer is removed at the end of the CV cable 6, and the shielding layer 6a, the outer semiconductive layer 6b, the insulating layer 6c and The cable conductor 6d is exposed. Cable conductor 6
d is inserted into the conductor insertion hole 4a in the large diameter portion of the connection conductor 2 and is electrically connected to the large diameter portion 4 of the connection conductor 2.
That is, the wedge member 7 is pushed into the conductor insertion hole 4a on the cable conductor 6d through the fastening metal fitting 8, and the fastening metal fitting 8 is screwed into the thread groove provided on the inner peripheral surface of the conductor insertion hole 4a. Since the fastening metal fitting 8 is screwed in and the wedge member 7 is pushed into the conductor insertion hole 4a, the cable conductor 6d and the large-diameter portion 4 of the connection conductor 2 are electrically connected via the wedge member 7. Connected.

A mold stress cone 9 is fitted on the insulating layer 6c and the outer semiconductive layer 6b of the CV cable 6. The stress cone 9 is pressed by the pressing metal fitting 10 to form the tapered hole 1 of the protruding portion 1A of the bushing 1.
It is pressed against B. One end of a plurality of shafts 11 is screwed into and fixed to the push fitting 10.
Is movably inserted into the washer 13 via the tightening spring 12. The washer 13 is a cable protection fitting 14
It is locked to the inner peripheral side step. Therefore, since the pressing metal member 10 is pressed by the elastic force of the tightening spring 12,
As described above, the stress cone 9 is pressed against the tapered hole 1B.

The flange portion 14a of the cable protection fitting 14
Is attached to the end surface of the protruding portion 1A of the bushing 1 by the embedded nut 15
It is also fixed via a bolt 16 screwed into this nut 15. A waterproof tape 17 is wound around the small diameter portion of the cable protection fitting 14 so as to straddle the sheath layer of the CV cable 6.

An auxiliary cable connecting portion 18 is provided on the upper portion of the bushing 1. The auxiliary cable connecting portion 18 has a tapered hole 19 which opens upward and communicates with the conductor insertion hole 3a in the large diameter portion 3 of the connecting conductor 2.
A cylindrical stopper 20 that is in contact with the upper end surface of the large diameter portion 3 and an insulating plug 21 located above the stopper 20 are fitted into the tapered hole 19. Insulation plug 21 is E
It is made of P (ethylene propylene) rubber or the like, and the metal fitting 22 is embedded in the upper part. Lower ends of a plurality of shafts 23 are screwed into the metal fitting 22, and an upper portion of the shaft 23 is inserted into a washer 25 via a pressing spring 24. Since the washer 25 is locked to the step portion on the inner peripheral side of the protective cap 26, the insulating plug 21 is pushed into the tapered hole 19 by the elastic force of the pressing spring 24. The flange portion of the protective cap 26 is fixed to the upper end of the bushing 1 via an embedded nut 27 and a bolt 28 screwed into the nut 27.

The cable connecting portion 40 having such a structure is
As shown in FIG. 5, it is directly attached to an electric device 41 such as a gas-insulated transformer or a gas-insulated switch. That is, as shown in FIG. 4, the small diameter portion 1C of the lower portion of the bushing 1 is inserted into the through hole provided in the case 41a of the electric device 41, and the fixing metal fitting 29 is attached to the step portion 1D of the lower portion of the bushing 1. Is hermetically fixed by an O-ring through the embedded nut 30 and the bolt 31 screwed into the nut, and the fixing metal fitting 29 is attached to the upper surface of the case 41a by O.
The ring 41 is airtightly contacted via a ring, and is fixed to the case 41a by the holding metal fitting 32 and the fixing bolt 33. Further, the lower connecting portion 2A of the connection conductor 2 is electrically connected to the internal circuit of the electric device 41 via a connection bar (not shown) or the like. A semiconductive coating material is applied to the peripheral surface of the bushing 1.

With such a connecting portion, even if each device is transported separately and connected at the site, there is no need for gas treatment, and both cable terminals are treated beforehand. As a result, the on-site work can be greatly reduced and the reliability can be improved. Further, when performing a power-charging test of the equipment, the insulating plug 21 is removed from the auxiliary cable connecting portion 18, and the power-charging cable 42 is connected to the connecting portion 18, whereby the power-charging device 44 ends in the air. A test voltage can be applied to the internal circuit of the electric device 41 via the section 43.

[0011]

However, in the case of the above-mentioned structure, the CV cable 6 directly connected to the device 41 is used.
Are more susceptible to the heat of the device. Therefore, when it is attached to a device 41 such as a transformer that generates a large amount of heat, the temperature of the insulating layer 6c made of cross-linked polyethylene is controlled so that its allowable temperature is 90 ° C. or less (in the case of gas insulation, the temperature of the refrigerant is gas). It is necessary to design the temperature lower.

On the other hand, as mentioned above, there is an increasing demand for miniaturization of equipment, and when the miniaturization is attempted by raising the heat-resistant grade, the above restrictions are becoming a bottleneck. In other words, it is necessary to take measures such as pulling out the cable connection part from the lower part of the device with low temperature, or partially lowering the internal temperature by using the cable connection part as a separate room. It is an obstacle to rationalization.

The present invention has been made in order to solve the above-mentioned problems, and it is a small device direct connection type cable connection portion having a structure capable of connecting a power supply cable or the like, but to a cable directly connected to the device. It is an object of the present invention to provide a device direct connection type cable connection part capable of suppressing the influence of heat from the device body.

[0014]

In order to achieve the above object, the equipment direct connection type cable connection portion of the present invention is provided with a bushing which is fixed to the case of an electric equipment and insulates a connection conductor arranged inside. The bushing has a connecting conductor, a connecting portion connected to an internal circuit of an electric device inside the case, a cable connecting portion connected to an external cable outside the case, and other external portions. In a device direct connection type cable connecting portion formed with an auxiliary cable connecting portion connected to the cable, the auxiliary cable connecting portion is made of a high heat conductive material to which a heat radiating means such as fins is attached. It is characterized in that it is closed using an insulating plug.

[0015]

According to this structure, the heat from the connecting conductor is effectively transferred to the outside by the heat radiating means such as fins attached to the insulating plug through the insulating plug made of the high thermal conductive material of the auxiliary cable connecting portion. As it is dissipated, the heat effect on the cable insulation layer made of cross-linked polyethylene with low heat resistance is greatly reduced. Further, by removing the heat dissipating means such as the insulating plug and the fin and connecting the cable for charging, voltage can be easily applied to the internal circuit of the electric device.

[0016]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings. FIG. 1 is a sectional view of a device direct connection type cable connection portion according to the present invention. In this figure, the structure other than the auxiliary cable connecting portion is the same as that already described with reference to FIGS. 4 and 5, and is therefore omitted. Hereinafter, the structure of the auxiliary cable connecting portion will be mainly described for the different parts.

On the upper portion of the bushing 1, an auxiliary cable connecting portion 18 similar to the conventional one is provided. The auxiliary cable connection portion 18 is opened upward and communicates with the conductor insertion hole 3a in the large diameter portion 3 of the connection conductor 2 by a taper hole 19.
have. Unlike the conventional cylindrical stopper, a stopper 50 made of a high heat-conducting material such as copper having a wedge-shaped portion, which is almost in close contact with the insertion hole 3a, is screwed into the tapered hole 19, and then the stopper is formed. An insulating plug 51 made of an insulative and highly heat-conductive material is fitted into the tape 50 and the tapered hole 19. As a material of the insulating plug 51, for example, alumina (heat conductivity: about 30 W / m ° C.)
Alternatively, boron nitride (thermal conductivity: about 70 W / m ° C.) or the like can be used. However, since these materials have a small elastic modulus, it is desirable to form a thin layer of EP (ethylene propylene) rubber or the like on the surface in order to facilitate adhesion. Further, it is desirable to apply heat conductive grease to the contact surface of the stopper 50 with the connecting conductor 2 and the contact surface of the stopper 50 with the insulating plug 51.

A metal fitting 52 with a fin having a predetermined surface area is embedded in the upper portion of the insulating plug 51. The lower ends of a plurality of shafts 23 are screwed into the metal fittings 52, and the upper part of the shafts 23 are fitted with washers 55 through the pressing springs 24.
Has been inserted into. The washer 55 is locked to the step portion on the inner peripheral side of the protective cap 56, so that the insulating plug 51 is pushed into the tapered hole 19 by the elastic force of the pressing spring 24. The flange portion of the protective cap 56 is fixed to the upper end of the bushing 1 via an embedded nut 29 and a bolt 28 screwed into the nut 29. The attachment and use of the cable connecting portion 40 having such a configuration to the device is the same as that shown in FIG.

When such a cable connecting portion 40 is attached to a device such as a transformer that generates a large amount of heat, even if the refrigerant temperature inside the electric device 41 (gas temperature in the case of gas insulation) is high, the Device 41 to connection conductor 2
The heat transmitted through the above can be efficiently dissipated to the outside through the stopper 50, the insulating plug 51, and the fin-equipped metal fitting 52 which are made of the above-mentioned high thermal conductive material. Therefore, by selecting a fin having a desired size, it becomes possible to suppress the temperature of the CV cable 6 to be 90 ° C. or lower which is the allowable temperature of the insulating layer 6c portion made of particularly severe cross-linked polyethylene.

Here, as the heat transfer path from the electric device 41, a resin insulating layer of the bushing 1 and the like can be cited in addition to the connecting conductor 2. The resin insulating layer is a connecting conductor made of a highly heat conductive material such as copper. Since it is made of a material such as epoxy resin having a thermal conductivity much smaller than that of 2, its effect can be said to be small.

FIG. 3 shows an internal temperature distribution (analysis example) of a cable connecting portion having a conventional structure when an electric current of about 200 A is applied at an ambient temperature of 40 ° C. and a gas temperature inside the device of 110 ° C. As is apparent from this temperature distribution diagram, in the case of the conventional configuration, the insulating layer 6c of the crosslinked polyethylene of the CV cable 6 has a portion where the allowable temperature exceeds 90 ° C.

On the other hand, FIG. 2 shows an internal temperature distribution (analysis example) in the case of the embodiment of the present invention under the same conditions. The thermal conductivity of the insulating plug 21 is 60 W / m ° C. As is apparent from this figure, the temperature of the insulating layer 6c portion of the CV cable 6 can be reduced by about 10 ° C. Therefore, it is possible to take out a greater energizing ability or raise the internal temperature of the device. ..

When each device is transported separately and connected at the site, there is no need for gas treatment, and the CV cable 6 can be preliminarily processed at the end to greatly reduce the work on site. , It is possible to improve reliability, and when conducting a power supply test of equipment, by removing the insulating plug 51 from the auxiliary cable connection part 18 and connecting the power supply cable to this connection part 18, The test voltage can be applied from the device to the internal circuit of the electric device 41 via the air terminal, as in the conventional case.

In the above, the case where the metal fitting 52 with fins is used has been described, but by equipping the metal fitting 52 with another heat radiating means, for example, a heat pipe, the same or more effects can be obtained. Further, it goes without saying that the same effect is exerted also on electric devices other than the gas-insulated device.

[0025]

As described above, according to the present invention, a compact device direct connection type cable connecting portion having a structure capable of connecting a power supply cable or the like to a cable directly connected to the device is provided. Since the heat effect can be suppressed to a small level, for example, when increasing the heat resistance grade to reduce the size, pull out the cable connection part from the lower part of the equipment with low temperature, or use the cable connection part as a separate room to partially increase the internal temperature. Therefore, it is possible to provide an excellent device direct connection type cable connection part which can reduce the size of the device or rationalize the connection with other devices as a result.

[Brief description of drawings]

FIG. 1 is a sectional view showing an example of a device direct connection type cable connection portion according to the present invention.

FIG. 2 is a temperature distribution diagram of a device direct connection type cable connection portion according to the present invention.

FIG. 3 is a temperature distribution diagram of a conventional device direct connection type cable connection part.

FIG. 4 is a cross-sectional view showing an example of a conventional device direct connection type cable connection portion.

FIG. 5 is a schematic view showing a usage state of a device direct connection type cable connection portion.

[Explanation of symbols]

Reference numeral 1 is a bushing, 1A is a protruding portion, 1B is a tapered hole, and 1C.
Is a small diameter portion, 1D is a stepped portion, 2 is a connecting conductor, 2A is a disc-shaped connecting portion, 3 is a large diameter portion, 3a is a conductor insertion hole, 4 is another large diameter portion, 4a is another conductor insertion hole, 5 Is the cable connection part, 6
Is a CV cable for device connection, 18 ... Auxiliary cable connection part, 40 ... Cable connection part, 41 is an electric device, 41a is a case, 42 is a power supply cable, 43 is an air termination part, 4
Reference numeral 4 is a power supply device, 50 is a stopper, 51 is an insulating plug, and 52 is a metal fitting with fins.

Claims (1)

[Claims] 1. A bushing which is fixed to a case of an electric device and insulates a connection conductor disposed inside, and which is connected to an internal circuit of the electric device inside the case to the connection conductor of the bushing. Cable directly connected to the equipment, and a cable connection portion connected to an external cable outside the case and an auxiliary cable connection portion connected to another external cable. At the connecting portion, the auxiliary cable
A cable connecting portion directly connected to a device, characterized in that the bull connecting portion is closed by an insulating plug made of a high heat conductive material having a heat radiating means such as fins attached thereto.