JPS6328532Y2 - - Google Patents

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to an improvement of an insulated conductor structure for incorporation into electrical equipment.

[Conventional technology]

BACKGROUND ART Conventionally, an insulated conductor in which a solid insulator is placed around the conductor to maintain a predetermined withstand voltage has been employed for a power distribution bus bar that is incorporated into an electrical device.

By the way, in electrical equipment used at a high voltage of about 6 kV, the insulated conductor is affected by a strong electric field, and if left as is, there are problems such as a noticeable drop in withstand voltage and shortened life due to irregularities in the electric field.

Therefore, the surface of a solid insulator that electrically insulates the conductor is closely coated with a semiconductive resistor to prevent such electric field irregularities.

[The problem that the idea attempts to solve]

However, the above-mentioned semiconductive coating layer is made of rubber or plastic material mixed with carbon to have a volume resistivity of 10 ⁵ Ω-cm, and its electrical resistance value is high, so it is not used. Even if the conductor is grounded, if an insulation breakdown accident occurs due to damage to the solid insulator covering the conductor, the resulting ground fault current will not easily flow to the ground, and the semiconducting layer will be exposed to electrical heat. generates heat, ignites the insulators, and even causes a phase-to-phase short circuit between the insulated conductors installed in parallel to form each phase, increasing the internal pressure of the equipment casing that houses and seals the insulated conductors, creating a risk of explosion. It also had a sexuality.

Particularly in power distribution systems where a large number of devices are installed, this type of electrical equipment is often installed near sidewalks, so such explosions are a problem that can threaten human life, and improvements have been desired.

In view of the problems of the prior art described above, the present invention aims to provide an insulated conductor structure for incorporating into electrical equipment, which can improve the safety of electrical equipment using an insulated conductor having an external semiconducting layer. be.

[Means to solve the problem]

To achieve the above object, the insulated conductor structure of the present invention consists of a conductor with a terminal for connection to an in-device cable, an insulator covered around the conductor with the terminal exposed, and In an insulated conductor for incorporation into electrical equipment, which is formed by arranging a plurality of phase-forming insulated conductors in parallel and having an external semiconductive layer provided on the circumference, a metal plate is sandwiched between adjacent phase-forming insulated conductors. The outer semiconducting layers of the insulated conductors adjacent to the same metal plate are electrically connected to each other.

〔Example〕

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be further described below with reference to the accompanying drawings showing embodiments of the present invention.

FIG. 7 shows an example of a 6 kV class high voltage electrical equipment called a high voltage cabinet, in which each terminal of a main cable 10, a branch cable 11, and a feed cable 12 is inserted into the equipment casing from below the equipment casing C. An insulated conductor 1 with a terminal is connected between each of the cables 10, 11, 12 in a detachable manner via a movable electrode 13, and by attaching and detaching the movable electrode 13, each cable 10, 11, Opening/closing operations are performed for 12 hours.

As is clear from FIGS. 1, 2, and 5, the insulated conductor 1 includes a flat conductor 6 and a main cable 10, a branch cable 11, and a feed cable 12. A conductor is constituted by the three terminals 6a that are integrally connected, and an insulator 7 formed by molding resin such as rubber or plastic is formed around the terminals 6a, especially on the circumference of the plate-shaped conductor 6.
are integrally covered and given a predetermined insulation structure,
Furthermore, an external semiconductive layer 8 is formed on the outer periphery of the insulator 7 by coating with a conductive resin such as rubber or plastic mixed with conductive powder such as carbon to cope with irregularities in the electric field.

The terminal 6a is exposed within the cylindrical portion 7a of the insulator 7 provided around the terminal 6a, and is adapted for plug-in connection with a terminal on the movable electrode side that can be connected to and removed from the cable.

One of the insulated conductors configured as described above connects one phase of the cable, and in the case of a three-phase three-wire line cable as shown in the figure, three insulated conductors 1, 2 and 3 are arranged side by side with a contact plate 5 interposed therebetween, and are bound together by a fixing member 4 such as a combination of a contact plate and a bolt/nut, thereby forming a predetermined set of insulated conductors.

In addition, each insulated conductor 1, 2,
The electrodes 3 are arranged so as to be offset in the longitudinal direction of the conductor 6 and lined up on the same line, so that they can be stored compactly in the casing C.

Now, in the insulated conductor structure constructed in this way, conventionally, the insulated conductors 1, which form each phase,
The two and three external semiconducting layers 8 were each grounded by short-circuiting them to the device casing C.

Therefore, the external semiconducting layer 8 has a high specific resistance value, and there is a limit to the reduction in the resistance value.

Therefore, in the event that a dielectric breakdown accident occurs due to damage to some of the insulators 7, the ground fault current will flow through the external semiconducting layer 8 and the equipment casing C, which is grounded, to the earth. However, in this case, the external semiconducting layer 8, which serves as the flow path for the ground fault current, has a high resistance and therefore has a small current carrying capacity, which delays the operation of the protective relay attached in connection with ground fault detection. There was a risk that an arc would occur and destroy the insulators of other phases, leading to a transition from a ground fault to a short circuit between phases.

In view of such circumstances, the present invention provides an outer semiconducting layer 8
Focusing on the purpose of reducing the burden of ground fault current on adjacent insulated conductors 1 and 2, as shown in FIGS. A metal plate 9 is interposed between the metal plates 2 and 3, and each of the external semiconductive layers 8 of each insulated conductor is brought into electrical contact with the metal plate 9.

Therefore, if the metal plate 9 is short-circuited using a connecting means such as a metal bolt or nut used when assembling the metal plate 9 into the device casing C, the outer semiconducting layer 8 of each insulated conductor is automatically grounded. state.

According to the insulated conductor structure for incorporation into electrical equipment of the present invention constructed in this way, if the insulator 7 of a part of the insulated conductor is damaged and dielectric breakdown occurs, the resulting Since the ground fault current quickly flows from the external semiconducting layer 8 to the metal plate 9 that contacts and conducts, and then flows to the ground through the equipment casing C, the protective relay operates quickly, causing a ground fault that spreads to a phase-to-phase short circuit accident. Since power can be cut off before the accident occurs, damage caused by an accident can be kept to a minimum.

As shown in FIG. 6, the metal plate 9 is made wider so that it is sandwiched between the metal plates 9 and protrudes further from the parallel insulated conductors 1, 2, and 3, thereby creating a heat dissipation fin. Since it can be used as a conductor, it activates the dissipation of heat generated by energization of each insulated conductor, especially the central insulated conductor 2 where heat is easily trapped.
It is also possible to increase the current carrying capacity by improving the cooling effect in this way.

[Effect of idea]

As explained above, according to the insulated conductor structure for incorporation into electrical equipment of the present invention, insulation is applied on the conductor attached with a terminal for openable/closable connection with the in-equipment cable. Since the metal plate is provided so as to be electrically conductive to the external semiconducting layer that prevents electric field irregularities through the body, the grounding resistance that was previously caused by only the external semiconducting layer being grounded has been reduced. By eliminating the problem of high ground resistance and making the combined grounding resistance sufficiently low, the ground fault current can easily flow to the ground, preventing serious accidents such as phase-to-phase short circuits and minimizing damage caused by accidents. We can prevent this from happening and make it safer, etc.
Its practical value is enormous.

[Brief explanation of drawings]

1 and 2 are top and front explanatory views showing an example of a conventional insulated conductor structure for assembling in electrical equipment, and FIGS. 3 and 4 show an example of an insulated conductor structure for assembling in electrical equipment according to the present invention. FIG. 5 is a cross-sectional view showing details of the structure of the terminal portion of the insulated conductor, and FIG. 6 is a modified example of the insulated conductor structure for incorporation into electrical equipment according to the present invention. FIG. 7 is a front view showing how the insulated conductor structure is incorporated into equipment. 1, 2, 3: Insulated conductor, 4: Fixing metal fittings, 5: Plate, 6: Plate conductor, 6a: Terminal, 7: Insulator,
8: External semiconductive layer, 9: Metal plate, 10: Trunk side cable, 11: Branch side cable, 12: Sending side cable, 13: Movable electrode, C: Equipment casing.

Claims (1)

[Scope of utility model registration request] A conductor with a connection terminal attached to the in-device lead-in cable, an insulator covered on the circumference of the conductor with the terminal exposed, and an external semiconductive layer provided on the circumference. In an insulated conductor for built-in electrical equipment, which is made by arranging multiple phase-forming insulated conductors in parallel, a metal plate is inserted between adjacent phase-forming insulated conductors, and the adjacent insulated conductors are connected to the same metal plate. An insulated conductor structure for incorporation into electrical equipment, characterized in that each of the external semiconducting layers is electrically conductive.