JPS6031381Y2 - Cable end support - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a support part for a cable end part that is useful when a surge voltage generated between a lower metal fitting of a non-grounded cable end part and a grounding frame is discharged in a low voltage region.

When installing a single-core cable, only one end of the cable is sometimes grounded to eliminate loss due to circulating current flowing through the shielding layer of the cable.

By the way, in such a cable line with one end grounded, a surge voltage of about 15 KV is generated between the cable shielding layer and the ground when the load is turned on or off, and this surge voltage causes a discharge to occur at the end of the cable on the non-grounded side. may occur.

That is, as shown in FIG. 1, at the cable terminal end on the non-grounded side, a lower metal fitting 1 provided at the lower end of the sleeve covering the cable terminal section is connected to a bolt 4 and a nut through an insulating washer 2 and an insulating bushing 3. Since the lower metal fitting 1 is connected to the grounding frame 6 by the grounding frame 6, electric discharge occurs between the lower metal fitting 1 and the grounding frame 6.

However, this discharge phenomenon may damage the insulating washer 2, or in some cases, the bolt 8 that tightens and fixes the mantle.
Since discharge occurs between the ground frame 6 and the ground frame 6, there is a problem that the discharge position is not constant and causes anxiety to the operator.

Further, when no discharge occurs, a voltage of about 15 KV remains generated in the cable shielding layer, which is extremely dangerous.

Therefore, as shown in FIG. 2 in which the same parts as in FIG. A supporting part for a cable end part has been proposed in which a surge voltage is discharged between opposing electrodes 13 provided on the top surface of the cable.

By the way, in the supporting part of the cable terminal part, an insulating cap 14 is attached to the top of the bolt.

This insulating cap 14 is attached to prevent the intrusion of rainwater and adhesion of dust when the cable terminal end is used outdoors and to schedule the discharge phenomenon to the outside.

However, with this type of support, although it is possible to generate a spark discharge through the gap 14, if a corona discharge occurs at the top of the bolt or a spark discharge occurs at the gap 14,
Since the insulating cap is made of rubber or plastic material, it has the disadvantage of not being able to prevent noise radio waves caused by corona discharge, etc., and has low mechanical strength and is susceptible to external shocks.

In addition, in the figure, 9a and 9b are insertion holes, 10 is a flange, and 11
indicates a hanging piece.

The present invention was developed based on the above-mentioned circumstances, and aims to provide a support part for the cable end part that reduces noise during discharge and protects the area around the discharge part from external impact. be.

Hereinafter, the details of the present invention will be explained based on the drawings.

In FIG. 3, where the same parts as in FIGS. 1 and 2 are given the same numbers, a lower metal fitting 1 is fixed to the lower end of the sleeve that covers the end of a rubber or plastic insulated cable (not shown), and a lower metal fitting 1 is fixed to the outer edge of the sleeve. An insertion hole 9a is formed in.

An insertion hole 6b is formed at a predetermined location of the grounded pedestal 6, and a bolt 4' is inserted between this insertion hole and the insertion hole 9a of the lower metal fitting 1 from the pedestal side.

This bolt 4' is at the same potential as the ground frame 6,
Electrical insulation is maintained with respect to the lower metal fitting 1.

In order to insulate the lower metal fitting 1 from both the bolt 4' and the grounding frame 6, for example, a ring-shaped insulating washer 2 is disposed between the lower metal fitting 1 and the grounding frame 6, and an insulating washer having a flange 10 at the upper end is used. The sex cylinder 3' may be attached to the outer periphery of the port 4'.

Note that the insulating cylinder 3' may be formed of a cylinder and a ring-shaped insulating washer fixed to the upper end of the cylinder.

A ring-shaped discharge electrode 12' having a hanging ring 11' on the outer periphery is disposed on the insulating cylinder 3', and a ring-shaped discharge electrode 12' is disposed between the upper surface of the lower fitting 1 and the lower surface of the flange 10 so as to face the discharge electrode 12'. A washer-shaped counter electrode 13 is provided.

These electrodes 12' and 13 are for discharging a surge voltage between them, but they are not limited to the embodiment shown in FIG. Good too.

Note that the counter electrode 13 may not be provided if the upper surface of the lower metal fitting 1 is polished to facilitate discharge.

The discharge electrode 12' has a washer 15 provided thereon.
A shielding ring 14' made of a metal material or a semiconducting material is attached to the tip of the bolt, and this shielding ring protects the discharge electrode 12 and the counter electrode 13 from each other. The whole thing is covered.

The shielding ring 14' is shaped like an inverted bowl, and a mounting portion 17 is provided at the center of its inner surface to be engaged with the tip of the bolt 4'.

The attachment portion 17 is formed by fixing a cylindrical body or a nut or the like having a thread on the inner surface to the center of the inner surface of the shielding ring 14 .

Note that the attachment portion 17 is not limited to this, and for example, a cylindrical body may be fixed to the inner surface of the shielding ring, and the tip of the bolt may be fitted into this.

Reference numeral 18 denotes an insulating ring made of rubber or plastic material that is provided around the lower edge of the shielding ring 14'.When this ring is provided, the tip of this ring can be brought into contact with the upper surface of the lower fitting 1, thereby preventing rainwater from entering. This has the advantage of preventing the intrusion of dirt, dust, etc.

In the present invention, the bolt and nut constitute a fastener.

As mentioned above, in the present invention, a surge voltage is discharged between a discharge electrode held in contact with a bolt at ground potential and a counter electrode that is in contact with the upper surface of the lower metal fitting, and this discharge portion is covered with a shielding ring. Compared to the conventional cable end support, which covers the discharge part with an insulating cap made of rubber or plasticac material, the bolt 4'
When the corona discharge from the tip of the discharge electrode and the discharge electrode is suppressed, and the noise radio waves caused by the spark discharge at the discharge electrode are also shielded by the shielding ring, the noise can be greatly reduced, and when the shielding ring is made of a metal material. Because of its high mechanical strength, it has the advantage of being able to protect against external impacts.

[Brief explanation of the drawing]

FIGS. 1 and 2 are sectional views of main parts of a support part of a conventional cable end part, and FIG. 3 is a sectional view of main parts of a support part of a cable end part in the present invention. 1...Lower metal fitting, 4, 4'...Bolt, 5゜6...Nut, 9a. 9b...Through hole, 12゜2'...Discharge electrode, 13...Counter electrode, 14...Insulation cap, 14'...・Shielding ring, 17... Mounting part.

Claims (3)

[Scope of utility model registration request] (1) A lower metal fitting attached to the lower end of the sleeve that covers the cable terminal, and a grounding frame that supports this lower metal fitting;
A fastener that is inserted between the grounding metal fitting and the insertion hole formed in the lower metal fitting while maintaining electrical insulation to firmly connect the two; 1. A supporting part for a cable terminal end comprising a levered discharge electrode, wherein a shielding ring covering the discharge electrode is attached to the top of the fastener. (2) The support portion for the cable termination portion according to claim 1, wherein a mounting portion coupled to the top of the fastener is provided at the center of the inner surface of the shielding ring. (3) The support portion for the cable termination portion according to claim 1 or 2 of the utility model registration claim, wherein an insulating ring is provided at the lower circumferential portion of the shielding ring.