JPH0381251B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a high voltage insulator, particularly a suspended insulator.

Polymer rod type suspension insulators, like other rod type insulators, have extremely non-linear voltage distribution along the longitudinal direction, compared to insulators with interference metal members interposed in the middle, such as conventional ceramic suspension insulators. It has the disadvantage of being large. This non-linear voltage distribution gives excessive voltage stress to the vicinity of the metal joint of the insulator, especially to the voltage-applying end portion. This stress increases as the voltage at which the insulator is used increases. In extreme cases, air breakdown occurs in this high stress area, causing corona noise and radio interference.

In the case of polymer insulators, this phenomenon appears at system voltages of 138kV or higher. At a system voltage of around 138 kV, even standard end fittings must sufficiently maintain the radio interference voltage (radio interference) value below 100 μv at the nominal line-to-ground voltage value (or at a voltage value 10% or more higher than the nominal value). I can do it.

However, if the grid voltage exceeds 161kV, excessive radio interference will occur, making the standard design unusable. Therefore, a method for easily and effectively reducing this voltage stress and preventing visible corona noise and excessive radio interference has been desired.

This reduction in voltage stress can be achieved using known corona rings, but these rings are expensive and large in size, and at voltages of around 161kV, overhead wires are relatively close to the ground. Moreover, the appearance is also unsightly.

Dielectric breakdown in air is caused by the large electric field density (voltage gradient) at the interface between the end joint and the insulator. At this interface, the organic insulator, metal end fittings, and surrounding air all exist within a high electric field density. There is no problem with the voltage level and the associated electric field density up to a certain level before dielectric breakdown of the air occurs. If the steep voltage gradient can be reduced, even higher grid voltages can avoid the problems of corona noise and radio interference.

Therefore, by using semiconducting polymers at high voltage metal end fittings, this voltage gradient can be reduced and radio interference and corona generation can be prevented or controlled to an acceptable range. . Furthermore, it has been found that prevention of radio interference and an increase in the leakage distance for all insulators, especially (desirable for insulators used in contaminated conditions), can be expected by using a special form of roof member. Served. The special roof element (which may be referred to as a "corona shield") can be identical in appearance to other roof elements on the insulator and can be aesthetically pleasing. This corona shield is inexpensive and can be easily manufactured using conventional molding techniques.

In the use of semiconducting polymers, the corona shield need not be in intimate electrical contact with the end fitting over the entire area, but may only be in partial contact. This is because even this partial contact can eliminate the voltage difference between the spaces. If semiconductive rubber is not used near the end fitting, if there is an air gap between the insulating material and the end fitting,
Air will be present at the interface between the organic insulator and the metal, making corona noise and radio interference more likely to occur. If such a corona occurs, it will damage or destroy the organic insulator. Since the corona shield is formed separately from the metal end joint, and the end joint is not uniformly smooth, the above-mentioned harmful void exists at the interface between the corona shield and the end joint, which wraps around the end joint. More likely.

Conventionally, attempts have been made to fill the void at the interface with grease as a shield for enclosing the insulator end joint. However, the problem remains that the grease oozes out or gets absorbed into the organic insulating material over time.

The present invention has been made in view of the above circumstances.

The present invention will be described below with reference to illustrated embodiments.

In FIG. 1, a conventional suspension insulator 1 has a central member 10 made of resin-bonded glass fibers, and metal joints 11 are fixed to the upper and lower ends of the central member 10, respectively. These metal joints 11 are the central member 1
0 can be fixed in various ways, but generally, as shown in the figure, the conical epoxy resin molded article 1
It is fixed through 2. The central member 10 is housed within a sheath 14 which is sealingly secured to a lip 15 of the end fitting 11. Connected to this sheath 14 is a series of roof members 16 of substantially identical shape. Suspended insulators with such a structure are known, but since there is a high electric field density near the end joint under high voltage,
Radio interference occurs when used above the grid voltage.

Figure 2 shows a semiconducting skin on an insulator.
This is a polymer insulator that embodies the principle of That is, an insulating sheath 17 is formed over the entire length of the glass fiber rod 18, and a roof member 19 having a collar 20 is disposed thereon. The structure of the roof member 19 integrally provided with the collar 20 is such that each roof member 19 provided with the collar 20 is in contact with the roof member 19 similarly provided with the collar 20. Furthermore, the second
As can be seen, each collar 20 fits into a groove formed by the next adjacent roof member 19. Roof member 19 closest to metal end fitting 11
(provided with a collar 20 as described above) extends towards this end fitting 11. In FIG. 2, this contact is made through sleeve 22. In this way, one continuous roof member (including the collar) completely covers the sheath 17. The material of the sheath 17 and the roof member 19 (including the collar 20) is not particularly limited as long as it is suitable for outdoor use as a high-voltage insulating material; for example, ethylene propylene rubber is used. These roof members 19 (including collar 20) must be properly adhered to sheath 17. The same applies to the adhesion of the sheath 17 to the rod 18. This is to prevent interfacial current flow and moisture accumulation. Such bonding can be accomplished by the use of adhesives or by vulcanizing the unvulcanized sheath 17 to a previously vulcanized roof member 19 (including collar 20) and rod 18.

If the roof member 19 (including the collar 20) is entirely made of insulators, no voltage stress dissipation effect will be found;
) and the contact sleeve 22 (closest to the end fitting) are semi-conductive, the large electrical stress will be spread over a large area and the corona strength will be significantly reduced. however,
The polymer insulator shown in FIG. 2 is susceptible to corona noise and radio damage because air is present at the interface between the organic insulator and the metal.

FIG. 3 shows an embodiment of the present invention, which does not require a completely empty space between the insulating elastomer and the end fitting. That is, by surrounding the cavity with equipotential surfaces, no partial discharge occurs within the cavity. By making a portion of the roof member 24 electrically conductive as contact elastomer material 23, it and the end fitting 11 are at the same potential, reducing radio interference when voltage is applied.

Tests of an insulator with a contact elastomer material 23 and a roof member 24 as shown in Figure 3 have shown that this polymer suspended insulator has a very low radio interference voltage (RIV) (less than 100 μV) even when used at grid voltages of 230 kV and above. This was possible, and no visible corona was observed. On the other hand, when similar tests were conducted on the conventional insulator shown in FIG. 1, very high radio interference voltage and visible corona were observed. The roof member 24 is significantly less expensive than conventional corona shield grading rings, and is smaller and less unsightly. The insulator provided with the roof member 24 according to the present invention is substantially the same in appearance as the insulator not improved according to the present invention, and provides a desirable aesthetic appearance. Additionally, the semiconducting corona shield of FIG. 3 can increase the leakage distance of the insulator and improve its performance under contaminated conditions.

Further discussion of the particular configuration of contact elastomeric material 23 and roof member 24 of FIG.
Preferably, erosion of the semiconductive elastomeric material 23 due to large surface leakage currents is prevented.
To this end, a semi-conductive elastomeric material 23 is disposed within a recess of a tracking- and erosion-resistant, non-conductive contact elastomeric member 24, covering substantially all surfaces of the elastomeric material 23 exposed to external and surface leakage currents. I'll do what I do. Roof member 24
This configuration of the elastomeric material 23 is highly resistant to erosion and can effectively solve radio interference and corona problems associated with high electric field densities at rubber-metal-air junctions.

FIG. 4 shows the portions associated with the contact elastomeric material 23 and roof member 24 of FIG. 3, which portions may be referred to as the "corona shield." The difference between this corona shield and a corona shield is that the corona shield does not have a protruding roof member. This Corona Shield serves the same purpose of avoiding radio interference and corona activity. This corona shield is used when the top end fitting requires such protection. If a corona shield is used at the top, it will turn upside down and collect rainwater.

[Brief explanation of drawings]

FIG. 1 is a cross-sectional view of a conventional polymer suspended insulator, FIG. 2 is a cross-sectional view of a polymer suspended insulator in which the semiconductor contact portion is not isolated from the external environment, and FIG. 3 is a cross-sectional view of a polymer suspended insulator according to the present invention. The cross-sectional view shown, FIG. 4, is a cross-sectional view of the elastomeric material of the semi-conducting electrode without the protruding roof member. 11... End joint (metallic joint), 18... Rod (insulating member), 19, 24... Roof member (non-conductive elastomer member), 23... Semiconductor contact portion (contact elastomer material).

Claims (1)

[Claims] 1. An insulating member 18 made of a non-conductive material, a high voltage metal joint 11 fixed to the insulating member 18 via an insulating sheath 17, and a plurality of non-conductive elastomers disposed on the insulating sheath 17 and the insulating member 18. A high-voltage insulator used in an outdoor environment at a voltage of 138 kV or higher, the elastomer member 24 of one of the base end portions of the elastomer members 19 being in contact with the high-voltage metal joint 11. A portion of the elastomeric member 24 at the proximal end is comprised of a semiconductor contact portion 23 which is directly supported against the high voltage metal joint 11 and which has an equipotential surface below. The elastomer member 24 at the proximal end is formed by directly molding onto the semiconductor contact portion 23, and is in contact with the high voltage metal joint 11 and the insulating sheath 17. An insulator characterized by covering the surface of the semiconductor contact portion 23 other than the area where the semiconductor contact portion 23 is exposed, thereby shielding the semiconductor contact portion 23 from the external environment.