DE1538405A1 - Surge arresters - Google Patents

Description

PATENT LAWYERS ' DIPL-CHEM. DR. WERNER KOCH .. DR.-ING. RICHARD GLAWE DIPL-ING. KLAUS DELFS 1538405 HAMBURG-MÖNCHEN

2000 Hamburg-Großflottbelc · Waltzstrasse 12 · Call 892255 8000 some 22. LlebherrstraBs 20 Call 2265 48

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UNSERZEICHCHEN A 95 MÖNCHEN, den

MONKS

ELIiCTUICITY GB-M ^ kATIliG Kt.A '.

15, Newgate Street, London, E. Cl, ßn _G la-iid

Surge arresters.

It is known to use surge arresters to divert uiu dangerous overvoltages to earth that can occur on an electrical line due to lightning strikes or switching surges. Such Vorricntungeii consist essentially of a .aiiaaiil of spark gaps which are connected in series with non-linear resistors. Such an arrangement is connected between the line to be Schiitsäende and the earth and is surrounded by an insulated housing.

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If a number of series-connected spark cells are used, linear or non-linear resistors and / or capacitors can be used to influence the voltage distribution between the spark cells. The housing must contain the full, an de ii 'über er s pam am. Ss-bleiter lying Spam-un ^ standixalteii. FUi: άΰciisijaünun _tJ sieitun _b en several such pressures created in series can be used.

Such overspans are used to l '/ ec, .Sels ti'omkkreis, especially liraf tilbertragun ^ sleittui ^ eij. to scU'itaen. The not linear i / idex'stands are so bescuaffeii that their effective understanding diminishes, when the hinuurcii flowing stream becomes larger. jjanex does not get bigger even by an ijUtzeinsc-la ^ iiiit Currents an excessive voltage at this bridge generated, .lach der

whom, i only delivered from the system to scTiutzeadu ifecuselstroni (also called "Fol_, estroni"; der only stroiu flowing through the surge line the resistance of the non-linear increases. Resistances on, so that at the spark gaps a quenching occurs at oaer shortly before reaching the current strength ü. This process is wildly referred to as "self-extinguishing" (re-seal). The ability to self-extinguish is essential for the safe operation of the surge arrester;

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if an arrester were to remain conductive for even a second or two, the entire energy developed in the housing of the arrester would be sufficient to cause an explosion. It is therefore important to avoid a deterioration in the atmosphere inside the housing and also unintentional discharges at the spark gaps, since both can lead to failure of the surge arrester. It has been found, according to the invention, that a fundamental cause of discharges which can lead to such deterioration is the contamination of the outer surface of the spam arrester. The contamination creates particular difficulties in the case of high voltage lines where a number of surge arrester units are connected in series, since contamination of the outer insulating housing distorts the distribution of the noise across the various units of the arrangement. In practice, it is not feasible to compensate for the voltage distribution across the various units in a multi-part arrangement by means of lderst: 'indices that are each connected in parallel to one unit, as this would lead to an excessive loss of strength . More generally speaking, a capacitive coupling with the internal switching elements of the surge arrester can result from electrical discharges between different parts of the contaminated surface and, due to the distortion of the internal voltage distribution on the spark gaps, cause a flashover at operating voltage.

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In areas where there is a risk of pollution ordered, since the use of surge arresters is limited in practice to the protection of Lines, with intermediate distribution voltages. Surge arresters However, because of these pollution problems, in general not for high-voltage lines of more than 33 kV used. Such an impurity for example by industrial companies or near the coast by the salinity of the atmosphere caused. I've been on the army coast recently with natural contamination attempts with different Construction of surge arresters *! dui ^ chführ / b, none of which are under operating voltage for more than a year the pr-air conditions withstood.

The invention provides an improved form of a Surge arrester facing these difficulties can be reduced or switched off.

According to 15rf, an overvoltage arrester consists of an insulating housing, in which spark gaps and non-linear resistors are arranged, and a high-resistance shielding arranged inside the housing, which surrounds the arrangement consisting of spark gaps and non-linear resistors and from this is shunted . The overvoltage

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The voltage lying on the arrester is also due to the Shielding, which must have such a high resistance, that the power loss is kept within permissible limits. This shielding doesn't just help to stabilize the voltage applied to the arrangement, especially if there are several surge arrester units can be connected in series, but it also offers protection against contamination stray tensions on the outer surface of the housing, which generated by electrical discharges between different points on the outer surface, by coupling into the interior of the arrangement.

The high-resistance shield can consist of a resistance coating exist on the inner surface of the housing. However, the high-value resistor is expediently formed by a cylindrical insulating body, for example a porcelain cylinder, which is inside of the housing is arranged and the arrangement consisting of spark gaps and non-linear resistors surrounds, wherein the cylindrical body extends from one end of the housing to the other and on the outer and / or inner surface a resistance coating, for example a semiconducting glaze or ceramic coating. tion, has. This coating is similar to that of spark gaps and non-linear resistors existing arrangement connected in parallel. So that's because of that

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The voltage present in the surge arrester is also applied to the Topping;,! which as a result of the entire on the surge arrester must withstand lying tension. The cylindrical one However, the body is located inside the housing and thus in a closed and controllable manner The atmosphere. This avoids the difficulties that arise from being semiconducting Glazes or ceramic J3e layers in a contaminated The atmosphere is easily susceptible to corrosion and damage from discharge. Appropriately the diameter of the housing is made much larger than previously usual in order to accommodate the capacity between the surface of the housing and the shield or shields provided inside.

Furthermore, according to the invention, an outer casing be provided which surrounds the housing and consists of insulating material. This envelope can, for example made of porcelain, a fiberglass material impregnated with synthetic resin, or a PLASTIC such as Made of polyethylene. Since they have no mechanical stress has to wear, it can be relatively thin. she

is preferably ribbed or corrugated to increase the surface. This covering increases the distance between a possibly contaminated surface © ταιά

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the internal shielding by the surge arrester, so that a coupling of stray voltages with the internal electrical conduction path is further reduced will.

The insulating casing or the casing surrounding the casing, if one is provided, may have a peelable water-repellent casing. A peelable cover consists of a mixture of a copolymer, a microicrystalline axis and Eq. This "coating sc ^v heided during a long 2eit oil from, whereby the outer surface is kept water-repellent and no adhesion between the solid support surface and the tib.erzug held canoe. The 01, which is located between the solid support surface and the coating prevents the penetration of moisture. ¥ ¥ If such oversug is heavily contaminated, it can easily be removed and replaced with a new coating.

Instead of avoiding such a peelable cover, For example, the housing may be a hollow insulator with a number of oil baths provided on its outer surface that they «extend around the insulator. These Oil baths can be in one known per se for oil bath insulators Way to be trained. Preferably are on

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Robots or insulating bells suitable for the isolator (sheds) trained to direct the oil baths before To protect against rain or oil loss in strong winds. In a preferred embodiment, sf orin the housing for the surge arrester is made of porcelain and has a number of insulating globes, which take the form of annular protrusions all around the Geuäus extend. The oil baths are formed by suitable design of the tops of the insulating bells (sheds), by means of further annular projections between the insulating bells or by upwardly and inwardly directed projections at the ends of the insulating bells. The used Ul is expediently a transformer oil and results in a * water-repellent surface, which maintains a high electrical resistance, even if the housing is heavily contaminated. Other electrically insulating liquids can be used provided that they are water repellent and lighter than water.

In the following, embodiments "of the invention are explained in more detail with reference to the accompanying drawings. Figures 1 to h show partially schematic longitudinal sections through one embodiment of a surge arrester.

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As can be seen from each of the figures, the circuit of the voltage diverter consists of an arrangement Io of non-linear resistors connected in series 11 and spark gaps 12. between two metal end plates 13 »Ι ** · The device is between one to protective line, for example a power transmission line, and the earth switched. The spark gaps 12 become conductive when the voltage applied to the arrangement Io exceeds a specified value, that of depends on the setting of the spark gaps. The non-linear resistors 11 are such that you effective resistance decreases as the current flowing through it increases. Therefore a through. lightning strike caused very high current Ice ine cause excessive voltage on the resistors 11, after a temporary overvoltage increases the resistance of the non-linear resistances again, so that the spark gaps , 12 can go out.

In the embodiment shown in FIG. the arrangement Io is arranged in an insulating cylindrical housing 15, which usually consists of porcelain. This housing 15 has bell-shaped projections l6 on its cylindrical outer surface. At its ends it is closed by the aforementioned metallic end plates 13, lk. The plates 13, lk are in the one shown

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Embodiment attached to outer metal plates 18, which are screwed with foetal rings I9, which in turn are cemented to the outer surface of the housing 15. The inner surface of the housing 15 has a ¥ resistance covering 21, the sicli over the entire inner surface of the housing and is electrically connected by contacts 22 to the end plates 13, I ^. If the housing 15 is made of porcelain, the resistance coating is expediently a semiconducting one Glaze or ceramic coating. This resistance coating forms a shield, which to the arrangement consisting of spark gaps and resistors is parallel. You must have a sufficiently high resistance to the heat development within permissible limits to keep. In the event of contamination of the outer surface, this resistance cut-off reduces the Coupling of electrical discharges between parts of the outer surface with the spark gap arrangement via the shield. The shield also helps to stabilize the voltage applied to the arrangement at, especially if several surge arresters in Are connected in series, as is conveniently the case with a high-voltage line.

'Fig. 2 shows a modification of the embodiment of Fig. 1. Corresponding parts are with

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same Bezugszeicheu called, and the following wex-the only differently formed iierkmale mentioned "Ee-i of Ausfüliraa _b sForm of Fi ^. 2, a resistance lining is not intended on the Xrui-en side of the housing: but an inner cylindrical body 25 made of insulating material is provided in the interior of the housing, which in the embodiment shown has a Viders'tandsLelag 26 on its inner surface. Ber üelak 26 is durcu ilontaiite 2'7 init dexi j ^ ndplatten 13r I ^ electrical verbuuaeü. Such iiiaerstandsbelag ¹ may instead desseix or additionally, the inner surface of the body 25 au provided.

The body 25 can consist of porcelain and in this case the resistance coating, as in the embodiment of FIG. 1, expediently consists of a semiconducting glaze or ceramic coating. In the embodiment according to FIG. 2, however, it is easily possible to use a different material for the body 25 and the covering 26, since it is not a load-bearing structural element. Since the body 25 is entirely within the housing, it can be kept in a controllable atmosphere. Similarly, the lining 21 is ναΐΐ Fig «1 completely retained within the housing and can in a controlled atmosphere

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BATH

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will. This avoids the difficulties which are generally contaminated with semiconducting glazes or ceramic coatings Atmospheres occur.

Conversely, the inner body 25 can also be a load-bearing structural element and consist, for example, of porcelain or glass fiber material impregnated with synthetic resin, in which case the outer housing 15 can be a relatively thin casing. Such a cover can also be made of porcelain or synthetic resin-reinforced fiberglass material and is preferably ribbed or corrugated in order to increase the length of the surface. This covering increases the distance between a possibly contaminated surface and the shield, whereby any coupling of stray voltages into the interior of the arrangement is further reduced.

Fig. 3 shows a further embodiment of the invention. According to FIG. 3, the outer housing 3o is stranded on its inner surface with a resistance coating 31, which corresponds to the shielding 21 of FIG. On the outer surface, however, the housing 3o has a removable water-repellent coating, which is formed from a mixture of a mixed polymer, microcrystalline wax and oil, which for a long time

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for example, for several years, oil separates. This separated or exuded oil holds a water-repellent outer surface upright. The i / l between the surfaces of the cover 31 and the case 3o prevents the penetration of moisture and causes no adhesion between the coating and the support surface takes place. The coating 31 must be at regular intervals, for example every two -Years to be removed because of pollution. Because of this, the outer surface of the housing is different trained as at the in j? x £. 1 and 2 shown embodiment sfοrm. The surfaces here are generally conical with gentle Abruiidungen, the conical Bottoms of the bell-shaped ribs are flatter than the tops for attachment and removal to facilitate the coating.

Fig., H shows a further embodiment of the invention. Here the outer housing is a porcelain cylinder with bell-shaped ribs 41 which are designed on their upper side (with the exception of the topmost) so that they form annular oil baths k2 . The oil results in a water-repellent surface that maintains a high electrical resistance even when the housing is heavily soiled. The bell-shaped fins 4l are designed so that 3ie

BATH ORIGINAL

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Protect the oil baths from direct rainfall and from oil loss in strong winds. The inner surface of the Grahaus 4o has a resistance layer which is electrically connected to the end plates IJ, Ik. This LeIa ^, 4 3 and -as well as the BeIa ^ ₁ 25 of Fi &. 2 and the Ijelag 31 from jTi &. 3 act in the same way as the "Jelag 21 of L ^ ig. 1, in order to stabilize the tension lying on a junction of overpaixnuiigsableiterii and also an ilopplun ^ in the interior of every overpaniiun ^ sabluiters ^r £ \ x veriiiiideru-.

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Claims (11)

P a t e Ii t a χι s ρ r ü c Ii e 1.1 Surge arrester with a cylindrical housing in which at least one spark gap and at least one non-linear resistor are arranged, as a result, -, geke η η ζ eich u et, that inside the housing there is at least one high-ear shielding in front of the spark gap and non-linear resistances ordering arrangement and is connected in love with it. 2. Surge arrester according to claim 1, characterized g ^e 1 ^£ en η ζ eic Ii n. Et, daiä the iiochohmifee shielding consists of a cylindrical insulating body arranged in the iauiorn of the housing, which consists of funicen lines and non-linear resistors surrounding the arrangement surrounding the cylindrical insulating body extends from one end of the housing .to the other and has a resistor coating on one or both sides, which is connected in parallel to the arrangement consisting of spark gaps and non-linear resistors. BATHROOM - 15 - / 909 8377 067 5 3. Surge arrester according to claim 2, characterized gekenszeic.Iine t that the insulating cylindrical body is a porcelain cylinder. 4. Surge arrester according to claim 1, characterized geke η ία ζ eich ii et, because ^ V the high-resistance shielding consists of a v, ^r resistance coating on the inner surface of the G-eiiäuses. 5. Surge arrester according to claim 3 or 4, thereby g .e Ic e η η draws, that the cons » Stand flooring a semiconducting glaze or ceramic j. e layering is. 6. Surge arrester after one of the. Expectations 1 to 5 j characterized in that the housing with a removable, water-repellent überzug- versene.n is. 7. Surge arrester according to one of claims 1 to 5 j thereby ge Ic e η η ζ ei without t that an outer casing surrounding the ü-enäuse is provided, which consists of insulating material. 8. Surge arrester according to claim 7 » thereby g e k e η η ζ § i c h η e t that the outer Sheath is ribbed or corrugated. ■ * ■ - 16 - —-._ 909837/0 6 75 9. Surge arrester according to claim 7 or 8, as a result, ei.c h η e t, that the outer Covered with a removable, water-repellent cover is provided. 10. Surge arrester nacii one of the claims 1 to 5> characterized in that the Housing is a hollow insulator, on the outer surface of which a number of oil baths are provided which extend around the housing. 11. Surge arrester according to claim Io, characterized ge ke η η ζ eich η et that the housing has a number of insulating bells (sneds) which extend in the form of annular projections around the housing, and that the Ülbäder are formed by suitable design of the tops of the insulating bells, by means of further annular projections between the insulating bells, or by upwardly and inwardly directed projections on the edges of the insulating bells .; 6AD ORIGINAt - 17 V 90983770675 Blank page