EP1603140A1 - Active component for an encapsulated surge arrester - Google Patents

Abstract

An encapsulated surge diverter has a varistor stack (3) between a high tension (4) and earth (5) electrode. A field control element (6) made of a polymeric matrix with a filler is mounted directly on the varistor stack (3). It has a dielectric value between 5 and 45 in an alternating field up to 100 Hz and a non-linear current-voltage characteristic. Independent claims are also included for the following: (1) A method of manufacturing the active part of a surge diverter that involves attaching the filed control element (6) to the varistor stack (3) or to the surrounding insulator; (2) An encapsulated surge diverter containing such an active part. The field control element can extend over the whole length of the varistor stack and can incorporate additional insulating layers. It is made by casting, injection molding or shrink-winding. The remainder of the capsule (1) is filled with a solid, liquid or gaseous insulator (13).

Description

TECHNICAL AREA

The invention is based on an active part for an encapsulated Surge arrester according to the preamble of claim 1. The invention also relates to a process for the preparation of such an active part and one of Voltage limiting in medium and high voltage networks serving encapsulated surge arrester containing the active part.

Such an active part is in the manufacture of the surge arrester in a Non-contact encapsulation used, which is generally made of metal consists of conductive, such as aluminum, an aluminum alloy or steel Plastic or made of insulating material, with an electrically conductive layer is covered. The active part has one with high voltage and one with earth potential connectable electrode and one or more varistor columns, which are arranged between the two electrodes.

The varistor column generally contains several stacked ones cylindrical varistors based on doped zinc oxide. At least between two of the varistors can also heat absorption or be arranged an extension of the column serving metal body. Are two or more varistor columns provided, so can between two of the varistors also an insulating body can be provided. The varistors of the different columns can then be connected in series.

The encapsulation is with an insulating material, which solid, liquid or gaseous can be filled. The encapsulation protects the arrester against contact reached. To keep the dimensions of the encapsulation low and around the To load individual varistors electrically evenly at the same time, takes the Encapsulation also connected to the high-voltage electrode element on which controls the operation of the arrester inside the enclosure acting electric field serves.

To manufacture the active part, a stack of varistors and two Terminal electrodes, one of which is the high voltage electrode, under Forming a varistor column or a portion of this column containing Mounting unit braced and subsequently the field control on the Mounting unit is attached. In the manufacture of the surge arrester are the thus created active part and the field control in the Encapsulation used,

STATE OF THE ART

Active parts of the type mentioned in the introduction are described in the patent documents EP 0 036 046 B1, EP 0 050 723 B1, EP 0 630 030 B1 and US 5,585,996 A listed below. These active parts are installed in surge arresters, which in each case have a metal enclosure filled with insulating gas, such as SF ₆ , or optionally with insulating oil, in which, depending on the level of the voltage to be limited, a varistor column or a plurality of varistor columns connected in series are arranged. In order to keep the dimensions of the enclosure small, each of these surge arresters between Varistorsäule resp. Varistorsäulen and Kapselungswand a pillar resp. arranged the columns annular surrounding field control. This field control element homogenizes the electrical field acting inside the housing during operation of the arrester, so that the varistors arranged in the varistor column or in the varistor columns are loaded more or less uniformly. The field control element can be formed by concentrically arranged to the column axis, electrically conductive capacitor pads, which are held in an insulating body (EP 0 036 046 B1), along the column axis arranged and spaced apart in the axial direction capacitor shields have (EP 0 050 723 B1) or may be formed by a shielded at high voltage potential shielding electrode having a spherically curved surface portion.

In a previously known from EP 1 083 579 A2 encapsulated surge arrester can the field control omitted, since by appropriate training of the Housing the uniformization of the electric field in the on High voltage potential located portion of the varistor column is achieved.

It is also known that stress control tasks can be solved by means of stress-controlling material, in particular a polymer-based composite and a suitably-formed filler embedded in the polymer. For this purpose, an article by R. Strümpler et al. "Smart Varistor Composites" Proceedings of the 8 ^th CIMTEC Ceramic Congress and Forum on Materials Symposium (1994) and US 6,124,549 A and EP 1 337 022 A1. The filler is in this case formed by Mikrovaristoren, which consist of small, substantially spherical zinc oxide particles. These particles are doped with various metal oxides such as Sb ₂ O ₃ , Bi ₂ O ₃ , Cr ₂ O ₃ and Co ₃ O ₄ and are sintered at temperatures between 900 ° C and 1300 ° C. Like a varistor, the sintered particles have nonlinear electric field strength dependent electrical properties. At low field strengths, the particles behave as an insulator, and as the field strength increases, the particles become more conductive. Because of these nonlinear electrical properties, the polymeric composite has good field control properties.

PRESENTATION OF THE INVENTION

The invention, as indicated in the claims, the object is based, an active part of the type mentioned for an encapsulated To provide surge arrester, which is simple and the Dimensions of encapsulation significantly reduced, and at the same time a procedure specify, with which this active part are easily and inexpensively manufactured can.

In the case of the active part according to the invention, the field control element is on the varistor column and contains one of a polymeric matrix and one in the matrix embedded filler composite formed when loaded with a alternating electric field of up to 100Hz a dielectric constant between 5 and 45 and / or has a non-linear current-voltage characteristic. That from the Compound-fabricated field control element has opposite one usually made of metal or an electrically conductive plastic Field control on a low conductivity. Therefore, that can Field control be brought very close to the varistor column. Accordingly, the active part has a low across the varistor column Diameter and so can the dimensions of the encapsulation as well as Isolators, which are intended to hold the active part can be reduced. The relatively high dielectric constant of the field control element and / or the non-linear Current-voltage characteristic also cause a homogenization of the electric field and thus prevent overloading of individual varistors Varistor. A particularly high surge voltage resistance, as in Type tests of surge arresters are required, the active part after the Invention on when the field control a non-linear current-voltage characteristic having.

An adequate field control for many applications is achieved when the filler is a material of high conductivity, in particular conductivity black, and / or high dielectric constant, e.g. a titanate, preferably barium titanate, contains and / or microvaristors.

Have excellent reproducibility of its electrical properties the active part or a surge arrester containing this active part after Invention, when at least a part of the filler contains microvaristors. This results from the fact that the electrical properties of the microvaristors, in particular based on doped and sintered zinc oxide, in Dependence on the chemical composition and the sintering conditions of the filler can be adjusted. Accordingly, so can the electrical properties of the field control element forming polymer Composite, in particular its field strength-dependent electrical Resistance, by choosing suitable microvaristors and choosing one appropriate concentration of the microvaristors in the polymer can be adjusted. There the electrical resistance is an intrinsic property of the microvaristors, and not - or only very slightly - the dispersion of the microvaristors in the Depending on the polymer matrix, this property of the microvaristors can therefore with great reproducibility can be set. The good reproducibility becomes This additionally increases that a filled with micro varistors polymer in the A higher compared to an unfilled polymer or to an insulating gas Has thermal conductivity. The higher thermal conductivity causes stronger Load the varistor column a better heat transfer away from the Varistor.

To solve difficult field control tasks, it is sufficient if the active part or a surge arrester according to the invention containing this active part Field control at least one with the high voltage electrode connected longitudinal portion which typically has a quarter of Total length of the varistor column is.

To cover the remaining sections of the varistor column with good accuracy To be able to control, the field control element can conveniently on the extend the entire length of the varistor column. Such a field control element has also manufacturing advantages, as it with one of the two electrodes the active part adjacent mold can be made very easy and Accordingly, the manufacturing cost of the active part reduced.

For reasons of saving space and a particularly high effectiveness of At least a portion of the field control may be on the field control The lateral surface of the varistor column rest. Local field inhomogeneities in the area the varistor column are effectively prevented.

In general, sufficiently good field control properties will be achieved achieved when the field control of a on the lateral surface of the Varistor column held insulating body is worn. Such a trained Active part has manufacturing advantages, as by pouring one easily handling filler-free polymer on the varistor column or on several optionally provided varistor columns a solid cylinder is achieved on the the field control, for example, by winding or spraying the filler and polymer-containing composite are applied in a simple manner can.

For certain field controls, a field control can be used which at least two by an electrically insulating layer from each other having separate field-controlling layers. These layers have an advantage different electrical properties and / or extend differently far over the length of the varistor column.

The thickness of the field control element transverse to the column axis is generally off manufacturing reasons over the length of the varistor column constant. to Solution of certain field control tasks, but it may be advantageous if the Thickness varies along the length of the varistor column. So it can be for example to Increasing the electrical conductivity at one end of the active column advantageous be there if there the area cross section of the field control element is higher and the Cross-sectional area decreases continuously over the length of the active part.

In the intended for the preparation of the inventive active part Procedures are a stack of varistors and two terminal electrodes below Forming a varistor column or a portion of this column containing Mounting unit clamped. Below is the field control at the Mounting unit attached by the field control on the varistor column or an insulator surrounding the varistor column is applied. Since that Application with advantage by casting or injection molding of the filled polymer or by shrinking or winding a carrying body holding the filled polymer done, the active part can be inexpensive and in one for mass production suitable methods are produced.

To a high dielectric strength of the inventive active part can reach after the onset of the Active part in the enclosure a remaining residual volume with solid, liquid and / or gaseous insulating material.

BRIEF DESCRIPTION OF THE DRAWINGS

Fig.1

eine Aufsicht auf einen axial geführten Schnitt durch einen Überspannungsableiter mit einer zylindersymmetrischen Kapselung und mit einem in der Kapselung angeordneten Aktivteil nach der Erfindung, enthaltend ein Feldsteuerelement, welches eine Hochspannungselektrode und einen an die Hochspannungselektrode anschliessenden Abschnitt einer Varistorsäule überdeckt,

Fig.2

eine Aufsicht entsprechend Fig.1 auf einen Überspannungsableiter, bei dem das Feldsteuerelement im Unterschied zur Ausführungsform nach Fig.1 die gesamte Varistorsäule und einen Teil einer auf Erdpotential befindlichen Elektrode überdeckt,

Fig.3

eine Aufsicht entsprechend Fig.1 auf einen Überspannungsableiter, bei dem das Feldsteuerelement im Unterschied zu den vorhergehenden Ausführungsformen auf einem die Varistorsäule umgebenden Isolierkörper angeordnet ist,

Fig.4

eine Aufsicht entsprechend Fig.1 auf einen Überspannungsableiter, bei dem im Unterschied zu den vorhergehenden Ausführungsformen die Dicke des Feldsteuerelements quer zur Achse der Varistorsäule ausgehend von der Hochspannungselektrode über die Säulenachse abnimmt,

Fig.5

eine Aufsicht entsprechend Fig.1 auf einen Überspannungsableiter, bei dem im Unterschied zu den vorhergehenden Ausführungsformen das Feldsteuerelement zwei durch eine isolierende Schicht voneinander getrennte feldsteuernde Schichten aufweist, welche sich unterschiedlich weit über die Länge der Varistorachse erstrecken, und

Fig.6

eine Aufsicht auf einen axial geführten Schnitt durch einen Überspannungsableiter mit einer zylindersymmetrischen Kapselung, mit einem in der Kapselung angeordneten Aktivteil nach der Erfindung mit zweialternativ mit drei Varistorsäulen - und mit einem Feldsteuerelement.

With reference to drawings, embodiments of the invention will be explained in more detail. Hereby shows:

Fig.1

a plan view of an axially guided section through a surge arrester with a cylindrically symmetric encapsulation and with an encapsulated active part according to the invention, comprising a field control element which covers a high voltage electrode and a subsequent to the high voltage electrode portion of a varistor column,

Fig.2

1 shows a plan view of a surge arrester, in which the field control element, in contrast to the embodiment according to FIG. 1, covers the entire varistor column and a part of an electrode located at ground potential,

Figure 3

1 shows a plan view of a surge arrester in which, in contrast to the preceding embodiments, the field control element is arranged on an insulating body surrounding the varistor column,

Figure 4

a plan view corresponding to Figure 1 on a surge arrester, in which, in contrast to the previous embodiments, the thickness of the field control element transversely to the axis of the varistor column decreases from the high voltage electrode on the column axis,

Figure 5

a plan view corresponding to Figure 1 on a surge arrester, in which, in contrast to the previous embodiments, the field control element comprises two separated by an insulating layer field-controlling layers which extend at different lengths over the length of the varistor, and

Figure 6

a plan view of an axially guided section through a surge arrester with a cylindrically symmetric encapsulation, with an arranged in the encapsulation active part according to the invention with two alternative with three varistor columns - and with a field control element.

WAYS FOR CARRYING OUT THE INVENTION

In all figures, like reference numerals refer to the same effect Parts. The surge arresters shown in Figures 1 to 5 have each one designed as an open pot cylindrically symmetric metal encapsulation 1, in which an active part 2 is arranged. The active part contains a varistor column 3, an electrode 4 which can be led to high voltage, which can be led to earth potential Electrode 5 and one between the varistor column 3 and the encapsulation. 1 arranged and with the high voltage electrode 4 electrically conductive connected element 6 for controlling a in operation of the arrester inside the Encapsulation 1 effective electric field.

The varistor column 3 contains a plurality of stacked solid cylindrical Varistor elements 7 made of nonlinear resistance material, approximately on the basis of Metal oxide, in particular of suitably doped ZnO. The varistor column 3 is mechanically stabilized by electrically insulating running loops 8, the forming a stable mounting unit with preload on the two Electrodes 4 and 5 (Figures 1 to 3 and 5) or on any two electrodes one of which is the high voltage electrode 4 and the other the groundable electrode 5 may be (Fig.4).

The high voltage electrode 4 is through a through the opening of the pot guided current conductor 9 arranged with a outside of the enclosure 1 Plug contact 10 electrically connected. The groundable electrode 5 is over a opening provided in the bottom of the pot with the aid of a relative to the Encapsulation 1 electrically insulated conductor 11 to an outside of the Encapsulation 1 arranged disposable power connector 12 out. An insulating body 13, based for example on the basis of a silicone, isolated the conductor 9 and the Active part 2 opposite the encapsulation 1.

The field control element 6 is held directly or indirectly on the varistor column. It contains one of a polymeric matrix and one embedded in the matrix Filler formed composite that under load with an electric Alternating field of up to 100Hz a dielectric constant between 5 and 45, preferably between 8 and 30, and / or a non-linear current-voltage characteristic having.

The polymeric matrix is made from a solid silicone based elastomer but may also be derived from any other elastomer, e.g. an EPDM or a butyl rubber. Other suitable for the polymeric matrix Polymers are thermoplastics, such as PE, PVC, PBT or EVA, duromers, for example based on epoxy or polyurethane, or thermoplastic elastomers. The Polymeric matrix may also consist of copolymers or mixtures of various Polymer components exist.

As a material for the embedded in the polymeric matrix filler Microvaristors used. Another suitable filler is conductivity black, which is to be introduced into the polymer in such a high concentration that the Dielectric constants of the resulting composite at 50 Hz at about 10 to 30 lie. Also suitable as a filler is a ceramic with a high dielectric constant, like barium titanate.

The microvaristors are formed of doped and sintered zinc oxide particles. Typical compositions, particle sizes and sintering conditions are the referred to at the beginning of the prior art. One with oxides of typically Bi, Co, Cr, Mn and Sb, and optionally other elements, such as Al, B, Fe, Ni, Si, doped ZnO granules were heated at temperatures between 900 ° C and sintered at 1300 ° C. The microvaristor powder forming on sintering became sieved to a desired particle size fraction of, for example, 100 μm. Optionally, metallic filler fillers can be mixed into this powder fraction and are sintered to the micro varistors. The sieved powder is z. B. on a mill in the polymeric matrix (eg., In a HTV silicone) incorporated. ever Depending on the type of elastomer, further additives (such as, for example, crosslinking aids, Stabilizers) are added. The volume fraction of the filler at Composite is typically between 20 and 45 percent.

The thus prepared composite was molded into the field control element 6 in FIG a conventional injection molding process on the Varistorsäule 3 or a Section thereof or on an insulating body 14 surrounding the varistor column (Fig.3) applied. If the silicone is liquid, then the silicone filler mixture be applied by direct casting. After networking the Composite can in a second process step designed as silicone Insulating material of the body 13 are injection-molded.

The field control element 6 made of the composite faces usually a metal or an electrically conductive plastic produced field control on a low conductivity. Therefore it can be very can be brought close to the Varistorsäule 6 and can accordingly after installation of the active part 2 in the enclosure 1, the dimensions of the enclosure and insulators provided for holding the active part 2 are reduced become. The relatively high dielectric constant of the field control element and / or the Non-linear current-voltage characteristic also cause when operating the arrester a uniformity of the electric field and prevent such a Overloading of individual varistors 7 of the varistor column 3. By the use of Ceramic microvaristors will increase the thermal conductivity of the composite Field control element 6 substantially increased compared to a filler-free polymer. It is therefore increasingly dissipated heat from the varistor column 2 to the outside. Accordingly, the individual varistors can be thermally stressed more become. A surge arrester having the active part according to the invention points to a surge arrester with a conventional built active part to a much higher surge voltage. Therefore Its dimensions can be reduced with comparable properties.

In the embodiment of Figure 1, the field control element 6 is optionally using an adhesion-promoting coating on the outer surface of the High voltage electrode 4 and a lateral surface of a with the High voltage electrode connected portion of the varistor column 3 attached. Characterized in that the field control element 6 over the with high voltage potential stretches acted areas of the active part 2, the electric field in Homogenized this electrically particularly stressed areas. The fact that the field control electrode is mounted on the varistor column is A space - saving design enables local field inhomogeneities in the field Area of Varistorsäule 3 effectively prevented and at the same time becomes a particularly good dissipation of heat generated in the varistor column 3 to the outside causes.

In the embodiment according to FIG. 2, this extends on the varistor column 3 applied field control element 6 from the high voltage electrode 4 via the entire varistor column 3 to the ground electrode 5. Therefore, is now above the entire varistor column homogenizes the electric field and so can all Varistors 7 of the varistor column are controlled with good accuracy. moreover can be equipped with such a field control active part be made very easy, as in the production of one of the two Electrodes 4 and 5 of the active part 2 fitting mold can be used.

In a surge arrester with an executed according to Figure 2 active part The withstand voltage was in accordance with the IEC regulations 60099-4 and 60071-1 tested and compared with the suitably tested dielectric strength of a appropriately designed arrester, which, however, no field control had. Both surge arresters were each rated 15 successive wave-shaped 1.2 / 50 high-voltage pulses with positive and loaded with 15 corresponding pulses of negative polarity. The shape of the Pulses are determined by a rise time of 1.2 μs to the pulse maximum and a decay time of 50 μs to half the pulse maximum. This showed it is that the arrester with the inventively designed active part with could be loaded at least 1.7 times higher high voltage than the Arrester without field control.

In the embodiment of Figure 3, the field control element 6 of the on Jacket surface of the varistor column held insulating 14 is supported. Such a thing trained active part 2 has manufacturing advantages, as by Pouring an easy-to-use filler-free polymer on the Varistorsäule 3 a full cylinder is reached, on the field control element. 6 for example, by winding or spraying the composite or by Shrinking a composite body holding the carrier in a simple manner can be applied.

The thickness of the field control element 6 transverse to the axis of the varistor column 3 is in general for manufacturing reasons over the length of the varistor column constant. To solve certain field control tasks, however, it is advantageous that the thickness of the field control element 6 varies over the length of the varistor column 3. So It may, for example, to increase the electrical conductivity of the with High voltage acted upon end (electrode 4) of the active column be advantageous if there the area cross section of the field control element 6 is higher and the Cross-sectional area continuously over a section or possibly over the entire Length of the active part 2 decreases. Such an embodiment of the active part is made 4 can be seen. It can also be seen from this figure that the varistor column 3 may consist of two assembly units 31 and 32, which each two Electrodes, an interposed stack of varistors 7 'and 7 "and loop-shaped clamping elements 8 'and 8 "respectively. The two electrodes are at the mounting unit 31, the high voltage electrode 4 and a Intermediate electrode 15 and the mounting unit 32, the intermediate electrode 15 and the groundable electrode 5. The intermediate electrode 15 may be separable, so that the two assembly units 31, 32 transported separately can be. For very long extended Varistorsäulen 3 are mounting units provided, which have as electrodes only intermediate electrodes.

In the embodiment illustrated in FIG. 5, a field control element 6 used, which two by an electrically insulating layer 61 from each other having separate field controlling layers 62 and 63. The layers 62 and 63 allow a very accurate field control and can be different have electrical properties and / or extend - as shown in the figure it can be seen - differently far over the length of the varistor column. 3

The exemplary embodiment according to FIG. 6 shows that the Active part 2 not only contains a varistor column, but also two varistor columns 3 ', 3 "or optionally also three (indicated by a behind the columns 3 ', 3" arranged varistor column 3 '' ') and may contain more varistor columns. There at This embodiment, the varistors 7 of both columns via power connector 16 in Series connected, these columns contain in addition to the varistors 7 and two the Column front end electrodes 17 ', 17 ", 17' '' also insulating pieces 18, which arranged the electrical potentials of adjacent in the columns Varistors 7 or a varistor 7 and an electrode 17 '' 'separate. It is obvious of the aforementioned electrodes, the electrode 17 'with the High voltage electrode 4 electrically connected or integrated in this and over the electrically isolated by means of a feedthrough insulator 91 from the Encapsulation 1 guided conductor 9 with a high voltage source, such as a against overvoltages to be protected line electrically connected. Accordingly, the electrode 17 "with the groundable electrode 5 is electrically conductively connected or integrated into this and isolated from the enclosure 1 guided conductor 11 is placed on ground.

The field control element 6 consists of one of the electrodes 4, 17 'and 17' '' enclosing subfield control element 6 'and an adjoining thereto Subfield control 6 ", which has the highest electrical potential acted upon section of the varistor column 3 'encloses. As shown the two subfield control elements 6 ', 6 "consist of different ones Composites. The subfield control element 6 'may be cast by, the Subfield control 6 "applied by shrinking or winding become.

If the field control element 6 consists of a single part, it can also be so be formed that it all Varistorsäulen 3 ', 3 ", 3"' in the form of a jacket encloses together.

The residual volume 19 of the gas-tight enclosure 1 is filled with an insulating gas, typically SF ₆ .

LIST OF REFERENCE NUMBERS

1

encapsulation

2

active part

3, 3 ', 3 ", 3' ''

Varistorsäulen

4

High-voltage electrode

5

groundable electrode

6, 6 ', 6 "

Field control

7, 7 ', 7 "

varistors

8, 8 ', 8 "

clamping loops

9, 11

conductor

10

plug contact

12

power connection

13, 14

insulator

15

intermediate electrode

16

power connection

17, 17 ', 17 ", 17"'

electrodes

18

Insulating

19

residual volume

31.32

mounting body

61

insulator

62, 63

field controlling layers

91

The bushing

Claims (14)

Active part (2) for an encapsulated surge arrester having at least one varistor column (3, 3 ', 3 ", 3'''), one (4) at high voltage and an electrode (5) which can be passed to ground potential, and with one after installation of the active part (2) arranged in the enclosure (1) of the arrester between varistor column (3, 3 ', 3 ", 3''') and encapsulation (1) and connected to the high voltage electrode (4) element (6, 6 ', 6" ) for controlling an electric field acting in the interior of the enclosure (1) during operation of the arrester, characterized in that the field control element (6, 6 ', 6 ") is connected to the at least one varistor column (3, 3', 3", 3 '). '') and containing a composite formed by a polymeric matrix and a filler embedded in the matrix, which has a dielectric constant between 5 and 45 and / or a non-linear current-voltage characteristic when loaded with an alternating electric field of up to 100Hz , Active part according to claim 1, characterized in that the filler contains a material of high electrical conductivity and / or high dielectric constant and / or microvaristors. Active part according to claim 2, characterized in that the field control element (6, 6 ', 6 ") contains conductive carbon black or a titanate, in particular barium titanate, and that at least a part of the microvaristors is formed by doped and sintered zinc oxide. Active part according to one of claims 1 to 3, characterized in that the field control element (6, 6 ', 6 ") at least one connected to the high voltage electrode (4) longitudinal portion of the varistor column (3, 3', 3", 3 ''') extends. Active part according to claim 4, characterized in that the field control element is extended over the entire length of the varistor column. Active part according to one of claims 4 or 5, characterized in that at least a portion of the field control element rests on the lateral surface of the varistor column. Active part according to one of claims 4 or 5, characterized in that the field control element is supported by an insulating body (14) held on the lateral surface of the varistor column. Active part according to one of Claims 4 to 7, characterized in that the field control element has at least two field-controlling layers (62, 63) which are separated from one another by an electrically insulating layer (61). Active part according to claim 8, characterized in that the field-controlling layers (62, 63) have different electrical properties and / or extend differently far over the length of the varistor column. Active part according to one of claims 4 to 9, characterized in that the thickness of the field control element varies transversely to the column axis over the length of the varistor column. Process for producing the active part (2) according to one of Claims 1 to 10, in which a stack of varistors (7, 7 ', 7 ") and two connecting electrodes (4, 5, 15, 17, 17', 17", 17 ''') are clamped to form a mounting unit (31, 32) containing the varistor column (3, 3', 3 ", 3 ''') or a section of this column, and subsequently the field control element (6, 6', 6") is attached to the mounting unit (31, 32), characterized in that the field control element (6, 6 ', 6 ") on the varistor column (3, 3', 3", 3 ''') or an insulating body surrounding the varistor ( 14) is applied. A method according to claim 11, characterized in that the field control element is applied by casting or injection molding of the filled polymer or by shrinking or winding a filled polymer holding the supporting body. Enclosed surge arrester with one active part (2) after one of claims 1 to 10 receiving, finger-safe executed Encapsulation (1). Arrester according to claim 13, characterized in that a residual volume remaining in the enclosure (19) between encapsulation (1) and active part (2) is filled with solid, liquid and / or gaseous insulating material.

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