EP0807310B1 - Insulator with cemented joint and process for producing it - Google Patents

Abstract

PCT No. PCT/EP96/00226 Sec. 371 Date Aug. 27, 1997 Sec. 102(e) Date Aug. 27, 1997 PCT Filed Jan. 19, 1996 PCT Pub. No. WO96/24144 PCT Pub. Date Aug. 8, 1996The invention relates to an electrical isolator having at least one fitting cemented onto an insulating body, in which the insulating body is bonded to the fitting via a cement shell, wherein a laminated layer which contains at least two layers of different materials is applied on the fitting between the cement shell and the fitting, wherein at least one of the layers protects the fitting from corrosion and wherein at least one other layer permits movement between the cement shell and the fitting.

Description

The invention relates to an electrical insulator with at least one on one Insulated body cemented armature. Isolators and in particular High voltage insulators are used in large numbers in overhead lines and Outdoor switchgear used. Most isolators consist of one Insulating body with a non-positive and / or positive fit at the ends of the insulating body attached fittings in the form of metal caps. These serve primarily the Power transmission. The outer diameter of the insulated trunk and at Hollow insulators in addition to the wall thickness of the insulator body trunk are all designed according to the mechanical load on the insulator. Each according to the size and type of mechanical stress, the trunk ends and Faucets designed differently. The insulating body and the associated Fittings are usually essentially rotationally symmetrical educated.

The drunkards of the mainly stressed tensile forces Long rod insulators are mostly conical; to the required force or / and positive connection between the insulating body and the fitting the gap between the insulated trunk and the valve usually cast with a lead alloy.

Support or / and hollow insulators have predominantly cylindrical trunk ends. Such trunk ends are often round or at the socket crushed crushed stone, which is sintered in a glaze layer; this improves as well as corrugations, corrugations or rough areas in the area the socket the positive and / or positive connection. The gap between the valve and shank end is usually with setting or hardening Putty materials such as Cement mortar filled out. Especially with support or / and hollow insulators become the cylindrical, split trunk ends often with a lean Portland cement with a non-positive and / or positive fit connected to a fitting, usually made of galvanized cast iron or one Aluminum alloy is made.

EP-A-0 615 259 teaches a method of making a putty joint between an insulating body and a fitting, in which the cement gap only with partially filled with a quick-curing first putty and then with a slowly setting second putty is filled.

From EP 0 613 156 A1 an isolator is known, the armature for Fastening for protection against corrosion by a bitumen layer against the Putty, a cement, is insulated. This version is as of Technique shown in Figure 1. The invention is shown in FIG. There is the valve without insulation layer by means of a polyurethane layer directly on Insulator attached. The polyurethane layer is said to move when vibrated allow between isolator and valve.

In US-PS 4,316,054 there is a connection between a fitting and a Insulator shown, on which a resin mass is first applied. This Resin compound carries a so-called resilient cap, an elastic layer which has shrunk a metal shell. This metal shell separates the cement from the the elastic layer allows movement. The fitting is directly adjacent the cement without a layer protecting the valve from corrosion is provided.

It is known to paint the inside of the fittings with a bituminous paint to protect against the chemical attack of Portland cement / mortar. Water that is in the gap between the tap and the end of the trunk can both during setting of the Portland cement / mortar, as well as during Use of the high voltage insulators in a humid climate by reaction with the Cement / mortar develop a pH of around 12 to 13. Furthermore Embodiments are also known in which instead of the bituminous Painting a curing epoxy resin paint or Resin coating with embedded quartz sand grains is selected.

The embodiments according to the prior art - if by one occasionally applied adhesive layer applied to the valve that should improve the adhesion of the subsequent coating - only one only layer between the fitting and the set putty containing kit bowl. This single layer can consist of several layers of the same material. It has been determined in experiments that it works with this one layer between armature and kit bowl according to the state of the Technology is not possible with both high bending moments Attempting to wrap, as well as a low permanent valve movement to be implemented after routine tests with bending or / and internal pressure loading. Either - as with bituminous paints - after routine tests according to EN 50062 high permanent valve displacements and in Trying to achieve high bending moments or the permanent ones Faucet shifts were - as with epoxy or sanded Synthetic resin painting - low, whereby at the same time there is an increased susceptibility to Disc breaks and low bending moments resulted. As a broken window is the peeling of the insulating body at its ends essentially perpendicular to the longitudinal axis designated.

The permanent valve displacement is the one day after routine tests still existing displacement between the underside of the valve and the end face of the insulation trunk as a result of the previously applied routine test load according to EN 50062, DIN VDE 0674, Part 3, November 1992, in relation to the position before the routine test load. The valve is mainly moved in the longitudinal direction of the isolator and also tilts when the forces are applied laterally. It can be connected to an expansion of the valve circumference. The position of the fitting is measured by means of a dial gauge as the distance between the ground insulating body face and a flat, position-marked bar placed on the fitting face every 90 ° in the direction of the longitudinal axis of the insulator; The largest difference value determined on a valve between assigned measured values before and after routine tests is used as the value for the permanent valve displacement. The greater the permanent movement of the fittings and the greater the disruption of the kit shell due to movements between grit and kit shell, the greater the risk that a sealing system placed on the face of the insulating body is not permanently gas-tight. Leaks in the device insulators filled with SF ₆ gas must be avoided.

The break attempt is one of the more frequently performed mechanical tests, where a hollow insulator is subjected to a bending test in accordance with EN 50062, DIN VDE 0674, Part 3, November 1992, in a multi-stage trial maximum resilience and is therefore tested until it breaks. Isolators that are not hollow insulators, can in a similar way according to IEC 168, 1988, being checked. Here, the insulator is firmly clamped at the foot end and on opposite end drawn perpendicular to its longitudinal axis. Under the The bending stress becomes the maximum load that can be tolerated Understood.

The invention has for its object an insulator with a putty connection propose both a high bending moment and a low one permanent valve movement guaranteed. In addition, the Task to make the manufacture of such isolators as simple as possible.

This object is achieved with an electrical insulator solved at least one fitting cemented onto an insulating body, in which the insulating body is connected to the fitting via a kit shell, which thereby is characterized in that on the fitting between the kit bowl and the Armature a layer composite is applied, which consists of at least two layers contains different materials that at least one of the layers Fitting protects against corrosion and that at least one other layer is a Allows movement between kit bowl and fitting.

There are preferably two, three or four between the kit bowl and the fitting different layers applied. Each of these layers can be made several layers of the same material. One of those layers can be an adhesive layer applied directly to the valve, which the Adhesion between the fitting and the second one applied to the fitting Layer should improve.

The insulator can u. a. made of ceramic or glass according to IEC 672, 1980, exist. The fittings usually consist of galvanized Cast iron or an aluminum alloy. The shapes of the fittings are specifically designed. You can have a sawtooth profile on the Have side facing the socket. The kit bowl is there usually from a set or hardened putty material.

The layer of the laminate facing the valve, which the valve of Protects corrosion, has a layer thickness of 5 to 1000 microns, preferably from 20 to 500, in particular from 80 to 200 microns. This layer consists of Use of mortars or cements from an alkali-resistant layer, preferably from alkali resistant corrosion protection materials such as. B. cast resin, reaction or synthetic resin paint, particularly preferably made of two-component epoxy resin. The anti-corrosion material is preferred sprayed or spread.

The slippery layer of the laminate, which is a movement between Kit tray and fitting enables and catches, can rather a subordinate Have anti-corrosion function. You can directly on the Corrosion protection layer must be applied. This layer can consist of one Bitumen-containing paint, from another lubricious Paint or a lubricant such as Lubricants based Molybdenum disulfide or graphite, metal lubricants, lubricating varnishes, greases and / or Oils exist. The material of this layer must be against the putty material Kit bowl made of hardened or water-set putty material and also be largely resistant to the water it may contain. It can be spread or sprayed onto the coated fitting. The layer thickness of this layer can be 2 to 1000 μm, preferably 5 to 200 μm, in particular 10 to 80 microns.

Furthermore, the object is achieved by a method for producing a electrical insulator with at least one cemented onto an insulating body Fitting released, in which the insulating body is connected to the fitting via a kit bowl is connected and that is characterized in that the kit bowl facing inside of the valve with at least one Corrosion protection layer and the movement between the kit shell and Armature-enabling layer is coated.

Mainly mortar and cement can be used as cement material. Under The mortars and cements is a grouting mortar that is easy to install in the Gap cast between the trunk end of the insulating body and the fitting is particularly easy to process and because of the quick setting Cheap. In addition, a grout does not need like other mortars and Cements to be shaken.

The combination with several layers between the fitting and kit bowl can be used all known valve and insulating body materials are used, using cement, mortar or similar putty materials and, if necessary be cemented with the addition of other substances. The isolators according to the invention, especially high-voltage insulators, are particularly suitable as support or / and hollow insulators. The individual layers can usually be Sawing the fitting and scratching the layered composite visually well perceive.

It was surprising that the task could only be accomplished by using at least two layers with different composition of matter and with different properties of the layer materials, wherein the layer facing the kit shell is necessary in order to to enable controlled relative movement between the kit bowl and the fitting, to absorb the forces that occur and the kit bowl in the Tension the fitting so that both high bending moments and also small permanent valve movements due to a controlled Sliding movement can be achieved.

One applied between the sintered split layer and the kit bowl Layer of bituminous paint has on the permanent Fitting movement has little or no impact. This layer preferably has an adhesive effect and with regard to the different Thermal expansion has a dampening effect, especially between the insulating body and Kit bowl.

In the following, the invention is exemplified using an embodiment explains:

Figure 1 shows a longitudinal section through a hollow insulator in the area around the Socket. The insulating body 1 has one in its center In the longitudinal direction extending, cylindrical cavity 2. In the field of Socket 3 is applied to the surface of the insulating body 1 grit 4, which can be sintered with a glaze and possibly also an additional layer 5 can have bituminous paint material. The armature 6 shows a sawtooth-like profile on the side facing socket 3 and is covered with a layer composite 7 from two layers 8 and 9. The Corrosion protection layer 8 is one of the movement between armature 6 and kit shell 10 enabling and catching lubricious layer 9 overlaid. The gap between the insulating body 1 and armature 6 is mainly with set or hardened putty material that forms the kit shell 10, filled out. The slippery layer 9 occurs after and for a limited time a load a relative movement between the valve and the kit bowl takes place: When loaded, approximately in the direction of the arrow, then in approximately opposite direction. The insulating body end face 11 is approximately parallel to the valve face 12.

Figure 2 shows the detail II of Figure 1 enlarged.

In the following, Examples 1 and 2 are used as comparative examples and Examples 3 to 6 according to the invention are explained in more detail:

A so-called medium-sized earth insulator was used for the tests selected, which is common and for operation as a hollow insulator at 145 kV is provided. The insulating bodies of the test specimens were made of alumina porcelain. The cylindrical trunk ends had one in the area of the socket Outside diameter of approximately 200 mm. Then there was a round grit applied, which was sintered with a glaze; on it became a bituminous Paint applied. The fittings consisted of the aluminum alloy G-AlSi10Mg wa and had an internal sawtooth profile. The Fittings were covered over the entire inside with the in Table 1 specified materials coated. The coatings were applied by spraying. Other parameters influencing the cementation were kept constant.

The structure of the layers and the results of the tests are listed in Tables 1 and 2. The layer thicknesses were measured eight times over the valve circumference and are approximate values for the slightly fluctuating layer thickness. Structure of the layers. The layer thicknesses are averages over several tests. The layer thickness of the assembly spray was not determined. example Corrosion protection layer moving layer VB 1 99 µm bituminous paint is missing VB 2 162 µm epoxy resin is missing B 3 114 µm epoxy resin Assembly spray B 4 140 pm epoxy resin 28 µm bituminous paint B 5 144 µm epoxy resin 13 µm bituminous paint B 6 137 µm epoxy resin 58 µm bituminous paint

The following routine tests were carried out one day before the break attempt carried out: First a bending test to 70% of the nominal bending moment 3 test specimens produced in the same way and then one Internal pressure test with a one minute hold time according to EN 50062 up to approximately 70% of the minimum burst pressure. In the bending tests, the upper and lower ends tested separately; the force was introduced on cylindrical porcelain body outside the fitting. The test subjects were at Bending test, each offset by 90 °, loaded for 10 s. In the Subsequent visual inspections were performed on none of the examinees Damage found as a result of routine tests. On the day of The permanent valve movement resulting from the Bending test and the internal pressure test, determined.

The break test was carried out in the same orientation of the insulator to the test apparatus as in the fourth loading of the bending test. The load was applied until the hollow insulators broke by bending. In each experiment, the three insulators were broken at the top and bottom. Here, 8 strain gauges were attached perpendicular to the longitudinal direction of the insulator on the outwardly projecting edge of the fitting of each fitting in order to determine the fitting expansions. The values of the bending moments were averaged from 6 measured values in each case. Results of the experiments. example permanent valve movement Bending breaking moment mean minimum Valve expansion mm kNm kNm µm / m VB 1 0.152 41.55 36.00 542 VB 2 0.019 34.02 20.70 292 B 3 0.052 43.05 30.00 513 B 4 0.007 37.60 29.30 488 B 5 0.032 48.40 43.70 nb B 6 0.015 46.70 43.50 nb

As the test results shown in Table 2 show, at the examples according to the invention compared to the comparative examples sufficiently high bending moments and low permanent ones Valve shifts achieved. Compared to the variant with Epoxy resin paint (VB 2) could measure the smallest Bending moment can be increased by about 50%. The permanent one Valve displacement is in the range of very low Fitting the variant with epoxy resin paint (VB 2).

The measured values for the valve expansion, which are used in the wrapping tests according to EN 50062 measured at a nominal bending moment of 20 kNm, confirm as it is known analogously from shrink connections that high Radial stresses allow high bending moments. The measured high Strain values are based on a relative movement between the kit shell and Fitting, in which the fitting essentially in the longitudinal direction of the isolator Kit case is pulled away from the insulating body; here the fitting is sawtooth-like profile of the fitting and the kit bowl expanded in diameter. The moveable layer is crucial for the high valve expansion Load on the putty. This results in a high on the kit bowl effective radial stress with the consequence of high break values. Farther is released when the kit tray is relieved at the end of each mechanical test controlled slide back of the valve and thus a low permanent Valve shift reached.

Claims (13)

1. Electrical insulator having at least one metal part (6) cemented to an insulating body (1), the insulating body (1) being connected by means of a shell of filler (10) to the metal part (6), characterised in that between the shell of filler (10) and the metal part (6) there is applied to the metal part (6) a laminate composite (7), which contains at least two layers (8, 9) of different materials, at least one of the layers protects the metal part against corrosion and at least one other layer allows movement between the shell of filler (1) and the metal part (6).
2. Electrical insulator according to claim 1, characterised in that the layer (8) having the anti-corrosive function has a layer thickness of from 5 to 1000 µm, preferably from 20 to 500 µm, especially from 80 to 200 µm.
3. Electrical insulator according to claim 1 or 2, characterised in that the layer (9) allowing movement between shell of filler and metal part has a layer thickness of from 2 to 1000 µm, preferably from 5 to 200 µm, especially from 10 to 80 µm.
4. Electrical insulator according to any one of claims 1 to 3, characterised in that two, three or four layers of different materials are applied to the metal part (6).
5. Electrical insulator according to any one of claims 1 to 4, characterised in that one of at least three layers is an adhesion-promoting layer applied to the metal part (6).
6. Electrical insulator according to any one of claims 1 to 5, characterised in that in the region of a base part (3) a grit layer (4) is applied to the insulating body (1), to which grit layer a layer (5) of a bituminous coating material is preferably applied.
7. Electrical insulator according to any one of claims 1 to 6, characterised in that the layer (8) having the anti-corrosive function contains a casting resin or a reaction resin or synthetic resin lacquer, especially an epoxy resin.
8. Electrical insulator according to any one of claims 1 to 7, characterised in that the layer (9) allowing movement between shell of filler (10) and metal part (6) contains an anti-friction coating material or lubricant.
9. Electrical insulator according to claim 8, characterised in that the anti-friction coating material or lubricant is a bitumen-containing coating material, lubricant based on molybdenum disulphide or graphite, anti-seize lacquer, metal lubricant, grease or oil.
10. Method for the manufacture of an electrical insulator having at least one metal part (6) cemented to an insulating body (1), the insulating body (1) being connected by means of a shell of filler (10) to the metal part (6), characterised in that the inside of the metal part (6) facing the shell of filler (10) is coated with at least one layer (8) having an anti-corrosive function and a layer (9) allowing movement between the shell of filler and metal part.
11. Method for the manufacture of an electrical insulator according to claim 10, characterised in that the material for the layer (8) having the anti-corrosive function is spread onto or sprayed onto the metal part (6) or onto an adhesion-promoting layer applied to the metal part (6).
12. Method for the manufacture of an electrical insulator according to claim 10, characterised in that the layer (9) allowing movement between the shell of filler (10) and the metal part (6) is spread onto or sprayed onto the coated metal part (6).
13. Method for the manufacture of an electrical insulator according to any one of claims 10 to 12, characterised in that a casting compound is poured as filler material into the gap between insulating body (1) and coated metal part (6) and sets there.

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