DE1963324C3 - Electrically insulating coating compound - Google Patents

Description

35

Table 1

salary
of water-soluble ions in accumulations of dust

Dust sampling location

4 » Steel factory A
Steel factory B
Power plant ..

Water soluble Cl- Ions soi- Vl NO ₃ - · / « 3.04 · / · 11.0 1.01 0.05 18.5 0.59 0.42 12.3 -

The present invention relates to insulating compounds for electrical machines and devices are useful, and in particular it relates to electrically insulating coatings, which are one by the Environment or the atmosphere in which they are used caused a decrease in insulation resistance and with their help a decreased insulation resistance can be quickly restored can be.

The insulation resistance of electrical machines and devices used in areas or factories with polluted atmosphere or placed on the sea coast, takes longer during operation Time due to adsorption, separation or accumulation of gas, water vapor, mist, Dust or moisture od. The like. Gradually from, which ultimately leads to severe disturbances, such as short circuit and burn out, leads. Such tendencies are caused by severe pollution of the atmosphere with sulfur dioxide gas, by agglomeration of factories and cities in coastal areas, increase the mains voltage and more recently by the The conditions under which an accelerated Decrease in insulation resistance and breakdown of insulation caused by electrolytes can occur are the following:

1. A deterioration is accelerated especially at a humidity of more than 90%, however rarely occurs at a humidity of less than 30Vo.

2. Deterioration depends on the moisture absorption of reactive residues the insulation, but not its electrical properties.

3. It fluctuates depending on the applied voltage.

As already described above, the surface condition of insulators is only slightly influenced by Electrolytes deposited from the atmosphere with low humidity (less than 30%), with increasing humidity, however, stock!

55

60

I 963

the moisture on the surface of the insulator or diffuses into the surface of the insulator into it to form molecular water films. If electrolytes are present in the water film, so become anions and cations with a degree of freedom corresponding to the number of ions passed formed in the water film and thus make it conductive, which increases the insulation resistance of the insulating material decreases. In addition, the applied voltage causes a transfer of metals Stray current, local overcurrent, electrical discharge, tracking, charring and others causes undesirable phenomena, which leads to the burning of the Isoliennatedals.

The process of degradation of the insulation resistance of insulating material caused by salt is as follows: The salt components deposited on the surface of the insulator in the form of mist or dust (e.g. sodium chloride) are separated or absorbed by the highly humid atmosphere Water film dissociates to form electrically conductive anions and cations. More accurate:

electrolyte
Na Cl
(non-conductive)

under high
Moisture ^ions

under lower
humidity

Na ⁺ Cl-

(conductive)

Practically applied, however, they are not applied to all insulation materials or components need insulation, applicable. On the other hand, the surface treatment is - <ur implementation the measure 3 relatively simple and advantageous.

The object of the present invention is to provide an insulating coating composition that can do this

ίο is able to remove anions and cations that formed by dissociation of electrolytes in films of water.

The invention relates to an electrically insulating coating compound which is used as an insulating material Metal parts with different efektrisefeen Potentials can be used, which is characterized in that they are a mixture of cuiet Coating base component, which is hydrophilic and does not hinder ion migration, a cation exchange resin, an anion exchange resin and solvent.

That used in the present invention Main coating material should allow deionization (desalination) of the ion exchange resin:

1. it should therefore be hydrophilic,

2. it should not hinder ion migration,

Under the influence of applied voltage, these anions and cations migrate through an aqueous solution or a Vssserfilm to the cathode or anode and transport loads, which they use to direct the Dektic. One can say that a stray current leads to a destruction of the insulation strength.

At the same time, an electrolytic dissociation also takes place in the water (H ₄ O ^ H ⁺ + OH-). However, since the electrolytic dissociation constant of water is 1.8 · 10- »(at 25 ° C) and the resistance is 6.3 - ΙΟ" ohms / cm (at 25 ° C), the dissociation does not affect the electrical resistance, so that ions which impart conductivity to the water film are considered to be electrolyte compositions contained therein.

Thus, the deterioration in electrical insulation can be attributed to the ions caused by Electrolytes are formed which are deposited or adsorbed in the on the surface of the insulator Moisture are contained.

Accordingly, the following measures can be taken to prevent the deterioration or to prevent the insulator from burning out.

1. Lowering the humidity of the atmosphere to less than 30 ° / · in order to prevent the formation of To prevent water films.

2. Use of dust-tight or completely closed structures to prevent the build-up of To prevent electrolytes.

3. Removal of electrolytically dissociated ions to allow the formation of electrically conductive films impede. Measures 1 and 2 are

3. It should have good adhesiveness, water resistance, moisture resistance, weathering and aging resistance own, and

4. It should have other properties that are required for the base component of the coating composition are.

The basic components of the coating compound, which have the properties described above, include resins that consist essentially of organic acids that contain hydrophilic residues (e.g. shellac, turpentine, copal resin); Cellulose derivatives that contain several hydroxyl groups in the molecule (e.g. cellulose acetate, ethyl cellulose, Cellulose acetate butyrate); and polar resins that are highly permeable to ions (e.g. acrylic resin, polyvinyl chloride, Vinyl acetate, silicone alkyd resin, etc.).

In addition to the basic components of the coating, the film-forming auxiliary components include the if desired, desiccants, binders, plasticizers can be added to the composition Dispersants, emulsifiers and the like. These auxiliary components are used to prepare the dispersion of the coating components, the drying, setting and atJerc physical properties of the applied To improve the film. A solvent or thinning agent can also be used as an auxiliary component can be used to improve the peelability of the coating mass. As a pigment, eir Body pigment can be used.

The reaction mechanism of the cation and anion exchange resin is as follows when removing cations and anions (Na ⁺ and Cl "are taken as examples for the cation and anion):

Desalination activity Cl i RH · R 'OH> R Na -f- R' Cl \ H., O

therein R H represents the cation exchange character / and R 'OH represents the anion exchange resin. R Na represents the structural formula in which the potassium exchange resin is associated with Na 'ions, whereas R 'Cl represents the structural formula in which the anion exchange resin is combined with Cl "ions.

Of the ion exchange resins used in the present In the present invention, strong electrolyte type resins and weak electrolyte type resins can be cited which can be classified as follows:

1. Strong electrolyte type resins:
Strongly acidic resin (cation exchanger) that uses sulfonic acid residues as exchanging residues.

Strongly basic resin (anion exchanger), the quaternary ammonium groups as exchanging Leftovers used.

2. Weak electrolyte type resins: Weakly acidic resin (cation exchanger) which uses carboxyl groups or phenolic hydroxyl groups as exchanging groups.
Weakly basic resin (anion exchanger) that uses primary, secondary and tertiary amines as exchanging groups.

The coating compositions of the present invention pass through those contained in the compositions Cation and anion exchange resins, the above-described desalination reactions, wherein the cations and aniorien are removed from the water film and thus a deterioration of the Isolation material is effectively prevented.

To the drawings:

F i g. 1 shows a graph showing the effect of relative humidity on the specific Illustrates surface resistance of electrically insulating materials;

F i g. 2 shows the effect of relative humidity on the resistivity of electrically insulating Materials;

F i g. 3 and 4 are a plan view and a side sectional view of one used in Example I, respectively Test piece, and

F i g. 5 and 6 are a plan view and a side view, respectively. partly in section, of a Tcst clamp holder used in Example 2.

The following specific examples are intended to illustrate the present invention.

Example I.

This example illustrates one method of making the new coating composition and its Function which consists in preventing a drop in insulation resistance.

The ion exchange resins used in this example were weak electrolyte type resins as shown in Table 2 below.

Table 2
Ion exchange resin

resin Slightly acidic
Cations
exchange resin Weak
basic
Anion
aiislauscherharz Exchanging rest
Type
Water content
Particle size
Total exchange
capacity mg-equi-
valent / g dry
resin COOM
H type
5 to 10 per cent
0.074 to
0.037 mm
(200 to
'400 mesh)
10.0 Polyamine
OH type
5 to 10 ¹ Vo
0.074 to
0.037 mm
(200 to
400 mesh)
10.0

In this, M means metal or hydrogen.

The ion exchange resins given in Table 2 were incorporated into the basic components and with the basic components and auxiliary components of the coating composition in the form indicated in Table 3 given conditions mixed and kneaded

Table 3
Ratio of components (° / o)

Components

A.l

Designation of the coating compound

B.
BI I B.2

Cl

C.2

Thermoplastic acrylic resin.

Vinyl acetate-vinyl chloride copolymer

Nitrocellulose

Alkyd resin

Rosin

Plasticizers

Weakly acidic cation exchange resin

Weakly basic anion exchange resin

total

90.0

5.0

5.0
100.0

26.9

40.8

14.2

8.2

5.0

5.0
100.0

21.0
31.5

11.1

6.4
15.0

15.0
100.0

90.0

5.0

5.0
100.0

70.0

15.0

15.0
100.0

/ 1 7 C R

Coating compounds produced in this way were applied to insulating panels and their iso-outer properties Were tested. The holierplntten * arcn built from Prieiu-ilharz-1.aniinaten, owned the dimensions 50 20 3 mm and the arrangement shown in FIGS. 3 and 4 with an insulating plate 1, copper rods 2 and screws 3 for fastening the electrodes. The coating compounds were sprayed on. After application, the applied tiles were air-dried, and The copper backs were then 2 (15 10 2mm) fastened in it with screws 3 at a distance of H) mm.

The test panels tested in this way are listed in Table 4.

Table 4
Isolation plates for testing the insulating properties

No. of
Test plate Transfer treatment 1 not covered 2 not covered 3 covered by spraying with sample A.l in table 3 4th covered by spraying with sample A.2 in Table 3 covered by spraying with sample B.l in table 3 6th covered by spraying with sample B.2 in Table 3 7th covered by spraying with sample CI in Table 3 8th covered by spraying with sample Cl in Table 3

To determine the effect that a drop in insulation resistance with the new coating compounds is prevented, a 10% sodium chloride solution was used sprayed onto the surface of the test plates shown in Table 4 which carried electrodes and the insulation resistance of the test panels before and after the application of the saline solution Measured with the help of a megohmmeter with an applied electrode voltage of 500 volts The test result is shown in Table 5.

From Table 5 it can be clearly seen that when comparing with untreated panels, those with the Insulating panels coated with new coating compounds show great resistance to saline solution show caused decrease in insulation. In particular, the new masses have the thermoplastic Acrylic resin contained as a basic component, an insulation resistance of more than 1000 megohms, after applying a large amount of saline, whereas the insulation resistance "On insulating plates that were not coated with the new masses, dipped to just a few megohms is. In this way the new overlapping masses have a remarkable effect, iniem they prevent a deterioration in the insulating capacity of τοπ insulators. It goes without saying that the amount of cation and anion exchange resins does not fall below the values given in Table 3 Values is limited, the preferred range is 0.5 to 35 percent by weight for each exchanger

Table 5

Drop in insulation resistance
by spraying with saline solution

Insulation resistance Isolation opposition 700 megohms before spraying after spraying Test plans with saline solution with saline solution 630 megohms Spraying time with saline solution - 1 minute more than 1 10,000 megohms 10,000 megohms 2 5,000 megohms 3 6,000 megohms 4th 3,000 megohms 5 3,000 megohms 6th > - 3 minutes 7th 2 megohms 8th 5 megohms more than 10,000 megohms 15,000 megohms 1 more than 10,000 megohms 2,000 megohms 2 more than 10,000 megohms 1,000 megohms 3 more than 10,000 megohms 1,000 megohms 4th more than 10,000 megohms 400 megohms 5 more than 10,000 megohms 500 megohms 6th more than 10,000 megohms 7th more than 10,000 megohms 8th Spray time with saline solution more than 10,000 megohms more than 10,000 megohms more than 10,000 megohms more than 10,000 megohms more than 10,000 megohms more than 10,000 megohms more than 10,000 megohms more than 10,000 megohms

The following example shows the recovery of the insulation resistance with the help of the new coating compounds.

Example 2

About the effect of regaining the insulation resistance with the help of the new coating compounds to show, terminal holders were selected whose insulation resistance has actually already been

was sunken.

The ion exchange resins used in this example were the same weak electrolyte type resins as used in Example 1 and are given in Table 2. This

Ion exchange resins were made with basic and auxiliary components the coating composition in accordance with the formulation given in Table 6.

409 639/291

ίο

Table 6 Proportion of components ( ¹ V

Components

Cellulose triacetate

Themonlastic acrylic resin

Turpentine shark

Weakly acidic ion exchange resin

Weakly basic ion exchange resin

total

Coating Compound D I E

60

10.0

Ii) ₁ O

lii.O 100.0

60.0 10.0

15.0

15.0 100.0

The clamp holders tested consisted of molded insulating plates with silver-plated plates embedded therein Copper plate clamps and were 7 years long been used in a substation.

According to their seven years of use, the surface area of the clamp holders was considerable contaminated with dust and other foreign substances. The insulation resistance between terminals is strong dirty clamp holder was 50 to 500 megohms compared to not more than 10,000 megohms dirty clamp holder. The clamp holders tested had the ones shown in FIGS. 5 and 6 shown Arrangement and dimensions with the insulating plate 11,

ίο the silver-plated copper terminals 12 and the dirty one Regions 13.

Terminal holders so badly soiled that the insulation resistance between the terminals had dropped to less than 500 megohms were selected and the coating compositions shown in Table 6 were applied to the soiled regions between the terminals with the aid of a brush.
The restoration of the insulating capacity that comes with

Table 7 shows that the new coating compositions were achieved.

Table 7
Restoration of the insulation resistance

Coating material

before the

Apply

of the coating

Insulation resistance immediately after

Apply after

of an hour's ^cover

after four days

Temperature at the time
the measurement ....

Humidity at the time
the measurement ....

Tested
Clamp holder

Coating table D

of Table 6 was

applied with a brush

Coating Compound E

of Table 6 was

applied with a brush

22.0 C

70Vo 170 megohms

300 megohms 22.0 ° C

700/0
150 megohms

250 megohms

21.5 ^; 1C

70 ° / o
1400 megohms

1500 megohms

17.5 ^° C

70 ° / o
6000 megohms

5000 megohms

This table shows that with the help of the new access 45, and the change in its insulation resistance

Compositions the insulation resistance has been widely used under the same temperature and temperature

walking can be recovered. Measured for moisture conditions. It was found that

A clamp holder was selected immediately, the insulation resistance of which increased to 200 mega-

Insulation resistance had dropped to 400 megohms.

For this purpose 2 sheets of drawings

Claims (6)

Patent claims: 1. Electrically insulating coating compound, which is used as an insulating material between metal parts with different electrical potentials can be used, characterized in that that they are a mixture of a coating base component, which is hydrophilic and ion migration not hindered, a cation exchange resin, an anion exchange resin and Contains solvent 2. Coating composition according to claim 1, characterized in that it contains one or more drying agents, Contains binders, plasticizers, dispersants, emulsifiers and / or pigments 3. Coating composition according to claim 1, characterized in that the basic component of the coating resins made from organic acids, which contain hydrophilic residues, cellulose derivatives, which contain several hydroxyl groups in the molecule, and / or polar resins, which are highly permeable to ions are used. 4. Coating composition according to claim 1 or 2, characterized in that the cation is as exchanger resin is a strongly acidic resin that contains sulfur residues, or a weakly acidic resin that Contains carboxyl groups or phenolic hydroxyl groups. 5. Coating composition according to one of the preceding claims, characterized in that that as anions of resin a strong basic resin that contains quaternary ammonium residues or a sch. '' oh basic resin, which contains amine residues 6. Coating composition according to claim 1, characterized in that the anion exchange resin in each case and the cation exchange resin in an amount of 0.5 to 35 · / ·, based on the Total weight of the coating mass, incorporated 4 ». 30 efforts to make electrical machines and work-related requests compact are required. ⁸ ^ ⁵ JoE already mentioned, the deterioration of electrically insulating materials is also caused by the absorption of moisture ^F On d £ e ² wffie 'decreases by the absorption of Feuchtiekeit the surface resistivity voÄuermaterialien heavily on, and the presence eTnes electrolyte on the surface of IsohermaSriSs deteriorated rapidly to IsolmrwidersUmd J 7ch _and the formation of a water film Various electrolytes in the form of gas , Vapor, mist and dust contained in the atmosphere are adsorbed or accumulated on the surface of the insulating material. For example, the decrease in insulation resistance caused by salt, which often occurs in coastal areas, is caused by fog or dust that contains electrolytes such as sodium chloride and the like from seawater. In addition, the decrease in insulation resistance is caused by water-soluble ions such as SO ₄ , Cl- NO-, Mg ²⁺ , K ⁺ , Na ⁺ , Ca ²⁺ , NH ₄ ⁺ , etc., which are contained in fog 'or 5th deaf in the polluted atmosphere. Table 1 shows typical examples of the content of water-soluble ions contained in dust, which was produced by steel factories and electrical! energy supplying plants.