JPH0664958B2 - Polyester premix parts for high voltage equipment - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a polyester premix component containing calcium carbonate powder for high-voltage electric equipment, and more particularly to an insulating component requiring acid gas atmosphere resistance.

[Conventional technology]

Polyester premix parts have been evaluated for their excellent shapeability, thermal stability, electrical insulation performance and mechanical strength, and have been used for high voltage electrical equipment such as high voltage switchgear, substation equipment and rotating electrical machines. It is often used as an insulating support component or mechanical transmission component. For these high-voltage equipment parts, a bread-type premix in which a large amount of filler powder is added to unsaturated polyester and a little glass fiber is further added to a desired shape using a compression molding machine, transfer molding machine, injection molding machine, or the like. It is obtained by hot pressing and hardening treatment, but one using calcium carbonate (CaCO ₃ ) as a filler powder is widely known.

[Problems to be Solved by the Invention]

When high-voltage electrical equipment using polyester premix parts is installed in places such as water purification plants and pools where chlorine gas (Cl ₂ ) is often used for sterilization, or in places with high exhaust gas concentrations such as in automobiles, etc. The surface resistance (electrical insulation resistance) of the mixed parts decreased, and the phenomenon that the surface resistance was not easily recovered by just wiping the surface of the parts frequently occurred, which caused an increase in the leakage current to the ground and detected this. There are also situations in which the circuit breaker operates and an unexpected power failure occurs.

An object of the present invention is to prevent the reduction of the surface resistance without changing the shape or composition of the component based on the result of the investigation of the cause of the reduction of the surface resistance.

[Means for Solving the Problems]

In order to solve the above problems, according to the present invention, a polyester premix molded product containing calcium carbonate powder as a filler, an epoxy resin coating material for preventing the permeation of an oxidizing substance into the molded product on the surface The protective layer is formed by applying the protective layer.

[Action]

In the above means, calcium carbonate particles as a filler are distributed and exposed on the surface of conventional polyester premix parts, and the concentration of acidic gas such as chlorine (Cl ₂ ) and nitric oxide (NOx) is high. In the atmosphere, acidic gas combines with water in the air to form acidic mist, which attaches to the surface of parts, and the calcium carbonate particles exposed on the surface of the parts react with acidic mist and change to deliquescent substances, which causes The surface resistance decreases with time.Since this deliquescence gradually progresses, the decrease in surface resistance becomes noticeable with the passage of time, and it is not possible to recover the surface resistance by cleaning the surface of the component. It was constructed based on the results of the investigation of the polyester priming, in which a part of calcium carbonate particles was exposed by providing a protective layer made of an epoxy resin coating material. The protective layer made of epoxy resin coating material, which has excellent chemical resistance and impermeability, prevents the permeation of acid gas and acid mist and prevents the reaction with calcium carbonate particles. Functioning, the protective layer is mechanically strong, is not easily damaged, and has high insulation performance, so it can be used in an atmosphere with high acid gas concentration without affecting the shape, composition, and performance of polyester premix parts. On the other hand, a polyester premix component that can maintain a high surface resistance is obtained.

〔Example〕

 The present invention will be described below based on examples.

FIG. 1 is a side view of an air load switchgear showing an embodiment of the present invention, and FIG. 2 is a schematic sectional view showing a main part of an embodiment part. In FIG. 1, a main contactor 5A insulated and supported by a resin insulator 6A on a base 9 is electrically connected to an arc contactor 5B protruding from the tip of a fuse holder 7 rotatably supported by the resin insulator 6B. By being in contact with each other, a conductive path between the main circuit terminals 7A and 7B is configured to be formed via the fuse 1, and the fuse 1 is melted by using the fusing display lever 2 and the fusing display transmission lever 13 as a base. 9 is transmitted to a trip mechanism portion (not shown), and the pull bar 11 pushes the fuse holder 7 upward in the figure, so that the main contactor 5A, the arc contactor 5B, and the auxiliary contactor 8 are opened. At this time, the arc is cut off in the arc extinguishing chamber 3 to disconnect the main circuit.

The pull bar 11 and the fusing display transmission lever 13 are transmission mechanism parts that mechanically connect the main circuit of high voltage and the base 9 side kept at the ground potential, and are required to have high withstand voltage performance, so polyester premix Parts are used. Further, since the main circuit voltage is applied to the fuse holder 7 for a short time when the fuse 1 is blown, and it is necessary to withstand the mechanical force when the pull bar 11 operates, the portion parallel to the fuse 1 is called a fuse support 12. The portion is formed as a polyester premix component. Thus, even if one air load switch is taken, three types of polyester premix parts 10 are used, and these parts are provided with the protective layer of the present invention.

FIG. 2 is a cross-sectional view showing a pull bar 11 as an example of the polyester premix component 10 of the embodiment, and 21 is a polyester premix molded product molded into a desired shape, the surface of which has a thickness of about 20 μm to 60 μm. Protective layer 22 made of epoxy resin coating material
Is formed. As the protective layer 22, a pull bar 21 made of a polyester premix molded body is prepared by spraying a liquid epoxy resin coating material or a coating method.
It can be easily formed by applying a uniform thickness to the surface of the above, and drying and solidifying this, and the coating material used may be either a room temperature curing type or a heat curing type.

Next, the effect of improving the acid gas resistance of the example will be described in comparison with a comparative example having no protective layer. FIG. 3 is a perspective view showing a test piece used in the experiment. Calcium carbonate powder is about 30 parts with respect to 100 parts by weight of unsaturated polyester.
A premix containing 0 parts by weight and about 50 parts by weight of glass chopped strands has a length of 100 mm and a cross-sectional dimension of 5
A comparative example was formed into a rod shape of mm × 20 mm, and a protective layer made of an epoxy resin-based coating material having a thickness of about 40 ± 20 μm was formed as an example. A test piece 50 for insulation resistance (surface resistance) measurement was provided with a pair of electrodes 51 while maintaining a space.

The test piece contains chlorine gas (Cl ₂ ) of 10 PPm and a relative humidity of 100.
% Ambient temperature atmosphere for 10 days, then take it out into the open air and dry it. Relative humidity 20% to 100%
The surface resistance was measured in the atmosphere. Insulation resistance obtained-
As shown in the relative humidity characteristic diagram in FIG. 4, the comparative example curve 1
01 is several tens of meters even in a dry atmosphere with a relative humidity of 40%
It exhibits a low insulation resistance on the order of Ω and drops to several MΩ on the order of 95% relative humidity. On the other hand, in the example curve 100, the insulation resistance is almost infinite (1000 V, even in a moist atmosphere exceeding 80% relative humidity).
It was proved that the decrease of the surface resistance was remarkably small as compared with the comparative example, such as using a megger) and maintaining 1000 MΩ even in an atmosphere reaching a relative humidity of 100%. In addition, since the insulation resistance of the test piece of the example recovers infinitely and rapidly when taken out in the atmosphere of normal temperature and normal humidity, that of the test piece of the comparative example does not easily recover even to the order of several tens of MΩ. It is presumed that the decrease in the insulation resistance of the test piece of the example is due to the occurrence of dew condensation on the surface of the protective layer.

Next, the reason why the insulation resistance is lowered in the comparative example will be described. Chlorine gas in the atmosphere reacts with water as follows to generate hydrochloric acid (HCl).

2Cl ₂ + 2H ₂ O → 4HCl + O ₂ (1) The generated hydrochloric acid adheres to the polyester premix surface as mist and the calcium carbonate (Ca
CO ₃ ) reacts with calcium chloride (CaCl ₂ ) as follows
To generate.

CaCO ₃ + 2HCl → CaCl ₂ + H ₂ O + CO ₂ (2) In this way, when calcium carbonate without deliquescent changes to calcium chloride with remarkable deliquescent, it adsorbs water in the atmosphere and deliquesces Calcium is ionized as shown below, resulting in electrical conductivity.

_{^{CaCl 2 → Ca 2+ + 2Cl -}} ...... (3) reduction of the surface resistance of conventional polyester premix component is believed caused by the process described above. The acid gas also deliquescent significant calcium nitrate when nitric oxide _{(NOx) (Ca (NO 3} ) 2) is generated.

Since the chemical reaction occurs only in the surface layer, the basic idea of the present invention is to prevent the chemical reaction by blocking the supply of the acidic substance to the surface layer by the protective layer, and its effect. Can be easily known from the characteristic diagram shown in FIG.

The reason for using an epoxy resin-based coating material as the protective layer is that the resulting protective layer is mechanically strong, is not easily damaged, and has excellent acid resistance and its impermeability, thus providing an excellent protective action. This is because it can be expected, and even if dew condensation occurs on the surface of a component and a leakage current is generated, tracking deterioration is less likely to occur and the durability is excellent.

〔The invention's effect〕

As described above, the present invention is configured to provide the protective layer made of the epoxy resin coating material on the surface of the polyester premix molded body containing the calcium carbonate powder as the filler. As a result, the calcium carbonate particles exposed on the surface of the conventional molded body react with chlorine gas and oxygen gas contained in the atmosphere and the acid mist generated by combining these with moisture in the atmosphere to change into a substance with remarkable deliquescent, The problem that the surface resistance decreases due to this is essentially eliminated by the fact that the protective layer blocks the supply of the acidic substance to the surface of the molded body, and the reaction itself that causes the decrease in the surface resistance is blocked. To be done. Further, by using the epoxy resin coating material for the protective layer, a strong protective layer excellent in acid resistance and impermeability of acidic substances is formed. Therefore, synthetically these, there is no decrease in surface resistance in an atmosphere with a high acid gas concentration and no increase in leakage current due to this, and a polyester premix part utilizing the features of the polyester premix molded article is obtained, It can contribute to the improvement of insulation reliability of high-voltage equipment.

[Brief description of drawings]

FIG. 1 is a side view showing an example of an embodiment apparatus of the present invention, FIG. 2 is a sectional view of a main part showing an example of an embodiment component, and FIG. 3 is a perspective view showing an insulation resistance test piece. FIG. 4 is a characteristic diagram showing an insulation resistance-relative humidity curve of the test piece of the example in comparison with the conventional example. 10 ... Polyester premix parts, 11 ... Pull bar, 12 ... Fuse support, 13 ... Transmission lever, 21
... Polyester premix molded product, 22 ... Protective layer.

Claims (1)

[Claims] 1. A polyester premix molded product containing calcium carbonate powder as a filler, the surface of which is coated with a protective layer made of an epoxy resin coating material for preventing permeation of an oxidizing substance into the molded product. Polyester premix parts for high-voltage equipment characterized by