JP5044345B2 - Switchgear - Google Patents

Description

The present invention relates to a switchgear such as a circuit breaker having an insulator suitable for supporting a high voltage conductor in a high voltage device.

  In a high voltage device, a high voltage conductor to which a high voltage is applied is supported by an insulator and insulated from a ground potential. An electric field determined by the applied voltage, the shape and material of the insulator, and the electrode arrangement around the insulator is applied to the insulator.

  In recent years, as shown in FIG. 7, a closed type switchgear having a structure in which a high voltage conductor 4 supported by an insulator 3 is arranged in a sealed container 2 filled with an insulating gas 1 and grounded is often used. It is supposed to be. Many such sealed switchgears are applied to AC voltage transmission systems.

In the hermetic switchgear, when the circuit is opened to cut off the current, cracked gas 7 is generated by the arc 6 generated between the electrodes 5a and 5b. In the case of a circuit breaker using SF ₆ as the insulating gas 1, a very active decomposition gas such as SF ₄ is generated. The decomposition gas 7 reaching the insulator 3 deteriorates the resin constituting the insulator 3 or deteriorates the interface between the filler and the resin contained in the insulator 3 to improve the insulation performance and mechanical properties of the insulator 3. There is a risk of degrading performance.

  In order to prevent this, the surface of the insulator 3 may be provided with a decomposition-resistant gas coating. Conventional anti-decomposition gas coating is a structure in which a resin with high anti-decomposition gas performance is thickly applied and carefully applied so that pinholes and non-uniformity in film thickness do not occur, resulting in an increase in material and work costs. It is a factor.

  Generally, a closed type switchgear provided in an AC voltage transmission system is designed and manufactured in consideration of an electric field distribution with respect to the AC voltage, but a DC voltage is also applied to a closed type switchgear provided in an AC voltage transmission system. There is. In particular, after the opening / closing operation of the switchgear, the DC voltage remains in the high voltage circuit, and the DC voltage may be applied to the AC voltage high voltage device for a long time.

  That is, as shown in FIG. 8, when the disconnector 22 adjacent to the open circuit breaker 21 is opened, a residual DC voltage is applied to the circuit 23 between the disconnector 22 and the circuit breaker 21 as shown in FIG. 24 occurs. Especially in gas-insulated high-voltage equipment, the decay time of the residual DC voltage is long due to the excellent insulating performance of the insulating gas. As a result, even in equipment for AC voltage, DC voltage is applied to the insulator for a long time. As a result, the DC withstand voltage characteristics of the insulator may be important. In the gas-insulated hermetic switchgear, further downsizing is aimed at by reducing the cost by reducing the rationalization of the insulation configuration or integrating three phases. For this reason, the operating electric field tends to increase, and as a result, the DC electric field due to the residual DC voltage also increases, and the importance of the insulation reliability for the DC withstand voltage of the insulator tends to increase.

  In general, the electric field distribution of an insulator when a DC voltage is applied is different from that when an AC voltage is applied. If the insulation configuration is considered in consideration of only the AC electric field distribution, an unexpected electric field concentration portion may occur in the DC electric field distribution generated by the residual DC voltage. In particular, charges are likely to accumulate due to residual DC voltage at the interface between insulators having different resistivity, and the accumulated charges tend to cause local electric field concentration.

  For this reason, when the operating electric field is increased, it is necessary to consider electric field distribution with respect to DC voltage even in an AC voltage device, and it is necessary to have a configuration in which charges are difficult to accumulate. Considering not only the electric field distribution against AC voltage but also the electric field distribution against DC voltage in the insulation design of AC voltage equipment makes it difficult to reduce the insulation size, and is an obstacle to the rationalization of the insulation configuration and the promotion of three-phase integration. Is likely.

  As described above, in the circuit in the vicinity of the circuit breaker, it is necessary to prevent the deterioration of the insulator and the charge accumulation due to the decomposition gas. Conventionally, preventing this has hindered the reduction of the insulation size and the cost.

Recently, diamond-like carbon (DLC) films have been applied to various fields. DLC film generally has high hardness, excellent wear resistance, smooth flat surface, small friction coefficient, excellent releasability, excellent chemical resistance and corrosion resistance, near red It has features such as excellent outer permeability and excellent insulating properties. Techniques for applying a DLC film to plastic have begun to be put into practical use, and an invention for giving a high gas barrier property to a plastic (Patent Document 1) and an invention for continuously DLC coating a plastic tape (Patent Document 2) have been made. Furthermore, the invention of the DLC coating to the metal using corrosion resistance and plasma resistance (patent documents 3 and 4) has also been made.
JP 2006-82814 A JP 2006-70238 A JP 2004-307894 A JP 2004-214370 A

  In order to improve the insulation reliability of insulators that are likely to be exposed to the decomposed gas in the same unit as the circuit breaker of a closed switchgear, the characteristics of the gas barrier performance and corrosion resistance of the DLC film are excellent. There are the following problems.

That is, first, the volume resistivity of the realized DLC film is generally 10 ⁹ to 10 ¹⁴ Ωcm. However, the DLC film having an appropriately selected volume resistivity can be effectively applied to an insulator for high voltage equipment. It is a membrane. During normal operation, commercial AC voltage is applied to the insulator for high voltage equipment. When the volume resistivity of the DLC film is too low, the withstand voltage performance of the DLC film is lowered, and it becomes difficult to ensure insulation reliability at a commercial operating voltage. It is known that the volume resistivity of the DLC film varies depending on the substrate bias voltage that affects the ion collision energy during film formation. By changing the bias voltage, DLC films having various volume resistivity can be formed.

  Next, the general thickness of the DLC film is as thin as about 10 μm. On the other hand, the surface roughness of the insulator for electric power equipment may be several tens of μm or more depending on the case. When the surface roughness of the insulator for high voltage equipment is rough, There may be a case where a portion without a film is generated and it is difficult to obtain a sufficient gas barrier effect.

  In addition, since the DLC film has a high hardness, it tends to crack due to stress. In contrast, high-voltage devices are likely to change in temperature due to fluctuations in energization current and changes in outside air temperature. In general, since the thermal expansion coefficient of an insulator is larger than that of a DLC film, stress is easily generated at the interface between the insulator and the DLC film as a base material due to temperature change, and the DLC film is likely to crack. A sufficient gas barrier performance cannot be expected for a cracked DLC film.

The present invention has been made to solve the above-described problems, and has an insulator suitable for high-voltage equipment, which has high resistance to cracked gas generated by an arc and can attenuate residual DC voltage in a short time. An object is to provide a highly reliable switchgear.

In order to solve the above problems, the switchgear according to the present invention is a switchgear configured to support a high-voltage conductor with an insulator for high-voltage equipment in an airtight container in which an insulating gas is sealed. The device insulator is provided with a diamond-like carbon film having a volume resistivity of 10 ¹⁴ to 10 ¹⁵ Ωcm, which is the same as that of the base material of the insulator, on the surface of the base material of the high-voltage device insulator , It is characterized by increasing the resistance against the decomposition gas generated by the arc and reducing the charge accumulated at the interface between the insulating base material and the diamond-like carbon film when a direct current is applied .

ADVANTAGE OF THE INVENTION According to this invention, the tolerance with respect to the decomposition gas produced by an arc is high, and it can attenuate a residual DC voltage in a short time, and can provide the reliable switchgear which has the insulator suitable for a high voltage apparatus. .

  Hereinafter, five embodiments of the present invention will be specifically described with reference to the drawings. The same members as those of the conventional one shown in FIG.

(First embodiment)
FIG. 1 is a cross-sectional view showing a configuration of an insulator and a switchgear according to the first embodiment of the present invention. That is, this embodiment is a hermetic switchgear in which the high voltage conductor 4 is supported in the hermetic container 2 by the high voltage device insulator 8 and the insulating gas 1 is sealed. The DLC film 10 having a volume resistivity adjusted to the same level as that of the GFRP base material 9 is provided on the surface of the GFRP (glass fiber reinforced resin) base material 9.

  GFRP, which is manufactured by impregnating a glass fiber aggregate with a resin such as an epoxy resin and has excellent mechanical characteristics, may be used as an insulator for high-voltage devices in a hermetic switchgear. However, when used in an environment where the cracked gas 7 is present, the glass fibers constituting the GFRP substrate 9 are likely to be corroded by the cracked gas 7 and therefore need to be used in combination with a cracked gas coating.

  Decomposition-resistant gas coating and GFRP generally differ in volume resistivity. As shown in FIG. 2, generally, when a DC voltage is applied in a state where insulators 11 and 12 having different volume resistivity are overlapped, charges 14 are accumulated at the interface 13. The accumulated electric charge 14 has the effect of locally increasing the electric field when a lightning impulse voltage is applied, etc., and therefore the withstand voltage performance of the insulator is lowered. In the insulator 8 for a high voltage device in which the DLC film 10 is provided on the surface of the GFRP base material 9, when the volume resistivity of the insulator GFRP base material 9 and the DLC film 10 is approximately the same, a DC voltage is applied. In this case, it is possible to reduce charge accumulation at the interface between the GFRP base material 9 and the DLC film 10.

When an insulator for high voltage equipment is exposed to a commercial operating voltage, the insulation performance generally deteriorates rapidly when the volume resistivity of the surface layer of the insulator is lower than 10 ¹³ Ωcm. The volume resistivity of GFRP impregnated with glass fiber is often about 10 ¹⁵ Ωcm. For this reason, the DLC film 10 adjusted to have a volume resistivity of about 10 ¹⁴ to 10 ¹⁵ Ωcm by adjusting the substrate bias voltage and the like during film formation is provided on the surface of the GFRP substrate 9 and applied with direct current. Occasionally, the accumulation of space charge at the interface between the DLC film 10 and the GFRP base material 9 is suppressed to prevent the insulation performance from being reduced with respect to the commercial voltage. Since the volume resistivity of the DLC film 10 and the GFRP base material 9 are close to each other, it is possible to suppress the charge accumulated at these interfaces when DC is applied.

  As a result, the decomposition gas performance is improved, and at the same time, the insulation reliability can be improved even for the lightning impulse voltage that may be applied after the residual DC voltage is applied. Therefore, according to the present embodiment, an insulating material that has high insulation reliability with respect to residual DC voltage and has high mechanical strength and is suitable for high-voltage equipment even under use conditions where cracked gas exists, and a highly reliable switchgear. Can be provided.

(Second Embodiment)
As shown in FIG. 3, the second embodiment of the present invention is a hermetically opened / closed structure in which a high-voltage conductor 4 is supported by an insulator 8a for high-voltage equipment and an insulating gas 1 is enclosed in the hermetic container 2. In the apparatus, the insulator 8a for high-voltage equipment is formed on the surface of the cast product base material 15 whose volume resistivity is adjusted, and the DLC film adjusted so that the volume resistivity is approximately the same as that of the cast product base material 15 10 is provided.

Note: An epoxy resin or other resin is cast into an admixture of silica, alumina, or other filler that has a low coefficient of thermal expansion and improved mechanical strength, or a liquid polyamide resin or liquid polysulfide polymer. Since the shaped substrate 15 is excellent in heat resistance and mechanical strength, it is often used in a closed type switchgear. However, in an environment where the cracked gas 7 is present, the filler itself or the interface between the filler and the epoxy resin may be corroded by the cracked gas, and the mechanical strength and the insulation resistance of the surface layer may be greatly reduced. It is known that when the insulator is exposed to a commercial operating voltage, the insulation performance decreases rapidly when the volume resistivity of the surface layer is lower than 10 ¹³ Ωcm.

In general, it is known that in a cast insulator using a filled epoxy resin, the volume resistivity can be changed by adjusting and imparting an imparting agent such as a liquid polyamide resin or a liquid polysulfide polymer, such as 10 to 20 phr. By using these, it is possible to obtain a cast article base material 15 whose volume resistivity is adjusted to about 10 ¹⁵ Ωcm.

The insulator 8a for high voltage equipment of the present embodiment has a volume resistivity adjusted by adjusting a substrate bias voltage at the time of film formation on the surface of the cast article substrate 15 having the volume resistivity adjusted in this way. DLC film 10 adjusted to be about 10 ¹⁴ to 10 ¹⁵ Ωcm is provided to suppress the accumulation of space charges at the interface between DLC film 10 and cast article base 15 when DC is applied, and to insulate against commercial voltage Prevent performance degradation. Since the volume resistivity of the DLC film 10 and the cast article base material 15 is close, the charge accumulated at the interface when DC is applied can be kept small.

  As a result, the decomposition gas performance can be improved, and at the same time, the insulation reliability can be improved even for the lightning impulse voltage that may be applied after the residual DC voltage is applied. Therefore, according to the present embodiment, an insulating material suitable for high-voltage equipment and a highly reliable switchgear are provided that has high insulation reliability and high mechanical strength against residual DC voltage even under the use conditions where cracked gas exists. can do.

(Third embodiment)
As shown in FIG. 4, the third embodiment of the present invention is a hermetically sealed opening / closing formed by supporting a high-voltage conductor 4 with an insulator 8b for high-voltage equipment and enclosing an insulating gas 1 in a sealed container 2. In the apparatus, the insulator 8b for high-voltage equipment forms a coating film 16 such as an epoxy resin in which the imparting agent is adjusted so that the volume resistivity is about 10 ¹⁴ to 10 ¹⁵ Ωcm on the surface of the GFRP base material 9. The DLC film 10 adjusted so that the volume resistivity is 10 ¹⁴ Ωcm is provided thereon.

An insulator made of GFRP, which is manufactured by impregnating a glass fiber aggregate with a resin and has excellent mechanical properties, is excellent in mechanical strength and may be used in a hermetic switchgear. However, since glass fiber is easily corroded by cracked gas, it must be used in combination with a cracked gas coating when used in an environment where cracked gas exists. When the insulator for high voltage equipment is exposed to a commercial operating voltage, it is known that the insulation performance deteriorates rapidly when the volume resistivity of the surface layer of the insulator for high voltage equipment is lower than 10 ¹³ Ωcm.

In the present embodiment, in consideration of this, in order to attenuate the residual DC voltage in a short time and reduce the time during which the DC voltage is applied to the insulator for high voltage equipment, the influence on the insulation performance is eliminated. A volume resistivity of 10 ¹⁴ to 10 ¹⁵ Ωcm is obtained by adjusting and applying an insulator such as a liquid polyamide resin or a liquid polysulfide polymer to the surface of the GFRP base material 9 for 10 to 20 phr for the insulator 8b for voltage equipment. A coating film 16 such as an epoxy resin adjusted as described above is formed.

  As the resin coating film 16 with the volume resistivity adjusted becomes thicker, the overall resistance value decreases, and the DC voltage remaining in the main circuit can be leaked and attenuated in a shorter time. Can be reduced.

  In general, it is difficult to increase the thickness of the DLC film 10 to several μm or more. However, in the case of the configuration of the present embodiment, the residual DC voltage is not attenuated through the DLC film 10, so the thickness of the DLC film 10 is thin. There is no problem, and the resin coating film 16 can be thickened relatively easily. Further, since the surface roughness of the resin coating 16 applied to the surface of the GFRP substrate 9 is generally as small as several μm or less, it is easy to form a thin DLC film without any pinholes, which is a weak point on the gas block. Can be prevented. Furthermore, since the volume resistivity of the DLC film 10, the resin coating film 16, and the GFRP base material 9 is close, it is possible to suppress the charge accumulated at each interface when DC is applied.

  As a result, the gas blocking property of the DLC film 10 is used to improve the decomposition gas performance, and at the same time, the insulation reliability against lightning impulse voltage that may be applied after applying the residual DC voltage is improved. Can do. Therefore, according to the present embodiment, an insulating material suitable for high-voltage equipment and a highly reliable switchgear are provided that has high insulation reliability and high mechanical strength against residual DC voltage even under the use conditions where cracked gas exists. can do.

(Fourth embodiment)
As shown in FIG. 5, the fourth embodiment of the present invention is a hermetically opened / closed structure in which a high-voltage conductor 4 is supported by an insulator 8c for high-voltage equipment in an airtight container 2 and an insulating gas 1 is enclosed. In the apparatus, the insulator 8c for high-voltage equipment is formed by applying an elastic resin 18 such as an elastomer to the surface of the insulator 17 such as GFRP or cast product as a base material, and then biasing the base material during film formation. In this configuration, the DLC film 10 is adjusted so that the volume resistivity is about 10 ¹⁴ Ωcm by adjusting the voltage or the like.

  The DLC film has gas barrier properties and corrosion resistance, but has high hardness and is likely to crack. In contrast, high-voltage devices are likely to change in temperature due to fluctuations in energization current and changes in outside air temperature. The thermal expansion coefficient of a general insulator is larger than that of the DLC film, and stress is generated at the interface between the insulator 17 such as GFRP as a base material and cast products and the DLC film 10 due to temperature change, and the DLC film 10 is cracked. Cheap. It is difficult to expect the gas barrier performance of the cracked DLC film 10.

In the present embodiment, by providing an elastic resin 15 layer made of an elastomer or the like between the insulator 17 and the DLC film 10, the stress generated at the interface between the insulator 17 such as GFRP and the DLC film 10 can be reduced. The crack of the DLC film 10 can be prevented. Furthermore, it is known that when the insulation for high-voltage equipment is exposed to commercial operating voltage, the insulation performance decreases rapidly when the volume resistivity of the surface layer is lower than 10 ¹³ Ωcm. The volume resistivity of the layer made of the resin 18 can be adjusted to about 10 ¹⁴ Ωcm by, for example, applying an imparting agent such as a liquid polyamide resin or a liquid polysulfide polymer for 10 to 20 phr. As the elastic resin 18 whose volume resistivity is adjusted is thicker, the resistance value of the high-voltage device insulator 8c is reduced, and the DC voltage remaining in the main circuit can be leaked and attenuated in a shorter time. It is possible to suppress the accumulation of charges due to the influence of the voltage.

  In the present embodiment, since the residual DC voltage is not attenuated through the DLC film 10, there is no problem even if the thickness of the DLC film 10 is thin, and the elastic resin 18 can be thickened relatively easily. In addition, since the surface roughness of the elastic resin 18 composed of an elastomer or the like is generally as small as several μm or less, even the thin DLC film 10 is easy to form without pinholes or discontinuities, and weak points on the gas block are hardly generated. . Furthermore, since the volume resistivity of the DLC film 10, the elastic resin 18, and the insulator 17 is close, it is possible to suppress the charge accumulated at each interface when DC is applied.

  As a result, the decomposition gas performance can be improved, and at the same time, the insulation reliability can be improved even for the lightning impulse voltage that may be applied after the residual DC voltage is applied. Therefore, according to the present embodiment, an insulating material suitable for high-voltage equipment and a highly reliable switchgear that has high insulation reliability and high mechanical strength with respect to residual DC voltage even under use conditions where cracked gas exists. Can be provided.

(Fifth embodiment)
In the fifth embodiment of the present invention, as shown in FIG. 6, a hermetic opening and closing formed by supporting a high voltage conductor 4 with an insulator 8 d for high voltage equipment and enclosing an insulating gas 1 in a hermetic container 2. In the apparatus, the insulator 8d for high-voltage equipment is obtained by winding a DLC coated tape 19 in which a DLC film is previously provided on a plastic tape such as PET (polyethylene terephthalate) on the surface of the insulator 17 such as GFRP or cast product. Thereafter, the resin coating film 16 is formed on the surface by impregnating with an epoxy resin or the like adjusted to have a volume resistivity of about 10 ¹⁴ Ωcm.

  The DLC film has gas barrier properties and corrosion resistance, but has high hardness and is likely to crack. In addition, coating a DLC film on an insulator having a large surface area without a gap such as a pinhole requires a large processing time and cost.

  On the other hand, forming a DLC film uniformly in a limited width like a plastic tape can be carried out at a lower cost. When a plastic tape provided with a DLC film is wound around an insulator, the structure can be made close to that provided with a DLC film directly on the insulator, and gas blocking performance can be expected, but the DLC film has a small coefficient of friction. Because of this, the tape tends to slip. If the tape is displaced, it is difficult to expect gas blocking properties.

  In the present embodiment, the DLC coated tape 19 is displaced by winding the DLC coated tape 19 around the insulator 17 such as a GFRP or a cast product and then impregnating the DLC coated tape 19 with an epoxy resin or the like having a controlled resistivity. Can be prevented.

When the insulator 8d for high voltage equipment is exposed to a commercial operating voltage, the insulation performance decreases rapidly if the volume resistivity of the surface layer is lower than 10 ¹³ Ωcm. Can be adjusted to about 10 ¹⁴ Ωcm by applying an imparting agent such as a liquid polyamide resin or a liquid polysulfide polymer for 10 to 20 phr. As the coating film 16 such as an epoxy resin whose volume resistivity is adjusted is thicker, the resistance value of the insulator 8d for high voltage equipment is lowered, and the DC voltage remaining in the main circuit can be attenuated in a shorter time, It is possible to reduce the occurrence of charge accumulation due to the influence of the DC voltage.

  In the present embodiment, since the residual DC voltage is not attenuated through the DLC film, the DLC film provided on the DLD coated tape 18 may be thin. Further, since the volume resistivity of the DLC film, the impregnating resin (epoxy), and the insulator 17 such as GFRP and cast products are close to each other, the charge accumulated at the interface between the DLC film and the impregnating resin (epoxy) is reduced when DC is applied. Can be suppressed.

  As a result, the decomposition gas performance can be improved, and at the same time, the insulation reliability can be improved even for the lightning impulse voltage that may be applied after the residual DC voltage is applied. In this way, according to the present embodiment, an insulating material suitable for high-voltage equipment and a highly reliable switchgear are provided that have high insulation reliability against residual DC voltage even under use conditions where cracked gas exists. be able to.

Sectional drawing which shows the structure of the insulator and switchgear of the 1st Embodiment of this invention. The figure which shows the electric charge accumulate | stored in the interface of the insulator from which volume resistivity differs, and demonstrates the effect | action of the 1st Embodiment of this invention. Sectional drawing which shows the structure of the insulator and switchgear of the 2nd Embodiment of this invention. The structure of the insulator and switchgear of the 3rd Embodiment of this invention is shown, (a) is sectional drawing, (b) is an enlarged view of the (b) part of (a). The structure of the insulator and switchgear of the 4th Embodiment of this invention is shown, (a) is sectional drawing, (b) is an enlarged view of the (b) part of (a). Sectional drawing which shows the structure of the insulator and switchgear of the 5th Embodiment of this invention. Sectional drawing which shows the structure of the conventional closed type switchgear. The circuit diagram of the conventional sealed switchgear. The wave form diagram explaining generation | occurrence | production of the residual DC voltage in the conventional sealed switchgear.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 ... Insulating gas, 2 ... Sealed container, 3 ... Insulator, 4 ... High voltage conductor, 5a, 5b ... Electrode, 6 ... Arc, 7 ... Decomposed gas, 8, 8a, 8b, 8c, 8d ... High voltage apparatus Insulator, 9 ... GFRP substrate, 10 ... DLC film, 11, 12 ... insulator, 13 ... interface, 14 ... charge, 15 ... cast substrate, 16 ... resin coating, 17 ... GFRP, cast 18 ... elastic resin, 19 ... DLC coated tape, 21 ... open circuit breaker, 22 ... open operation disconnector, 23 ... circuit between disconnector and circuit breaker, 24 ... residual DC voltage.

Claims (5)

In a switchgear configured to support a high-voltage conductor with an insulator for high-voltage equipment in a sealed container filled with an insulating gas,
The insulator for high-voltage equipment is a diamond-like carbon film having a volume resistivity of 10 ¹⁴ to 10 ¹⁵ Ωcm, which is the same as that of the base material of the insulator, with respect to the surface of the base material of the insulator for high-voltage equipment. A switchgear characterized in that it is provided with a high resistance to a cracked gas generated by an arc and reduces charges accumulated at the interface between the insulating base material and the diamond-like carbon film when a direct current is applied . The switchgear according to claim 1, wherein the base material of the insulator for high voltage equipment is made of GFRP. 2. The switchgear according to claim 1, wherein the base material of the insulator for high-voltage equipment is a resin-cast product containing a filler. The resin coating or elastic resin layer having the same volume resistivity as that of the base is provided between the base of the insulator for the high voltage device and the diamond-like carbon film. The switchgear according to any one of 1 to 3. The diamond-like carbon film is formed by winding a tape formed by applying diamond-like carbon to a plastic film. After the tape is wound, the diamond-like carbon film is interposed between the base material of the high-voltage device insulator and the diamond-like carbon film. The switchgear according to any one of claims 1 to 3, wherein a resin having a volume resistivity equivalent to that of the substrate is impregnated.

Images