Insulating oil composition and oil-filled electric device

Abstract

The present invention provides electrical insulating oil having high heat dissipation characteristics and suitable handling properties under the Fire Service Act. An insulating oil composition, which is biodegradable electrical insulating oil derived from plants, comprising: a natural ester mainly containing triglyceride; and first insulating oil selected from a plant-derived ester and electrical insulating oil composed of linear alkylbenzene.

Description

Insulating oil composition and oil-filled electrical device

[0001] The present invention relates to an insulating oil composition and an oil-filled electrical device.

[0002] Electrical insulating oils are used as insulating materials for oil-filled electrical devices. In recent years, from the viewpoint of environmental consideration, the use of electrical insulating oils containing vegetable oils as biodegradable electrical insulating oils has been considered. Under these circumstances, Patent Document 1 discloses an electrical insulating oil containing vegetable oil and alkylbenzene as an electrical insulating oil containing vegetable oil.

[0003] Japanese Patent Publication No. 2010-287788

[0004] However, vegetable oils are characterized by high viscosity and poor heat dissipation properties. Therefore, when vegetable oils are used in electrical equipment, the number of heat sinks required for heat dissipation increases, resulting in an increase in the size of the electrical equipment. Furthermore, when vegetable oils are mixed with other oils, the flash point and combustion point decrease, and restrictions on the handling of electrical insulating oils may be imposed under the Fire Service Act. From these perspectives, there is room for further study of the technology described in Patent Document 1.

[0005] In view of the current situation, one aspect of the present invention aims to provide an electrical insulating oil that has high heat dissipation properties and is easy to handle under the Fire Service Act.

[0006] In order to solve the above-mentioned problems, an insulating oil composition according to one embodiment of the present invention comprises a first insulating oil selected from a biodegradable electrical insulating oil derived from plants, which is a natural ester mainly containing triglycerides, a biodegradable electrical insulating oil derived from plant oils, which is a natural ester mainly containing triglycerides, a plant-derived ester mainly containing monoglycerides, which is a biodegradable electrical insulating oil containing an ester bond formed by a chemical reaction between a fatty acid derived from plant oils and an alcohol, or an electrical insulating oil made of linear alkylbenzene, and the content of the first insulating oil is 1 to 15% by weight based on the total weight of the insulating oil composition.

[0007] In order to solve the above-mentioned problems, an oil-filled electrical device according to one aspect of the present invention is an oil-filled electrical device that uses the insulating oil composition described above.

[0008] The object of the present invention is to provide an electrical insulating oil that has high heat dissipation properties and is easy to handle in accordance with the Fire Service Act.

[0009] 1 is a graph showing the relationship between the mixing ratio of palm fatty acid ester oil and kinematic viscosity in the insulating oil compositions of Examples 1 and 2. FIG. 2 is a graph showing the relationship between the mixing ratio of mineral oil in the insulating oil compositions of Comparative Examples 1 and 2 and the kinematic viscosity of the insulating oil compositions. FIG. 3 is a graph showing the relationship between the mixing ratio of first insulating oil in the insulating oil compositions of Examples 1, 2, and Comparative Examples 1 and 2 and the flash points of the insulating oil compositions. FIG. 4 is a graph showing the relationship between the mixing ratio of palm fatty acid ester oil in the insulating oil compositions of Examples 1 and 2 and the fire points of the insulating oil compositions. FIG. 5 is a graph showing the relationship between the mixing ratio of mineral oil in the insulating oil compositions of Comparative Examples 1 and 2 and the fire points of the insulating oil compositions.

[0010] [Embodiment 1] An insulating oil composition according to one embodiment of the present invention will be described below. Note that the following description is intended to provide a better understanding of the gist of the invention, and does not limit the present invention unless otherwise specified.

[0011] The insulating oil composition according to this embodiment contains a first insulating oil selected from a natural ester containing primarily triglycerides, a plant-derived ester containing primarily monoglycerides, or an electrical insulating oil comprising a linear alkylbenzene. The content of the first insulating oil is 1% by weight to 15% by weight based on the total weight of the insulating oil composition. In this specification, the term "A to B" representing a numerical range refers to a range that includes A and B, i.e., "A or more and B or less."

[0012] Natural esters have a high viscosity, and when applied to oil-filled electrical equipment, their heat dissipation characteristics can be an issue. By including a first insulating oil in addition to a natural ester, an insulating oil composition with a lower viscosity than that of a natural ester can be realized. Furthermore, by limiting the content of the first insulating oil, a suitable flash point and combustion point can be achieved, and an insulating oil composition that is easy to handle under the Fire Service Act can be realized.

[0013] The insulating oil composition preferably has a flash point of 250°C or higher and a fire point of 300°C or higher. Insulating oil compositions with flash points within these ranges are not classified as hazardous materials under Article 2, Paragraph 7 of the Fire Service Act, making them easier to handle under the Fire Service Act. In particular, when installing oil-filled electrical equipment using insulating oil compositions whose flash point and fire point both fall within the above-mentioned ranges, the installation of large-scale fire extinguishing equipment is permitted instead of special fire extinguishing equipment (Fire Prevention Notification No. 205, dated March 30, 2023). For this reason, insulating oil compositions that satisfy these flash points and fire points are preferred from the standpoint of ease of handling.

[0014] In this specification, flash point refers to the lowest temperature at which a sample ignites. In this specification, fire point refers to the lowest temperature of a sample at which, when an ignition source is brought close to the sample vapor under specified conditions, the sample vapor emits a flash and burns instantaneously, and continues to burn for 5 seconds or more. In this specification, flash point and fire point are measured by the open cup flash point test method. Flash point and fire point can be measured by JIS K 2265, Section 7 (Cleveland open cup flash point test method).

[0015] In this specification, kinematic viscosity is used as an index of viscosity. Kinematic viscosity can be determined by the kinematic viscosity test method specified in JIS K 2283. Kinematic viscosity can be determined by multiplying the distillation time by the viscometer constant of the viscometer. In this specification, the viscometer is a glass capillary viscometer. Kinematic viscosity is calculated by the following formula (1):

[0016] v = Ct (1) where v is the kinematic viscosity (mm ２ / s), and C is the viscometer constant (mm ２ / s), and t is the time (s) required for flow.

[0017] (Natural Ester) Natural ester is a biodegradable electrical insulating oil derived from plants and mainly contains triglycerides. In this specification, "derived from plants" means derived from plant seeds and other suitable biological materials. In this specification, "A mainly contains component B" means that A contains component B as a main component, for example, 50% or more of A is component B.

[0018] Natural esters are preferred from the viewpoint of being suitable for electrical insulation and easy to handle under the Fire Service Act due to their high flash point and combustion point. Furthermore, natural esters are also preferred from the viewpoint of environmental considerations, as they are biodegradable electrical insulating oils and have low fish toxicity.

[0019] The kinematic viscosity of the natural ester at 40°C is not particularly limited, but is preferably 50 mm ２ The natural ester having a kinematic viscosity in this range corresponds to the natural ester specified in JIS C 2390-2.

[0020] The content of the natural ester contained in the insulating oil composition is not particularly limited and may be determined appropriately within a range that achieves the desired physical properties. For example, the content of the natural ester may be 80% by weight to 99% by weight, based on the total amount of the insulating oil composition. From the viewpoint of achieving a high flash point and fire point in the insulating oil composition, the content of the natural ester may be 85% by weight or more, 88% by weight or more, or 90% by weight or more, based on the total amount of the insulating oil composition. On the other hand, from the viewpoint of achieving an insulating oil composition with a certain viscosity, the content of the natural ester may be 97% or less, 95% or less, or 92% or less, based on the total amount of the insulating oil composition.

[0021] The flash point and combustion point of the natural ester are not particularly limited. For example, from the viewpoint of ensuring that the flash point of the insulating oil composition falls within a suitable range, the flash point of the natural ester is preferably 275°C or higher, more preferably 280°C or higher, and even more preferably 300°C or higher. Furthermore, from the viewpoint of ensuring that the combustion point of the insulating oil composition falls within a suitable range, the combustion point of the natural ester is preferably 310°C or higher, more preferably 330°C or higher, and even more preferably 350°C or higher.

[0022] The plant from which the natural ester is derived is not particularly limited as long as it can achieve the above-mentioned physical properties. The natural ester may be selected from, for example, rapeseed oil, soybean oil, corn oil, perilla oil, peanut oil, tung oil, cottonseed oil, linseed oil, castor oil, coconut oil, palm oil, olive oil, sesame oil, rice bran oil, sunflower oil, safflower oil, and camellia oil. In particular, the natural ester is preferably selected from rapeseed oil, soybean oil, and sunflower oil.

[0023] The natural ester may be a natural ester (vegetable oil) as specified in JIS C 2390-2.

[0024] (First insulating oil) The first insulating oil is selected from plant-derived esters or linear alkylbenzenes. Plant-derived esters mainly contain monoglycerides containing ester bonds formed by a chemical reaction between fatty acids derived from plant oils and alcohols. These oils have lower kinematic viscosities than natural esters, and therefore can reduce the kinematic viscosity of the natural esters. Furthermore, plant-derived esters and linear alkylbenzenes are biodegradable insulating oils, making them preferable from an environmental perspective.

[0025] The first insulating oil has a kinematic viscosity of 13 mm at 40°C. ２ / s or less, and ２ / s or less is more preferable, and 8 mm ２ / s or less is more preferable. By ensuring that the kinematic viscosity does not exceed the upper limit, the kinematic viscosity of the insulating oil composition can be reduced, thereby achieving favorable heat dissipation characteristics. There is no particular restriction on the lower limit of the kinematic viscosity.

[0026] The following describes the case where the first insulating oil is a plant-derived ester. The content of the plant-derived ester is preferably 3 wt % to 15 wt % based on the total amount of the insulating oil composition. The content of the plant-derived ester is preferably 4.5 wt % or more, and more preferably 5 wt % or more, based on the total amount of the insulating oil composition. By satisfying this range, the effect of reducing the kinematic viscosity of the insulating oil composition by the plant-derived ester can be more suitably obtained. On the other hand, the content of the plant-derived ester is preferably 13 wt % or less, and more preferably 10 wt % or less, based on the total amount of the insulating oil composition. By satisfying this range, the flash point and fire point of the insulating oil composition can be set within suitable ranges. It is preferable that the content of the plant-derived ester be within the upper and lower limit values ​​from the viewpoints of suitably reducing the kinematic viscosity and setting the flash point and fire point within suitable ranges.

[0027] The kinematic viscosity of the plant-derived ester at 40°C is 13 mm from the viewpoint of suitably reducing the kinematic viscosity of the insulating oil composition. ２ / s or less, and ２ / s or less is more preferable, and 8 mm ２ It is more preferable that the ratio is 1 / s or less.

[0028] The flash point and combustion point of the plant-derived ester are not particularly limited. For example, from the viewpoint of ensuring that the insulating oil composition has a flash point within a suitable range, the flash point of the plant-derived ester is preferably 150°C or higher, and more preferably 170°C or higher. Furthermore, from the viewpoint of ensuring that the insulating oil composition has a combustion point within a suitable range, the combustion point of the plant-derived ester is preferably 180°C or higher, and more preferably 200°C or higher.

[0029] The plant-derived ester is not particularly limited. Examples of vegetable oils from which the plant-derived ester is derived include rapeseed, soybean, corn, perilla, peanut, paulownia, cottonseed, linseed, castor, coconut, oil palm, olive, sesame, rice, sunflower, safflower, and camellia. From the viewpoints of reducing the viscosity of the insulating oil composition while keeping the flash point and combustion point within suitable ranges, palm fatty acid ester oil derived from the pulp of oil palm and rapeseed ester oil are preferred as the plant-derived ester.

[0030] The plant-derived ester may be a plant-derived ester specified in JIS C 2390-3.

[0031] The following describes the case where the first insulating oil is a linear alkylbenzene. The linear alkylbenzene content is preferably 1 to 3% by weight based on the total weight of the insulating oil composition. By having the linear alkylbenzene content in this range, the viscosity of the insulating oil composition can be suitably reduced, and the flash point and fire point can be kept within suitable ranges.

[0032] Linear alkylbenzene has a kinematic viscosity of 5 mm at 40°C. ２ It is preferable that the viscosity is less than 1 / s. Such low-viscosity linear alkylbenzene is specified as type 2, number 3 alkylbenzene in JIS C 2320. When the linear alkylbenzene has a low viscosity, the viscosity of the insulating oil composition can be more suitably reduced.

[0033] (Other) The insulating oil composition according to this embodiment may be used for an oil-filled electrical device. The insulating oil composition has insulating properties and is excellent in heat dissipation characteristics and handling properties, and therefore can be suitably used as an insulating material. In this specification, the oil-filled electrical device is not particularly limited, but examples thereof include an oil-filled transformer, an oil-filled voltage converter, an oil-filled reactor, an oil-filled capacitor, an oil-filled cable, and an oil-filled circuit breaker.

[0034] The kinematic viscosity of the electrical oil composition according to this embodiment is lower than that of the natural ester. Although not particularly limited, the kinematic viscosity of the electrical oil composition is preferably at least 5% lower, and more preferably at least 8% lower, than that of the natural ester.

[0035] The electrical oil composition may contain additives and other components for the purpose of improving any of the properties described above, as long as they do not substantially affect the properties. Examples of additives include antioxidants, flow charge inhibitors, and pour point depressants.

[0036] The insulating oil composition according to this embodiment includes a natural oil composition and a first insulating oil. This configuration allows for a highly biodegradable insulating oil composition. Such an effect also contributes to the achievement of, for example, Goal 12 of the Sustainable Development Goals (SDGs) advocated by the United Nations, "Ensure sustainable consumption and production patterns."

[0037] [Embodiment 2] An electrical device according to one embodiment of the present invention will be described below. The electrical device according to this embodiment is an oil-filled electrical device that uses the insulating oil composition described above. Such imported electrical devices are preferred from the perspective of miniaturization due to the excellent heat dissipation characteristics of the insulating oil composition. Furthermore, the insulating oil composition has a high flash point and combustion point, making it preferred from the perspective of ease of handling under the Fire Service Act.

[0038] The oil-filled electrical equipment is not particularly limited, and may be an oil-filled transformer, an oil-filled voltage converter, an oil-filled reactor, an oil-filled capacitor, an oil-filled cable, an oil-filled circuit breaker, etc. In particular, the oil-filled electrical equipment may be an oil-filled transformer, an oil-filled voltage converter, or an oil-filled reactor.

[0039] The present invention is not limited to the above-described embodiments, and various modifications are possible within the scope of the claims. Embodiments obtained by appropriately combining the technical means disclosed in different embodiments are also included in the technical scope of the present invention.

[0040] [Summary] The insulating oil composition according to Aspect 1 of the present invention comprises a first insulating oil selected from a plant-derived biodegradable electrical insulating oil that is a natural ester mainly containing triglycerides, a plant-derived biodegradable electrical insulating oil that contains an ester bond formed by a chemical reaction between a fatty acid derived from a plant oil and an alcohol and that is a plant-derived ester mainly containing monoglycerides, or an electrical insulating oil made of a linear alkylbenzene, wherein the content of the first insulating oil is 1 to 15% by weight based on the total weight of the insulating oil composition. Aspect 1 is preferred from the viewpoint of realizing an electrical insulating oil that has high heat dissipation properties and is easy to handle under the Fire Service Act.

[0041] The insulating oil composition according to the second aspect of the present invention may have a flash point of 250°C or higher and a combustion point of 300°C or higher.

[0042] The insulating oil composition according to Aspect 3 of the present invention is the insulating oil composition according to Aspect 1 or 2, wherein the first insulating oil has a kinematic viscosity of 13 mm at 40°C. ２ Aspect 3 is preferred from the viewpoint of reducing the viscosity of the insulating oil composition and thereby realizing favorable heat dissipation characteristics.

[0043] The insulating oil composition according to Aspect 4 of the present invention may be configured in any one of Aspects 1 to 3, wherein the first insulating oil is the plant-derived ester, and the content of the plant-derived ester is 3 to 15 wt % based on the total amount of the insulating oil composition. Aspect 4 is preferable from the viewpoints of suitably reducing the viscosity and setting the flash point and fire point within suitable ranges.

[0044] The insulating oil composition according to Aspect 5 of the present invention may be configured such that, in any one of Aspects 1 to 3, the first insulating oil is the linear alkylbenzene, and the content of the linear alkylbenzene is 1 to 3% by weight based on the total amount of the insulating oil composition. Aspect 5 is preferred from the viewpoints of suitably reducing the viscosity and keeping the flash point and fire point within suitable ranges.

[0045] The insulating oil composition according to a sixth aspect of the present invention is the insulating oil composition according to the fifth aspect, wherein the linear alkylbenzene has a kinematic viscosity of 5 mm at 40°C.２ The use of a low-viscosity linear alkylbenzene as in embodiment 6 is preferred from the viewpoint of more suitably reducing the kinematic viscosity.

[0046] An oil-filled electrical device according to Aspect 7 of the present invention may be configured using the insulating oil composition according to any one of Aspects 1 to 6.

[0047] [Embodiment] An embodiment of the present invention will be described below.

[0048] Preparation of Insulating Oil Composition Example 1 Rapeseed oil (Sunohm ECO, Kanden Engineering Co., Ltd.) and palm fatty acid ester oil (Pastel NEO, Lion Specialty Chemicals) were mixed to prepare an insulating oil composition.

[0049] Example 2 An insulating oil composition was prepared in the same manner as in Example 1, except that soybean oil (Cargill, FR3) was used instead of rapeseed oil.

[0050] Comparative Example 1 An insulating oil composition was prepared in the same manner as in Example 1, except that mineral oil (Kanden Engineering, Sunohm MU) was used instead of palm fatty acid ester oil.

[0051] Comparative Example 2 An insulating oil composition was prepared in the same manner as in Example 2, except that mineral oil (Kanden Engineering, Sunohm MU) was used instead of palm fatty acid ester oil.

[0052] [Measurement of kinematic viscosity] The kinematic viscosity of each insulating oil composition was measured in accordance with JIS C 2101. The temperature at which the kinematic viscosity was measured was 40°C. The content of the first insulating oil in the insulating oil composition used for measuring the kinematic viscosity was 0%, 5%, 10%, 20%, 50%, 80%, 90%, 95% or 100% relative to the total amount of the insulating oil composition.

[0053] The measurement results for Examples 1 and 2 are shown in Figure 1. The measurement results for Comparative Examples 1 and 2 are shown in Figure 2. The kinematic viscosity of each insulating oil composition is shown in Table 1 below.

[0054] 1, 2 and Table 1, the kinematic viscosity of the insulating oil composition of Example 1 or 2 containing 5% or more of the first insulating oil was lower than the kinematic viscosity of the natural ester. Furthermore, when palm fatty acid ester oil was used as the first insulating oil, the kinematic viscosity of the insulating oil composition was lower than when the same amount of mineral oil was used.

[0055] [Flash Point Test] The flash point was measured in accordance with JIS K 2265, Section 7 (Cleveland open cup flash point test method). The flash point measurement conditions were as follows:

[0056] Test equipment: Herzog OptiFlash COC Sample amount: Approximately 80 mL Starting temperature: Room temperature Heating rate: 5-6°C / min (predicted flash point -28°C or higher) After measuring the flash point, the combustion point was measured in accordance with JIS K 2265, Section 7 (Cleveland open cup flash point test method).

[0057] The content of the first insulating oil in the insulating oil compositions used for measuring the flash point and fire point was 0%, 1%, 2%, 5%, 7%, 10%, 20%, 50%, 80%, or 100% of the total amount of the insulating oil composition.

[0058] The results of measuring the flash points of Example 1, Example 2, Comparative Example 1, and Comparative Example 2 are shown in Figure 3. In Figure 3, the regression curve created based on the results of Example 1 is y = -33.66ln(x) + 337.94, and R ２ = 0.9785. The regression curve created based on the results of Example 2 was y = -31.67ln(x) + 323.02, and R ２ = 0.9902. The regression curve created based on the results of Comparative Example 1 was y = -38.17ln(x) + 337.83, and R ２ = 0.9529. The regression curve created based on the results of Comparative Example 2 was y = -35.3ln(x) + 316.36, and R ２ = 0.9789. When Example 1 and Comparative Example 1 are compared, when the contents of the first insulating oil are the same, the flash point of Example 1 is higher. When Example 2 and Comparative Example 2 are compared, when the contents of the first insulating oil are the same, the flash point of Example 2 tends to be higher.

[0059] The measurement results for Examples 1 and 2 are shown in Figure 4. The measurement results for Comparative Examples 1 and 2 are shown in Figure 5. The measurement results for the flash point and fire point are shown in Table 2 below.

[0060]

[0061] [Summary] From the regression equation shown in Figure 1, it is predicted that in Example 1, when the content of the first insulating oil is 1.5% or more based on the total amount of the insulating oil composition, the kinematic viscosity of the insulating oil composition can be reduced by 5% or more compared to the kinematic viscosity of the natural ester. It was also found that in Example 1, when the content of the first insulating oil is 5% or more based on the total amount of the insulating oil composition, the kinematic viscosity of the insulating oil composition can be reduced by 8% or more compared to the kinematic viscosity of the natural ester. Furthermore, from the regression equation shown in Figure 3, it is predicted that the insulating oil composition of Example 1 will have a flash point of 250°C or higher when the content of the first insulating oil is 13.5% or less based on the total amount of the insulating oil composition. Furthermore, when the content of the first insulating oil is 10% or less based on the total amount of the insulating oil composition, the flash point was 250°C or higher and the fire point was 300°C or higher. It was found that in Example 1, a suitable insulating oil composition can be obtained when the content of the palm fatty acid ester oil, the first insulating oil, satisfies these ranges.

[0062] The regression equation shown in FIG. 1 predicts that in Example 2, when the content of the first insulating oil is 2% or more based on the total amount of the insulating oil composition, the kinematic viscosity of the insulating oil composition can be reduced by 5% or more compared to the kinematic viscosity of the natural ester. It was also found that in Example 2, when the content of the first insulating oil is 5% or more based on the total amount of the insulating oil composition, the kinematic viscosity of the insulating oil composition can be reduced by 8% or more compared to the kinematic viscosity of the natural ester. Furthermore, the regression equation shown in FIG. 3 predicts that the insulating oil composition of Example 2 will have a flash point of 250°C or higher when the content of the first insulating oil is 6.5% or lower based on the total amount of the insulating oil composition. Furthermore, when the content of the first insulating oil is 5% or lower based on the total amount of the insulating oil composition, the insulating oil composition of Example 2 had a flash point of 250°C or higher and a fire point of 300°C or higher. It was also found in Example 2 that a suitable insulating oil composition can be obtained when the content of the palm fatty acid ester oil, the first insulating oil, satisfies these ranges.

Claims

1. An insulating oil composition comprising: a first insulating oil selected from the group consisting of a plant-derived biodegradable electrical insulating oil, which is a natural ester mainly containing triglycerides; and a plant-derived ester mainly containing monoglycerides, which is a biodegradable electrical insulating oil containing an ester bond formed by a chemical reaction between a fatty acid derived from a plant oil and an alcohol, or an electrical insulating oil made of linear alkylbenzene, wherein the content of the first insulating oil is 1 to 15% by weight based on the total weight of the insulating oil composition.

2. The insulating oil composition according to claim 1, which has a flash point of 250°C or higher and a fire point of 300°C or higher.

3. The first insulating oil has a kinematic viscosity of 13 mm at 40°C. ２ 2. The electrical oil composition according to claim 1, wherein the electrical oil composition has a viscosity of 1000 kJ / s or less.

4. The insulating oil composition according to claim 1, wherein the first insulating oil is the plant-derived ester, and the content of the plant-derived ester is 3% by weight to 15% by weight based on the total weight of the insulating oil composition.

5. The insulating oil composition according to claim 1, wherein the first insulating oil is the linear alkylbenzene, and the content of the linear alkylbenzene is 1 to 3% by weight based on the total amount of the insulating oil composition.

6. The linear alkylbenzene has a kinematic viscosity of 5 mm at 40°C. ２ 6. The electrical oil composition according to claim 5, wherein the electrical oil composition has a viscosity of less than 1000 MPa.

7. An oil-filled electrical device using the insulating oil composition according to any one of claims 1 to 6.

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