JPH117831A - Oil-filled electric equipment - Google Patents

Abstract

PROBLEM TO BE SOLVED: To enable size reduction, lower the fluidity point, heighten the injecting point, improve safety, and reduce adverse influence on a member used for a transformer by filling at least one kind of dialkyl diphenyl alkane. SOLUTION: A material composed of at least one kind of dialkyl diphenyl alkane expressed by the formula (where, R1 represents a saturated aliphatic hydrocarbon residue having the carbon number 1 or 2, and R2 and R3 represent a straight chain or branched saturated aliphatic hydrocarbon radical having the same or different carbon number 3 or 4), is used as electric insulation oil. A saturated aliphatic series having the carbon number 3 is exemplified as a concrete example of R2 and R3 in the formula, and an (n)-propyl group, an (sec)-propyl group or the like are exemplified as a hydrocarbon radical, and an (n)-butyl group, an (sec)-butyl group, an (iso)-butyl group, a tert-butyl group or the like are exemplified as a saturated aliphatic hydrocarbon radical having the carbon number 4. There are dipropyl diphenyl methane, propyl butyl diphenyl methane or the like as examples of the insulating oil.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an oil-filled electrical device such as a cable, a capacitor, an electric circuit breaker, and a transformer filled with an electrical insulating oil. And has excellent thermal stability and does not affect the components used in the transformer.
TECHNICAL FIELD The present invention relates to an oil-filled electric device in which a dialkyldiphenylalkane having a specific structure is injected or filled, particularly to an oil-filled transformer.

[0002]

2. Description of the Related Art In recent years, oil-containing electric devices such as transformers, circuit breakers, and condensers that use electric insulating oil have been increased in size in accordance with an increase in power consumption. As a result, a high degree of safety and long-term stability of equipment are required, and requirements for electric insulating oil to be injected into equipment are becoming more severe.
For example, large transformers are typically installed outdoors, and their operating temperatures can range from high to low temperatures. Transformers also have losses such as iron loss and copper loss, all of which are converted to heat, and this heat raises the temperature of the transformer oil, which can be up to 90 ° C depending on fluctuations in transformer load and ambient temperature. ° C. Accordingly, the transformer oil filled in the transformer is exposed to a wide range of temperature changes. Since the transformer oil causes a volume change due to this temperature change, the inside and outside air repeatedly enters and exits in the open type transformer. Since this air comes into contact with the transformer oil, both the air and the heat generated in the transformer promotes the deterioration of the transformer oil, resulting in a shortened life of the transformer.

[0003] In order to prevent the transformer oil from deteriorating, some contrivances have been made such as installing a conservator so that only a part of the oil comes into contact with air, or enclosing nitrogen in the transformer to make it a sealed type. However, it is not always enough to prevent oil deterioration, and it is necessary to periodically replace transformer oil that deteriorates.

Conventionally, transformer oils include refined mineral oil,
Synthetic oils such as silicone oil, polybutene, and alkylbenzene are used. However, mineral oils such as paraffinic and naphthenic oils and alkylbenzenes have poor thermal stability, and paraffin oils and naphthenic oils generally have a lower ignition point than aromatic hydrocarbons. Does not have satisfactory properties. In addition, polybutene has a high viscosity, and silicone oil is very expensive. Therefore, it is considered that it is difficult to use it as a transformer oil in terms of cost.

[0005] Further, transformer oil changes its volume under the influence of heat generated inside the transformer, and also causes thermal deterioration. Therefore, transformer oil not only requires high electrical characteristics, but also has a small volume change with temperature change,
In addition, stability and safety that do not cause thermal deterioration are required.
For example, in a typical transformer, the amount of transformer oil may account for about 80% by volume (about 30% by weight) of the total transformer volume. If the coefficient of thermal expansion of transformer oil, which occupies most of the volume of the transformer, is large, the amount of change in volume due to oil temperature change will occupy a very large amount with respect to the total volume of the transformer. . Therefore, in the case of an open type transformer, the entire equipment becomes large due to its large volume, and in the case of a closed type transformer, the internal pressure increases, which requires the mechanical strength of the equipment and the container. Become. In any case, when the coefficient of thermal expansion of the transformer oil is large, the size of the transformer increases and the manufacturing cost increases. From this, it is required that the coefficient of thermal expansion of the transformer oil is small.

[0006] Further, since the transformer is generally installed outdoors even in a cold region, the transformer oil is required to have a low pour point and viscosity and to have good fluidity. If the fluidity of the transformer oil is insufficient, the heat generated in the transformer will accumulate inside the transformer, causing a local temperature rise.

[0007] Further, the decomposition gas of the oil accompanying the generation of corona in the transformer oil causes the generation of corona at an accelerated rate and accelerates the deterioration of the oil. Transformer oil generally has the effect of absorbing this gas to suppress the generation of corona at an accelerated rate.However, if the fluidity of the oil is poor, the absorption rate of the gas will be extremely reduced and the oil Promotes the deterioration of Therefore, it is desired that the transformer oil has good fluidity. Therefore,
Transformer oil is desired to have high hydrogen gas absorption,
Since this characteristic is caused by an olefin, an aromatic ring and the like in the oil component, an oil having high aromaticity is generally preferred. However, highly aromatic oils have large dissolving power and penetrating power and may adversely affect members used in transformers.

In addition, since the power transformer is used in apartments, hospitals, schools, factories, etc., it is necessary to consider the safety of the transformer against fire and the like. That is, the temperature of the transformer oil can reach 90 ° C,
In consideration of safety, the flash point of transformer oil is required to be 130 ° C. or higher.

[0009]

SUMMARY OF THE INVENTION An object of the present invention is to provide an oil-filled transformer filled with transformer oil having a small coefficient of thermal expansion in view of the above-mentioned circumstances. Another object of the present invention is to provide an oil-filled transformer filled with transformer oil having good fluidity. It is another object of the present invention to provide an oil-filled transformer filled with transformer oil having high hydrogen gas absorbability and having little adverse effect on members used in the transformer.
Another object of the present invention is to provide an oil-filled transformer filled with transformer oil having a high flash point and excellent safety against fires and the like.

[0010]

Means for Solving the Problems The present inventors have conducted intensive studies in view of the above-mentioned object, and as a result, have found that a transformer oil satisfying the required performance can be obtained by using a specific diphenylalkane. The invention has been completed. That is, the first aspect of the present invention relates to an oil-filled electrical device filled with at least one kind of dialkyldiphenylalkane represented by the following formula [I].

[0011]

Embedded image

Wherein R ₁ is a saturated aliphatic hydrocarbon residue having 1 or 2 carbon atoms, and R ₂ and R ₃ are linear or branched saturated aliphatic hydrocarbon groups having 3 or 4 carbon atoms, which are the same or different. Is shown. A second aspect of the present invention relates to the oil-filled electrical device according to the first aspect of the present invention, wherein the electrical device is a transformer.

[0013]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, the present invention will be further described.
The insulating oil used in the present invention is represented by the above formula [I], and as specific examples of R ₂ and R _{3 in} the formula, as a saturated aliphatic hydrocarbon group having 3 carbon atoms, n-propyl group, sec- Examples include a propyl group and the like, and examples of the saturated aliphatic hydrocarbon group having 4 carbon atoms include an n-butyl group, a sec-butyl group, an iso-butyl group and a tert-butyl group. Here, R ₂ and R ₃ can be bonded to the same benzene ring or can be bonded to different benzene rings, respectively, but the latter bonded to a different benzene ring is preferable. Dialkyldiphenylalkanes having 2 or less carbon atoms in R ₂ and R ₃ are not preferable as transformer oils because the aromaticity is too high and the members used for the transformer are dissolved or swelled. On the other hand, dialkyldiphenylalkanes having more than 4 carbon atoms in R ₂ and R ₃ tend to have low oxidation stability, and therefore are disadvantageous for use in electrical insulating oils, especially transformer oils.

Specific examples of the dialkyldiphenylalkane represented by the above formula [I], which is the electric insulating oil used in the present invention, include dipropyldiphenylmethane, for example, dipropyldiphenylmethane.
(Propylphenyl) methane; propylbutyldiphenylmethane such as (propylphenyl) (butylphenyl) methane; dibutyldiphenylmethane such as di (butylphenyl) methane; dipropyldiphenylethane (1,
1), for example, di (propylphenyl) ethane (1,1); dipropyldiphenylethane (1,2), for example di (propylphenyl) ethane (1,2); propylbutyldiphenylethane
(1,1), for example (propylphenyl) (butylphenyl)
Ethane (1,1); propylbutyldiphenylethane (1,2),
For example, (propylphenyl) (butylphenyl) ethane
(1,2); dibutyldiphenylethane (1,1), e.g.
(Butylphenyl) ethane (1,1); dibutyldiphenylethane (1,2) such as di (butylphenyl) ethane (1,2); These dialkyldiphenylalkanes can be prepared by a conventionally known method, for example, diphenylmethane, diphenylethane (1,1) or diphenylethane (1,2).
And the like.

The insulating oil used in the present invention may be mixed with a known electric insulating oil, for example, phenylxylylethane (PXE). Although the insulating oil of the present invention has excellent thermal stability, in order to further improve the thermal stability, 2,6-dibutyl-methylphenol (DBPC), 2,6-dibutylphenol (DBP)
And other known antioxidants.
It is also possible to add a flowing antistatic agent such as 1,2,3-benzotriazole (BTA) and a pour point depressant such as polymethacrylate (PMA) and olefin copolymer (OCP).

The electrical insulating oil used in the present invention is a cable,
It is suitable for filling capacitors, electric circuit breakers, transformers and the like. In particular, it is suitable for filling or filling an oil-filled transformer. The oil-immersed transformer of the present invention is a power transformer for boosting / dropping a voltage generated at a power plant at a power plant or a substation, a distribution transformer for lowering a primary voltage to a secondary voltage, a vehicle transformer, The present invention is not limited to a special transformer for an electric furnace or the like, and can be used as any type of transformer. Usually, it is suitable as a medium-sized and large-sized oil-filled transformer, for example, a power transformer. All oil-filled transformers use directional silicon steel strip, cold-rolled silicon steel strip, amorphous magnetic ribbon, etc. as iron cores, and are self-cooled with oil, air-cooled with oil, water-cooled with oil, self-cooled with oil feed, and oil sent. Various cooling methods for the filling oil or the injection oil, such as air cooling and oil supply water cooling, can be adopted. Transformer materials that come into contact with transformer oil include varnishes, rubbers, adhesives, and the like. The electrical insulating oil used in the present invention has a particular effect on the characteristics of transformers even if it is in long-term contact with these materials. I will not give. The injection and filling of the insulating oil into the transformer can be appropriately performed by a known method.

[0017]

The present invention will be further described with reference to the following examples. <Example 1> insulating oil used was a mixed oil having the following composition, diisopropyl diphenyl ethane: 91 wt% diarylalkane: residual aromatic Zokudo was 59% C _A. The aromaticity (%
C _A ) was measured by ¹³ C-NMR method. The components of the above-mentioned mixed oil are classified according to the substitution form as follows: (1) Diaryl containing di (isopropylphenyl) ethane, wherein a saturated aliphatic hydrocarbon group is bonded to two benzene rings one by one each. Alkane: 69% by weight (2) Contains (diisopropylphenyl) phenylethane, and a saturated aliphatic hydrocarbon group is contained only in one benzene ring.
Individually bonded aryl phenylethane: 31% by weight The electrical properties are shown in Table 1, and the physical properties are shown in Table 2.

Example 2 The insulating oil used was a mixed oil having the following composition: di-sec-butyldiphenylmethane: 53% by weight Di-sec-butyldiphenylethane (1,1): 27% by weight di -sec- butyl diphenylethane (1,2): 20 wt% aromatic Zokudo was 56% C _a. The components of the mixed oil are classified according to the substitution form as follows: (1) di (sec-butylphenyl) methane, di (sec-butylphenyl) ethane (1,1) and di (sec-butylphenyl) )
A diarylalkane containing ethane (1,2) and having a saturated aliphatic hydrocarbon group bonded to two benzene rings, one for each: 6
0% by weight (2) di (sec-butylphenyl) phenylmethane, di (sec
-Butylphenyl) phenylethane (1,1) and di (sec-
Butyl) phenylethane (1,2), and an aryl. Wherein two saturated aliphatic hydrocarbon groups are bonded to only one benzene ring.
Phenylalkane: 40% by weight The electrical properties are shown in Table 1, and the physical properties are shown in Table 2.

<Comparative Examples 1 to 5> The insulating oils used are as follows. Table 1 shows the electrical characteristics and Table 2 shows the physical properties.

[0020]

[Table 1]

[0021]

[Table 2]

The insulating oils of Examples 1 and 2 have a smaller coefficient of thermal expansion than most of the conventional products shown in Comparative Examples.
Small volume change due to temperature change. From this, when the insulating oil of the embodiment is used as the transformer oil, the space of the open type transformer can be reduced because the oil expansion is small, and the pressure change in the closed type transformer can be reduced. , The pressure resistance of the container can be reduced. In any case, by using the insulating oil of the embodiment, it is possible to reduce the size of the transformer as compared with the case where the conventional oil is used.
Further, the insulating oils of Examples 1 and 2 can be used in cold regions because their pour points are −40 ° C. or lower, and have a higher flash point. It is clear that it is suitable for transformer oil.

Transformer oil plays a role of radiating heat generated in the transformer to the outside. In order to enhance the heat radiation effect, it is desirable that the oil has a low viscosity. Therefore, the stability to heat was measured for an oil having a low kinematic viscosity and a pour point of −40 ° C. or less. As a measuring method, an oxidation stability test (ASTM-D-1934) for examining the degree of thermal deterioration was used, the total acid value of the deteriorated oil was measured, and a multiple of the total acid value of the new oil before the test in Example 1 was determined. Was. Table 3 shows the results of the evaluation based on the following criteria. Criteria: Total acid value of the new oil of Example 1 ：: less than 30 times ：: 30 times to less than 100 times △: 100 times to less than 300 times ×: 300 times or more

[0024]

[Table 3]

The oils of Comparative Examples 3 and 4 showed values of 11 to 51 times or more as compared with the oils of the Examples, and the oil of Comparative Example 5 also showed a deterioration of 6 times or more without copper wire. From the above, it can be seen that the insulating oils of the examples have better heat stability than the conventional products shown in the comparative examples.

The oil of Comparative Example 5 has slightly better stability but higher aromaticity. Oils with a high degree of aromaticity have a large dissolving power and a high penetrating power, and thus may affect members that come into contact with the oil. Therefore, a dipping test of the members was performed using the oils of Examples 1 and 2 and the oil of Comparative Example 5 having a high aromaticity, and the weight change rate was obtained. The test conditions are as follows. Immersion member: Fluorine rubber, dimensions 20 mm × 50 mm × 2 mm Immersion temperature: 80 ° C. Immersion time: 20 hours The results of evaluation based on the following criteria are shown in Table 4. ：: Weight change rate less than 0.3% △: 〃 0.3% to less than 1.0% ×: １ 1.0% or more

[0027]

[Table 4]

As shown in the table, there is almost no change in the members immersed in the oil of the example, and it is understood that the transformer oil used in the present invention does not affect the members used.

[0029]

As described above, the transformer oil used in the present invention has a small coefficient of thermal expansion, so that the transformer can be downsized as compared with the conventional transformer oil, and the pour point is low and the flash point is high. Therefore, it is the most suitable oil for transformer oil because of its high safety and excellent long-term stability against heat. Further, it hardly affects members used for the transformer.

Claims (2)

[Claims] 1. An oil-filled electric device filled with at least one dialkyldiphenylalkane represented by the following formula [I]. Embedded image [However, R ₁ represents a saturated aliphatic hydrocarbon residue having 1 or 2 carbon atoms, and R ₂ and R ₃ represent a straight or branched saturated aliphatic hydrocarbon group having 3 or 4 carbon atoms which are the same or different. ] 2. The oil-filled electrical device according to claim 1, wherein the electrical device is a transformer.