JPH0676635A - Oil-immersed electric appliance - Google Patents

Abstract

PURPOSE:To suppress the dissolution of copper in an insulating oil of an oil- immersed electric appliance by setting the amount of an aromatic component in the insulating oil to be a specified amount or more and adding 1,2,3- benzotriazole to the oil. CONSTITUTION:Regarding an oil-immersed electric appliance wherein a structural body made of copper or a copper alloy is immersed in an insulating oil, 0.5-30mg/l or less of 1,2,3-benzotriazole is added to the insulating oil. In the oil-immsersed electric appliance, 1,2,3-benzotriazole reacts with copper quickly and forms a coating which makes the copper surface inert, so that copper is suppressed from being dissolved in the insulating oil. In this way, dissolution of copper or the copper alloy in the oil is suppressed and an effect on appliance' s abnormality diagnosis based on the dissolution is removed and thus reliable maintenance of the electric appliance can be done.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an oil-filled electric device, and more particularly to a technique for suppressing dissolution of copper in insulating oil.

[0002]

2. Description of the Related Art Generally, an abnormality of an oil-filled electric device is accompanied by arc discharge, partial discharge, overheating and the like. At that time, the insulating material and the insulating oil are thermally decomposed to generate various gases and are dissolved in the insulating oil. Utilizing this phenomenon, abnormality diagnosis of oil-filled electrical equipment is generally performed by analysis of flammable gas dissolved in oil. By the way, there is a phenomenon that copper is dissolved in insulating oil, which is difficult to think from a sensory point of view. It became clear that the molten copper acts as a catalyst to promote the deterioration of insulating oil and affects the generation of flammable gas, as described later.

That is, it was said that the dissolution of copper occurs in the presence of oxygen, but it was found that the sulfur compound in the insulating oil is mainly involved even without oxygen. Commercially available mineral oil-based insulating oil contains about 0.01 to 0.3% of sulfur compounds. Therefore, copper will be dissolved even in an electrical device that is protected from oxidative deterioration. In addition, it was confirmed that it was dissolved. So far, there is no knowledge about the dissolution of copper, and no cases were examined for its countermeasures.

[0004]

As described above, in conventional oil-filled electrical equipment, copper is dissolved in insulating oil even if measures against oxidative deterioration are taken, and the dissolved copper serves as a catalyst. It became clear that the insulating oil deteriorates and combustible gas is generated even if the electrical equipment is not abnormal, which adversely affects the abnormality diagnosis. The present invention has been made to solve the above problems, and an object of the present invention is to provide an oil-filled electrical device that suppresses the dissolution of copper in insulating oil and does not hinder abnormality diagnosis.

[0005]

In an oil-filled electric device according to the present invention, the insulating oil has an aromatic content of 10% or more, and the insulating oil contains 0,2,3-benzotriazole. 0.5 mg / l or more and 30 mg / l or less are added.

[0006]

Function: 1,2,3-Benzotriazole promptly reacts with copper to form a film that inactivates the copper surface, so that the dissolution of copper in insulating oil is suppressed.

[0007]

【Example】

Example 1. The experimental results based on the present invention will be described below. Two types of commercially available insulating oil were used in the experiment, but these were all JIS C 2320, I
It satisfies the standards such as EC 296 Class I. The general characteristics of the commercial insulating oils 1 and 2 are shown in FIG. A well-polished 30 mm × 50 mm × 3 mm copper plate was immersed in 70 ml of insulating oil and heated at 120 ° C. for 40 hours to measure the amount of dissolved copper. The insulating oil was degassed in vacuum before use, and normally nitrogen was used on the oil surface. Only when investigating the effect of oxygen, a fixed amount of oxygen was filled on the oil surface. As the additive, 1,2,3-benzotriazole (hereinafter, referred to as B
(Hereinafter referred to as TA) and, as a comparative example, 2,6-ditertiarybutylparacresol (hereinafter referred to as DBPC), which has been conventionally used as an antioxidant, was used.

For commercial insulating oil 1, BTA is 0 to 30 m
FIG. 1 shows the relationship between the amount of dissolved copper in oil and the BTA concentration when g / l was added. When 1 mg / l or more of BTA was added, dissolved copper was not detected. Although it was detected at 0.5 mg / l, it was considerably smaller than that in the case of no addition, and it is considered that even at this concentration, there is an inhibitory effect. FIG. 2 shows the relationship between the amount of dissolved copper and the added amount of the commercially available insulating oil 2 when 0 to 30 mg / l of BTA was added. Commercially available insulating oil 2 is an insulating oil in which copper is fairly easily dissolved, and without addition, about 6 times as much molten copper as in commercially available insulating oil 1 was detected. However, when BTA was added at 1 mg / l or more, no dissolved copper was detected. As described above, BTA has an action of suppressing copper dissolution regardless of the type of insulating oil.

Further, as comparative examples, 0.1% and 0.3%
FIG. 3 shows the results of investigating the relationship between the amount of dissolved copper and the amount added by adding DBPC of No. 1 to commercial insulating oils 1 and 2, respectively. Although the commercial insulating oil 2 shows some reduction, the commercial insulating oil 1 has no effect, so it cannot be said to be effective in suppressing copper dissolution. The reason why the commercially available insulating oil 2 shows some decrease is that DBPC has an action of preventing oxidative deterioration,
It is considered that the secondary copper dissolution due to the organic acid or the like generated by the oxidative deterioration is only suppressed.

Next, in order to investigate the effect of oxygen, the results of the amount of dissolved copper measured by enclosing 7.4 ml of oxygen in the space above the oil surface of the insulating oil containing no BTA and adding 15 mg / l are shown in FIG. Shown in. As shown in the figure, the BTA-added oil shows the effect of suppressing copper dissolution even in the state of oxygen on the oil surface. On the other hand, in the additive-free oil, the amount of dissolved copper is larger when oxygen is present on the oil surface.
Although there is an idea that oxygen forms a protective film on the copper surface and suppresses dissolution of copper, the experimental results of the above additive-free oil show a rather opposite tendency.

Next, the factors affecting the dissolution of copper were investigated using 12 kinds of commercially available mineral oil type insulating oils and synthetic type insulating oils having a sulfur content of 1 ppm or less. Similar to the difference between the above-mentioned commercially available insulating oils 1 and 2, there is a considerable difference in the amount of molten copper depending on the brand. When the amount of dissolved copper is sorted by focusing on the amount of sulfur, the relationship as shown in FIG. 5 is obtained. The amount of dissolved copper tended to increase as the amount of sulfur increased, and no copper dissolved in the synthetic insulating oil. Here, the above-mentioned oxygen coexistence experiment is considered as follows. Considering the competitive reaction in the coexistence state of sulfur, BTA and oxygen on the copper surface from the above experimental results, it is BTA that has the fastest reaction, the sulfur compound next, and the slowest oxygen. Therefore, once BTA reacts with copper, sulfur and the like cannot react, and copper dissolution is suppressed.

When the relationship between the amount of dissolved copper and the combustible gas was examined for the above-mentioned 12 types of commercial insulating oils, the results shown in FIG. 6 were obtained. As shown in the figure, when the amount of dissolved copper in oil increases, the generation of combustible gas increases. In addition, no combustible gas was generated in synthetic oil-based insulating oil. Such a phenomenon of mineral oil-based insulating oil is not preferable for oil-filled electrical equipment in which abnormality or life is determined from the value of the amount of combustible gas in insulating oil. Therefore, it is considered necessary to add BTA to suppress copper dissolution for maintenance of oil-filled electrical equipment.

As mentioned above, BTA is 0.5 to 30 mg.
The effect is seen in a wide range such as / l. However, in an oil-filled electric device, there is an adsorption action to an insulator, and from this point, it is preferable that the addition amount is large. However, B
TA has a property that it is extremely difficult to dissolve in mineral oil type insulating oil. FIG. 7 shows the saturated solubility of BTA in insulating oil, and the more aromatic component the insulating oil contains, the easier it is to dissolve. Therefore, the saturated solubility at room temperature is 500 mg / l or less, which is extremely lower than the saturated solubility in DBPC of 10,000 mg / l or more.

This low solubility poses a problem especially at low temperatures. That is, the saturation solubility is lowered in a low temperature range, and once BTA is precipitated, the BTA concentration in the oil is lowered, its concentration distribution becomes non-uniform, and it takes a long time to redissolve. On the other hand, the pour point of electrical insulating oil specified by JIS C 2320 is -27.5 ° C. The pour point is often set to 10 ° C. above the ambient temperature. Therefore, the minimum operating temperature of electrical equipment is considered to be -17.5 ° C, and even at such temperatures, BT will not be oversaturated.
A must be added.

If the aromatic component of the insulating oil is set to 10% or more in consideration of the above temperature conditions and the solubility characteristic of FIG. 7, the concentration of BTA does not precipitate at the operating temperature of the oil-filled electrical equipment and the concentration is 30 mg / It is possible to realize l.

Example 2. Use brass instead of copper, B
FIG. 8 shows the result of measuring the dissolved copper amount of the insulating oil to which TA was added at 0 mg / l and 15 mg / l. Although less than copper, it was found that copper was dissolved in the additive-free oil. B
TA also has a dissolution inhibiting effect on brass.

Embodiment 3. In each of the above examples, the case where BTA is directly added to the insulating oil used in the oil-filled electrical equipment has been described, but once BTA is dissolved in the oil having a high aromatic component to make a high-concentration oil, and thereafter, Alternatively, it may be diluted to a predetermined concentration. That is, the synthetic insulating oil such as alkylbenzene and polycyclic aromatic oil has an aromatic content of 30% or more. When used, the saturated solubility near the pour point becomes a problem, but at the time of production, the saturated solubility near room temperature is preferably high. As shown in FIG. 7, both the alkylbenzene and the polycyclic aromatic oil have higher saturated solubilities of BTA at around room temperature than the mineral oil-based insulating oil by about one digit. Therefore, in such a high aromatic oil, a large amount of BTA is obtained at a low temperature as compared with the mineral oil type insulating oil.
Can be dissolved. By finally diluting the BTA high-concentration oil obtained above with the insulating oil used in electric equipment, the work of dissolving BTA becomes simple.

[0018]

As described above, according to the present invention, the insulating oil has an aromatic content of 10% or more, and 1,2,3-benzotriazole is contained in the insulating oil at 0.5 mg / l or more and 30 mg or more. Since the amount added is 1 / l or less, the dissolution of copper or copper alloy in the oil is suppressed, and the influence on the device abnormality diagnosis based on this dissolution is removed, and reliable maintenance and management of electric devices becomes possible.

[Brief description of drawings]

FIG. 1 is a graph showing the relationship between the amount of dissolved copper and the amount of BTA added when a commercially available insulating oil 1 is used, which is an experimental result based on Example 1 of the present invention.

FIG. 2 is a graph showing the relationship between the amount of dissolved copper and the amount of BTA added when a commercially available insulating oil 2 is used, which is an experimental result based on Example 1 of the present invention.

FIG. 3 is an experimental result as a comparative example, showing that commercially available insulating oils 1 and 2 are used.
It is a figure which shows the relationship between the amount of dissolved coppers, and the amount of DBPC additions when using.

FIG. 4 is a diagram showing the relationship between the amount of dissolved copper and the amount of BTA added in the coexistence of oxygen, as an experimental result based on the present invention.

FIG. 5 is a diagram showing the relationship between the amount of sulfur and the amount of dissolved copper, which is an experimental result as a reference example.

FIG. 6 is a diagram showing the relationship between the amount of dissolved copper and the amount of combustible gas, which is an experimental result as a reference example.

FIG. 7 is a diagram showing temperature characteristics of BTA saturated solubility with the amount of an aromatic component as a parameter.

FIG. 8 is a graph showing the relationship between the amount of dissolved copper and the amount of BTA added when using commercially available insulating oils 1 and 2 as an experimental result based on Example 2 of the present invention.

FIG. 9 is a table showing characteristics of commercially available insulating oils 1 and 2 as sample oils.

Claims (1)

[Claims] 1. An oil-filled electrical device in which a component made of copper or a copper alloy is immersed in insulating oil, wherein the insulating oil has an aromatic component content of 10% or more, and An oil-filled electric device comprising 2,3-benzotriazole added in an amount of 0.5 mg / l or more and 30 mg / l or less.