Method for inhibiting oil sulfur corrosion of oil-immersed power equipment

Abstract

The invention belongs to the field of corrosion and protection of power grid materials, and particularly relates to a method for inhibiting oil sulfur corrosion of oil-immersed power equipment. The antioxidant T531 and the metal deactivator Irgamet 39 are added into the transformer insulating oil, when the concentration ratio of the T531 to the Irgamet 39 is smaller than 0.5, the oil sulfur corrosion of a copper winding is well inhibited, the influence on the performance of the insulating oil is small, the copper element content in the insulating oil does not exceed an attention value of 0.5 mg / kg, and the dielectric loss does not exceed a standard value of 0.02. The direct current resistivity is higher and is larger than 160 * 10 < 9 > omega.m, and the acid value of the insulating oil is lower and is smaller than 0.016 mgKOH / g; after the antioxidant and the metal deactivator are mixed according to the proportion, the oil sulfur corrosion resistance of the copper winding is greatly improved, the aging of insulating oil is inhibited, and the antioxidant has very high application potential in an oil-immersed transformer.

Description

Technical Field

[0001] The invention belongs to the field of corrosion and protection of power grid materials, in particular to a method for inhibiting oil-sulfur corrosion of oil-immersed power equipment. Background Art

[0002] As the most basic and critical equipment in the power grid, the reliability of oil-immersed transformers directly affects the safe and stable operation of the power system. In the internal insulation of oil-immersed transformers, the oil-paper insulation system plays a very important role.

[0003] This phenomenon is mainly manifested in two aspects: First, the corrosive sulfur in the insulating oil reacts with the copper winding to generate cuprous sulfide (Cu2S) with relatively strong conductivity, which is deposited on the insulating paper and transferred between the layers of the insulating paper, reducing its resistivity and increasing dielectric loss; on the other hand, the intermediate product (DBDS-Cu) and part of the Cu2S generated by the corrosion of the copper winding by sulfur enter the insulating oil in the form of ions and particles, respectively, resulting in an increase in the copper content in the oil. Copper and its ions themselves will reduce the volume resistivity of the insulating oil and significantly increase the dielectric loss. In addition, they can also act as catalysts to accelerate the aging of the insulating oil; both of these phenomena are the main causes of such accidents. Domestic and foreign scholars have conducted in-depth research on the generation mechanism, influencing factors and harm of corrosive sulfides to transformer oil-paper insulation, and proposed several solutions, such as replacing transformer oil, strictly accepting new oil, chemically removing corrosive sulfur and adding metal passivators to insulating oil. Among them, the cost of replacing transformer insulating oil is high, and chemical removal is selective to the type of oil. Therefore, adding metal passivators is widely used.

[0004] According to experience, the normal value of copper content in operating oil is 0.02mg / kg, and the attention value is 0.5mg / kg (exceeding this value, the dielectric loss of insulating oil becomes unstable, and the dielectric loss of insulating oil should be less than 0.02), and it is found that the main transformer in the 220kV substation equipment is prone to abnormal copper content. The corrosive sulfur content in the insulating oil was tested and it was found that the corrosive sulfur in the transformer insulating oil with excessive copper content was also high, while no corrosive sulfur was detected in the transformer oil with normal copper content. In recent years, with the rapid development of power grids, especially the development of ultra-high voltage transmission and transformation technology, the capacity, load and voltage level of power transformers have increased day by day, and the probability of sulfur corrosion failure threatening the oil-paper insulation system has increased exponentially, so the requirements for sulfur corrosion protection are also higher. Summary of the invention

[0005] The purpose of the present invention is to overcome the shortcomings of the prior art and provide a method for inhibiting oil-sulfur corrosion of oil-immersed power equipment, which has a good inhibitory effect on oil-sulfur corrosion of copper windings and aging of insulating oil.

[0006] The present invention uses antioxidant T531 (N-phenyl-α-naphthylamine) and Irgamet 39 (a derivative of methylbenzotriazole) in a compound according to a certain ratio, which can inhibit the oil-sulfur corrosion and insulating oil aging of power equipment. In experiments, it is found that when the concentration ratio of T531 and Irgamet 39 is less than 0.5, the effect of inhibiting oil-sulfur corrosion and insulating oil aging is better.

[0007] Furthermore, the concentration ratio of T531 to Irgamet 39 is 0.1 to 0.5.

[0008] Furthermore, the total amount of antioxidant T531 and metal passivator Irgamet 39 added to each kilogram of transformer insulating oil is 80 to 120 mg.

[0009] The advantages and positive effects of the present invention are:

[0010] The present invention uses antioxidant T531 (N-phenyl-α-naphthylamine) and Irgamet 39 (a derivative of methylbenzotriazole) in a certain ratio, and suppresses the oil-sulfur corrosion of power equipment and the degree of insulating oil aging by adjusting the concentration ratio of the commonly used antioxidant T531 (N-phenyl-1-naphthylamine) and Irgamet 39 (a derivative of methylbenzotriazole). And through corrosion tests and performance tests, it is found that when the concentration ratio of T531 and Irgamet 39 is less than 0.5, it has a good inhibitory effect on the oil-sulfur corrosion of copper windings, and has little effect on the performance of insulating oil, wherein the copper content in the insulating oil does not exceed the attention value of 0.5 mg / kg, and the dielectric loss does not exceed the standard value of 0.02. The DC resistivity is relatively high, both greater than 160×10 9 Ω·m, the acid value of the insulating oil is low, all less than 0.016mgKOH / g; after the antioxidant and metal passivator are mixed using this ratio, the oil-sulfur corrosion resistance of the copper winding is greatly improved, and the aging of the insulating oil is inhibited, which has a high application potential in oil-immersed transformers. BRIEF DESCRIPTION OF THE DRAWINGS

[0011] Figure 1 The copper content in insulating oil at different ratios of T531 and Irgamet 39;

[0012] Figure 2 The copper content on the insulating paper at different ratios of T531 and Irgamet 39;

[0013] Figure 3 The dielectric loss of insulating oil under different ratios of T531 and Irgamet 39;

[0014] Figure 4The volume resistivity of insulating oil under different ratios of T531 and Irgamet 39;

[0015] Figure 5 The acid value of insulating oil under different ratios of T531 and Irgamet 39. DETAILED DESCRIPTION

[0016] The present invention is further described in detail below through specific examples. The following examples are only illustrative and not restrictive, and the protection scope of the present invention cannot be limited thereto.

[0017] The corrosion test was conducted to study the inhibitory effect of different concentration ratios of antioxidant T531 and metal passivator Irgamet 39 on oil-sulfur corrosion of copper windings and the influence of insulating oil. The copper windings used in this experiment were all original windings without treatment. The concentration ratios of antioxidant T531 and metal passivator Irgamet 39 and the test conditions are shown in Table 1.

[0018] Table 1 Concentration ratios of different antioxidants T531 and metal passivator Irgamet 39 and corrosion test conditions

[0019]

[0020] The test instruments and methods are shown in Table 2.

[0021] Table 2 Test instruments and methods

[0022]

[0023] The antioxidant T531 and the metal passivator Irgamet 39 were tested at different concentration ratios (1:10, 3:10, 5:10, 7:10, 9:10, 10:10). According to the IEC 62535 standard, the oil-sulfur corrosion test was carried out at 150°C for 3 days with a concentration of 500 mg / kg of DBDS. After the test, the copper winding was taken out. First, the copper content in the insulating oil after corrosion was tested. Figure 1 The test results show that when the concentration ratio of T531 to Irgamet 39 is less than 0.5, the copper content in the insulating oil is low, all below 0.5 mg / kg. When the ratio is 1:10, the copper content in the insulating oil is the lowest, at 0.133 mg / kg. When the ratio is 10:10, the copper content in the oil is the highest, at 0.765 mg / kg.

[0024] After the corrosion test, the copper content on the insulating paper was tested. The test results are as follows: Figure 2As shown. Its rule is the same as the copper content in insulating oil. When the concentration ratio of T531 to Irgamet 39 is less than 0.5, the copper content on the insulating paper is low. When the ratio is greater than 0.5, the copper content on the insulating paper increases rapidly due to the decrease in the passivation agent content and the increased corrosion of the copper winding. When the ratio of T531 to Irgamet 39 is 1:10, the copper content on the insulating paper is the lowest, at 1.213 mg / kg. When the ratio is 10:10, the copper content on the insulating paper is the highest, at 5.676 mg / kg.

[0025] The results of dielectric loss and volume resistivity are important indicators of the performance of insulating oil, and can also reflect the degree of corrosion of the winding. Figure 3 The dielectric loss test results of insulating oil after corrosion test under different concentration ratios of T531 and Irgamet 39 are shown in the figure. It can be seen from the test results that with the increase of the concentration ratio of the two, the dielectric loss of insulating oil after corrosion test first increases slowly and then rises rapidly. When the concentration ratio of T531 and Irgamet 39 is less than 0.5, the dielectric loss of insulating oil is low, both lower than 0.02, indicating that T531 and Irgamet 39 within this range can effectively inhibit the oil-sulfur corrosion of copper windings without causing increased dielectric loss. When the ratio of T531 and Irgamet 39 is 1:10, the dielectric loss of insulating oil is the lowest, which is 0.0148. When the ratio of T531 and Irgamet 39 is 10:10, the dielectric loss of insulating oil is the highest, which is 0.0611.

[0026] Figure 4 The DC resistivity test results of the insulating oil after the corrosion test at different T531 and Irgamet 39 concentration ratios are shown in the figure. It can be seen from the test results that with the increase of the T531 and Irgamet 39 concentration ratio, the DC resistance of the insulating oil after the corrosion test first decreases slowly and then decreases rapidly. When the T531 and Irgamet 39 concentration ratio is less than 0.5, the DC resistivity of the insulating oil is relatively high, all greater than 160×10 9 Ω·m, indicating that T531 and Irgamet 39 within this range can effectively inhibit the oil-sulfur corrosion of copper windings without causing a decrease in DC resistivity. When the ratio of T531 to Irgamet 39 is 1:10, the DC resistivity of the insulating oil is the highest, which is 175.96×10 9 Ω·m, when the ratio of T531 to Irgamet 39 is 10:10, the DC resistivity of insulating oil is the lowest, which is 94.80×10 9 Ω·m.

[0027] Figure 5The test results of the acid value of insulating oil after corrosion test under different T531 and Irgamet 39 concentration ratios are shown in the figure. From the test results, it can be seen that with the increase of the concentration ratio of T531 and Irgamet 39, the acid value of the insulating oil after the corrosion test first rises slowly and then rises rapidly. When the concentration ratio of T531 and Irgamet 39 is less than 0.5, the acid value of the insulating oil is low, all less than 0.016 mgKOH / g. The presence of Irgamet 39 can inhibit the production of small molecular organic acids in the insulating oil during the corrosion experiment. When the content of Irgamet 39 gradually decreases, the inhibition effect weakens and the acid value rises. Among them, when the ratio of T531 and Irgamet 39 is 1:10, the acid value of the insulating oil is the lowest, which is 0.0135 mgKOH / g. When the ratio of T531 and Irgamet 39 is 10:10, the acid value of the insulating oil is the highest, which is 0.0314 mgKOH / g.

[0028] The above description is only a preferred embodiment of the present invention. It should be pointed out that a person skilled in the art can make several modifications and improvements without departing from the inventive concept, which all belong to the protection scope of the present invention.

Claims

1. A method for inhibiting oil-sulfur corrosion of oil-immersed power equipment, characterized in that: Antioxidant T531 and metal passivator Irgamet 39 are added to the transformer insulating oil, and the concentration ratio of T531 and Irgamet 39 is controlled to be less than 0.

5.

2. The method for inhibiting oil-sulfur corrosion of oil-immersed power equipment according to claim 1, characterized in that: The concentration ratio of T531 to Irgamet 39 is 0.1-0.

5.

3. The method for inhibiting oil-sulfur corrosion of oil-immersed power equipment according to claim 1, characterized in that: The total amount of antioxidant T531 and metal passivator Irgamet 39 added to each kilogram of transformer insulating oil is 80 to 120 mg.

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