JP4994899B2 - Flow electrification diagnosis method for oil-filled electrical equipment - Google Patents

Description

  The present invention relates to a method for diagnosing fluid charge generated by the flow of insulating oil used in oil-filled electrical equipment, and a method for suppressing fluid charge.

  The fluid electrification phenomenon that occurs in oil-filled electrical equipment such as transformers is due to the fact that an insulating liquid such as electrical insulating oil (hereinafter referred to as insulating oil) used for insulation and cooling contacts a solid insulator such as insulating paper. This is an electrostatic phenomenon that occurs when the charging progresses, and when charging progresses, internal discharge may occur, which may lead to malfunction of the electrical equipment.

  Conventionally, as described in Non-Patent Document 1, as a technique for diagnosing fluid charging, a technique for measuring winding leakage current and diagnosing the fluid charging characteristics of a transformer, and the charge degree or dielectric loss tangent of insulating oil A method for diagnosing charging characteristics such as has been used.

  The measurement of the winding leakage current of the transformer is described on pages 142 to 144 of Non-Patent Document 1. When the insulating oil flows through the transformer, the solid insulator is generally negatively charged and the insulating oil is positively charged. When insulating oil is circulated with a specified number of pumps, the current flowing into the neutral point of the high-voltage winding is measured, and the winding leakage current is measured from the magnitude of the measured current to evaluate the soundness of the transformer. To do. However, this method has a problem that the measurement cannot be performed unless the transformer is stopped.

  As for the method for measuring the charge degree of the insulating oil, a plurality of methods are described on pages 133 to 142 of Non-Patent Document 1, and one of them is a measurement method using a mini electrostatic tester. In the measurement of the degree of charge using a mini electrostatic tester, a certain amount of sample oil is passed through a paper filter. At this time, the current generated in the static electricity generation part or the current flowing into the Faraday cage is measured, and the magnitude of the measurement current is measured. Therefore, the degree of charge of insulating oil is evaluated. In general, the degree of charge is often evaluated by the amount of charge obtained by dividing the current by the flow rate of the sample oil per unit time.

  In general, the charge of new oil is lower than that of aged oil. For example, Non-Patent Document 1, page 148, Fig. 7-3-11 shows a tendency of the charging degree of insulating oil to increase over time. Further, there are specified a management value of the charging degree of the insulating oil at the time of installation of the transformer as 200 pC / ml, and a charging value of the insulating oil during the operation of the transformer as 500 pC / ml, respectively. The reason why the degree of charge of the new oil is low and the degree of charge increases with the passage of years is considered to be because some component in the insulating oil is altered.

  Therefore, as a method of diagnosing fluid charge by focusing on a specific component contained in insulating oil and grasping a product generated by oxidation or the like of the specific component, Patent Document 1 discloses a method for diagnosing fluid charge in oil such as a sulfur compound. A flow charge diagnostic method focusing on trace components is described. That is, Patent Document 1 discloses a conventional technique including the following contents. (1) Sulfur compounds, nitrogen compounds, oxidation reaction products of sulfur compounds, oxidation reaction products of nitrogen compounds, and their metal complexes, which are present in insulating oil in oil-filled electrical equipment, are collected as indicators. The current level of flow chargeability is diagnosed by comparing the content of each indicator substance detected from the insulating oil with the degree of charge according to the content of each indicator substance investigated in advance. (2) Flow electrification is suppressed by adding benzotriazole (BTA) and ditertiary butylparacresol (DBPC) to an insulating oil containing a sulfur compound or the like. (3) Flow charging is suppressed by adding at least one of indole nitrogen compounds, carbazole nitrogen compounds, and quinoline nitrogen compounds to an insulating oil containing a sulfur compound or the like. (4) The sulfur compound described in (1) is adsorbed and removed to suppress the flow charge.

JP-A-2005-223104 Electric Cooperative Research, Vol. 54, No. 5 (Part 1), “Maintenance management of oil-filled transformers” by Electric Power Transformer Maintenance Management Committee, Electric Joint Research Society, February 25, 1999 Issue

  However, according to the above conventional technique, there are the following problems. In the conventional flow charge diagnostic method, as described in Non-Patent Document 1, the most frequently used method is to collect oil from an oil-filled electrical device that is actually operating and measure the degree of charge. This is to evaluate the current charge degree, and the future trend of the charge degree has not been studied.

  In addition, in the attempt to examine the charge degree from a trace amount component in the insulating oil described in Patent Document 1, it is for evaluating the current charge degree, and the future trend of the charge degree will be examined. There wasn't.

  Further, the conventional method for suppressing fluid charge is based on a test in which a substance for suppressing fluid charge is added to insulating oil, and has not been studied in the presence of a cellulose insulator. Cellulose insulators are used, for example, as insulating paper covering the conductor surfaces of windings in oil-filled transformers. As described above, under the condition that the cellulose insulator coexists, there is a problem that the charge degree may increase depending on the condition even if the substance has the effect of suppressing the flow charge in the absence of the cellulose insulator. there were.

  The present invention has been made in view of the above, and predicts changes and trends in trace components contained in insulating oil in oil-filled electrical equipment, thereby diagnosing future trends in charging characteristics associated therewith, and An object of the present invention is to obtain a fluid charge diagnostic method and a fluid charge suppression method for oil-filled electrical equipment that can suppress an increase in the degree of charge by controlling trace components.

In order to solve the above-described problems and achieve the object, the flow charging diagnostic method for oil-filled electrical equipment according to the present invention is a method for diagnosing the flow chargeability of an oil-filled electrical equipment filled with insulating oil. The concentration of the sulfur compound contained in the insulating oil and the concentration of the sulfur oxide that is an oxide of the sulfur compound are respectively measured, and the sulfur oxide concentration and (sulfur oxide concentration) / (sulfur compound concentration + Based on the relationship at a certain point in time with the sulfur oxide concentration), the charging characteristics of the insulating oil are evaluated and the future prediction of the change with time is performed.

  According to the present invention, it is possible to predict the future trend of the degree of charging from the amount of sulfur compound contained in the insulating oil in the oil-filled electrical device, and to effectively suppress the flow charge.

  Embodiments of a fluid charging diagnostic method and a fluid charging suppression method for oil-filled electrical equipment according to the present invention will be described below in detail with reference to the drawings. Note that the present invention is not limited to the embodiments.

Embodiment 1 FIG.
FIG. 1 is a diagram showing a sulfur compound assumed to be contained in the insulating oil to which the present embodiment is applied and its charging characteristics. In FIG. 1, sulfides (R ₁ —S—R ₂ ) that are considered to have the greatest effect on the increase in the charging degree of insulating oil, and various sulfurs that are generated from sulfide as a starting material and are considered to exist in insulating oil. Compounds are shown.

Sulfoxide (R ₁ —SO—R ₂ ), which is considered to be a key substance for increasing the degree of charge, is assumed to increase over time up to a certain concentration, but may change to another substance over time. .

As will be described later, another substance that is changed from sulfoxide at present is assumed to be sulfonium ion (R ₁ —SOH ⁺ —R ₂ ) in which cation incorporates a cation in the molecule or sulfone that is considered to be inactive. (R ₁ —SO ₂ —R ₂ ) or a sulfonic acid (R ₁ —SO ₃ H) in which the insulating oil exhibits negative chargeability is assumed. Further, in FIG. 1, the change from sulfoxide to sulfonium ion is indicated by a dotted arrow, unlike the others, but this is actually isolated although the sulfonium ion is assumed as an actual highly charged substance. This means that it is difficult to perform quantitative analysis. In addition, the presence of copper, which is a conductive material such as a coil, causes sulfide or sulfonium ions to bond with copper to form copper complexes of sulfide or sulfonium, and these copper complexes are present in the insulating oil, affecting the charge level. It is thought that it exerts.

  The sulfide contained in the insulating oil is contained in almost all brands (at least all brands of insulating oil refined domestically) as having an action of suppressing oxidative degradation. The amount varies depending on the brand.

  FIG. 2 is a graph showing the relationship between the change with time of the sulfur compound and the degree of charge when the initial sulfide concentration is high. FIG. 3 is a graph showing the relationship between the change with time of the sulfur compound and the degree of charge when the initial sulfide concentration is low.

  In FIG. 2, the sulfide concentration in stage 1 is 3000 ppm. This is an example of a case where the initial sulfide concentration is high, and it is considered that sulfide as a resource to be converted into sulfoxide is sufficiently retained. Therefore, it is considered that there is a sufficient potential to increase the charging degree, sulfoxide is generated from sulfide, and the charging degree increases as the concentration of sulfoxide increases. Note that the degree of charging that is assumed to increase over time is indicated by a curve with an arrow (in this case, a substantially straight line). Moreover, as the step proceeds, sulfonic acid is produced from the produced sulfoxide.

  On the other hand, in FIG. 3, the initial sulfide concentration is 500 ppm, which is 1/6 of the case of FIG. As shown in FIG. 3, the concentration of sulfoxide is increased until the middle stage, but in the latter half of the stage (after stage 4), the amount of sulfide that can be supplied decreases, and the conversion from sulfoxide to sulfonic acid also occurs at the same time. It is thought that the concentration starts to decrease from a certain stage. Therefore, it is presumed that the degree of charging does not increase greatly, but decreases after reaching a certain level. Note that the degree of electrification that initially increases and then reaches a certain level and then decreases is indicated by a curve with an arrow.

  Since sulfoxide has a correlation with the degree of charge, the concentration of sulfoxide gives an indication of the degree of charge of the insulating oil at the time the concentration is measured. Sulfide is a raw material that produces sulfoxide. Therefore, even if the amount of sulfoxide is small, if the amount of sulfide is large, there is a possibility that the degree of charging will further increase in the future. 2 and 3, when a certain amount of sulfoxide is generated in the insulating oil, the sulfoxide concentration / (sulfide concentration + sulfoxide concentration) in FIG. 2 is (sulfoxide concentration) / (sulfide in FIG. 3). (Concentration + sulfoxide concentration). For example, in stage 2 of FIG. 2, the sulfoxide concentration is about 200 ppm and (sulfoxide concentration) / (sulfide concentration + sulfoxide concentration) = 200/3000 = 0.067, whereas FIG. 4, the concentration of sulfoxide is about 200 ppm, and (sulfoxide concentration) / (sulfide concentration + sulfoxide concentration) = 200/450 = 0.44. As described above, in FIG. 2, the charging degree is predicted to increase after stage 2, but in FIG. 3, the charging degree is predicted to decrease after stage 4. Therefore, by examining (sulfoxide concentration) / (sulfide concentration + sulfoxide concentration), it becomes possible to determine whether or not the degree of charge will further increase in the future.

  Based on the trends shown in FIG. 2 and FIG. 3, the states related to the charging characteristics of insulating oil are classified into five regions based on sulfoxide concentration and (sulfoxide concentration) / (sulfide concentration + sulfoxide concentration). Is FIG. In FIG. 4, the horizontal axis represents the sulfoxide concentration in oil (ppm), and the vertical axis represents (the sulfoxide concentration in oil) / (the sulfide concentration in oil + the sulfoxide concentration in oil). The prediction of the degree of charging based on FIG. 4 is performed as follows.

  Region I-1 is a low charge region. That is, since the sulfoxide concentration in the insulating oil is low, the charging degree is also low.

  In the area II-1, an increase in the degree of charging is predicted in the future. That is, in the region II-1, the concentration of sulfoxide is higher than that of the region I-1 and the degree of charge is already high, but (sulfide concentration in oil) / (sulfide concentration in oil + sulfoxide concentration in oil) is Since it is as low as 0.4 or less, the amount of sulfide in oil that produces sulfoxide is relatively large, and it is expected that the degree of charging will increase in the future.

  In the area III-1, a decrease in the charging degree is predicted in the future. That is, in region III-1, the concentration of sulfoxide is higher than that of region I-1 and the degree of charge is already high, but (sulfide concentration in oil) / (sulfide concentration in oil + sulfoxide concentration in oil) is Since it is as high as 0.4 or more, the amount of sulfide in oil that produces sulfoxide is relatively small, and if the sulfoxide is converted to sulfonic acid or the like in the future, the degree of charge is expected to decrease.

  In the area IV-1, an increase in charging degree is predicted in the future. That is, in Region IV-1, the concentration of sulfoxide is higher than that of Region II-1 and the degree of charge tends to be higher than that of Region II-1, but (sulfide concentration in oil) / (sulfide concentration in oil + sulfoxide in oil). (Concentration) is as low as 0.4 or less, the amount of sulfide in oil that produces sulfoxide is relatively large, and it is expected that the degree of charge will increase further in the future.

  In the region V-1, a decrease in the degree of charging is predicted in the future. That is, in the region V-1, the concentration of sulfoxide is higher than that of region II-1 and the degree of charging tends to be higher than that of region II-1, but (sulfide concentration in oil) / (sulfide concentration in oil + sulfoxide in oil). (Concentration) is as low as 0.4 or less, so the amount of sulfide in oil that produces sulfoxide is relatively small. In the future, if sulfoxide is converted to sulfonic acid and the like, the degree of charge is expected to decrease. .

  FIG. 5 is a diagram for diagnosing the degree of charging using the relationship between the sulfoxide concentration in oil and the volume resistivity, and is a diagram diagnosing the future trend of the degree of charging from a different perspective than FIG. 4. As shown in FIG. 5, the sulfoxide concentration in oil (ppm) is plotted on the horizontal axis, the volume resistivity (Ωcm, room temperature, 0 minute) is plotted on the vertical axis, and the measurement results are plotted according to the range of charge (pC / ml). ing. As described above, the sulfoxide may be further changed to another substance, and the actual highly charged substance is considered to be, for example, a sulfonium ion, but it is difficult to actually isolate and quantitatively analyze the substance. However, the following conditions are mentioned as a constituent factor of sulfonium ion. That is, there are sulfoxides that take up cations and cations such as protons that are taken up in the oil. Therefore, when the sulfoxide concentration in the insulating oil is high and the amount of cations is large, it is assumed that the degree of charge is easily increased. The sulfoxide in the insulating oil can be confirmed by trace component analysis. The cations (ionic substances) in oil can be estimated from characteristics such as dielectric loss tangent or volume resistivity. Therefore, in FIG. 5, the degree of charge is predicted as follows.

  Region I-2 is a low charge region. That is, the sulfoxide concentration in oil is low and the charge degree is low. Since volume resistivity is high, it is estimated that there are also few cations in oil.

  Since the volume resistivity is low in region II-2, it is estimated that there are many cations in the oil. In the case where the concentration of sulfoxide in oil is high, an increase in charging degree is expected in the future.

  Region III-2 is actually highly charged, and in some cases, further increase in charge is expected in the future. That is, since the sulfoxide concentration in oil is high and the volume resistivity is low, it is estimated that there are many cations present in the insulating oil.

  Region IV-2 is a region where there is no measurement point, but the sulfoxide concentration in oil is high and the degree of charge is high. Since the volume resistivity is high, it is estimated that there are few cations present in the insulating oil.

  In the present embodiment described above, it is necessary to actually measure sulfide, sulfoxide, sulfone and sulfonic acid in the insulating oil. Examples of extraction and analysis include the following methods.

1. Measurement of sulfide in oil Extract sulfide with an adsorbent such as silica gel loaded with metal salt. The sulfide desorbed from the adsorbent is quantified by gas chromatography or liquid chromatography.

2. Measurement of sulfoxide in oil and sulfone in oil Both are polar and are extracted with silica gel. The sulfoxide and sulfone desorbed from the adsorbent are quantified by gas chromatography or liquid chromatography.

3. Measurement of sulfonic acid in oil Since it shows acidity, it is quantified by the color change of an indicator such as alkali blue 6B.

  According to this embodiment, based on the sulfoxide concentration and (sulfoxide concentration) / (sulfoxide concentration + sulfide concentration), it is possible to evaluate the charge degree of the insulating oil and to predict the future change with time. In addition, it is possible to predict changes in the concentration of sulfonium ion, which is one of the causative substances of high charging, by volume resistivity or dielectric loss tangent and sulfoxide concentration. can do.

  In this embodiment, sulfide, sulfoxide, and the like have been described as examples. However, the flow charge according to this embodiment is also applied to other sulfur compounds and sulfur oxides having a similar relationship with respect to the charge characteristics. Diagnostic methods can be applied. Furthermore, as long as the charge characteristics are similar, the present embodiment can be applied not only to sulfur compounds and sulfur oxides but also to other compounds.

Embodiment 2. FIG.
FIG. 6 is a diagram showing the relationship between the operation years of the oil-filled electrical device and the value obtained by multiplying (sulfoxide concentration) / (sulfide concentration + sulfoxide concentration) by the operation years. Hereinafter, (sulfoxide concentration) / (sulfide concentration + sulfoxide concentration) is also referred to as a conversion rate. In the present embodiment, the current state and future trends of the charging characteristics are predicted based on the sulfoxide concentration and the value obtained by multiplying the conversion rate by the number of years of operation.

  As described in the first embodiment, when the insulating oil contains a large amount of sulfide, the sulfoxide increases for a relatively long period of time. As shown in FIG. 6, when the initial sulfide concentration in the insulating oil is 1400 ppm, which is relatively low, the value of conversion rate × operating years has started to decrease since the operating years have passed 30 years. On the other hand, in other cases where the initial sulfide concentration in the insulating oil is higher than 1400 ppm, it continues to increase until the 40 years of operation for which data has been acquired. Further, for example, with respect to the conversion rate × the number of years of operation = 2.0, the number of years of operation in the corresponding plot increases as the initial sulfide concentration increases from 1400 ppm to 5000 ppm. For example, when the initial sulfide concentration is 1400 ppm, the operation period is about 10 years, whereas when the initial sulfide concentration is 5000 ppm, the operation period is about 18 years. This means that when the initial sulfide concentration is 5000 ppm, the conversion rate is smaller and the number of years of operation is longer than when the initial sulfide concentration is 1400 ppm. By considering the operation years, the effect of the operation years that have already passed can be taken into account.

  FIG. 7 is a diagnostic diagram for predicting the current state and future trend of the charging characteristics using the relationship between the sulfoxide concentration and the value obtained by multiplying the conversion rate by the number of years of operation in consideration of the relationship of FIG. The horizontal axis is the sulfoxide concentration in oil (ppm), and the vertical axis is the conversion rate x the number of years of operation, depending on the value of the charge for each of the cases where the copper component is present and absent in the oil. The measurement results are plotted. Diagnosis is performed as follows.

  Region I-3 is a low charge region. That is, the sulfoxide concentration in oil is low.

  In the area II-3, an increase in the charging degree is predicted in the future. That is, the concentration of sulfoxide in oil is also higher than the value in region I-3, while the value of conversion rate x operation years considering operation years is low, so that there is a possibility of increasing the degree of charge. In this region, even if the sulfoxide concentration in the oil is not so high, the conversion rate is low, the operation years are short, or both are satisfied.

  In the area III-3, a decrease in the charging degree is predicted in the future. The range of the sulfoxide concentration in oil in this region is the same as the range of the sulfoxide concentration in oil in Region II-3. On the other hand, the conversion rate × the number of years of operation is a larger value than the fixed value of the sulfoxide concentration in oil. In this region, the conversion rate is high, the operation years are long, or both.

  In the area IV-3, an increase in the charging degree is predicted in the future. That is, since the sulfoxide concentration in oil is also larger than the value in region II-3 and the value of conversion rate × operational years is also small, there is a possibility of increasing the charging degree.

  In the region V-3, a decrease in the charging degree is predicted in the future. In this region, the concentration of sulfoxide in oil is high, but the value of conversion rate x operation years is also large.

  In the present embodiment, based on the sulfoxide concentration in oil and the value obtained by multiplying the conversion rate by the number of years of operation, the degree of charge of the insulating oil can be evaluated and the future prediction of the change with time can be performed.

Embodiment 3 FIG.
In the present embodiment, in the presence of cellulose insulators such as insulating paper used in transformers, etc., the molecular structure, reactivity, ions, etc. of sulfur compounds and oxides of sulfur compounds contained in insulating oil A method of diagnosing the charge degree characteristic based on the dissociation property of the above will be described. In an experiment for confirming the effect of the present invention, it was experimentally confirmed that both a negative charge and a positive charge can be charged to a cellulose insulator. When the insulator is negatively charged, the insulating oil is positively charged. On the other hand, when the insulator is positively charged, the insulating oil is negatively charged.

  As an example of the negative charge of the insulating oil, alkylbenzene added with octyl sulfonic acid can be mentioned. An example of a large positive charge of insulating oil is alkylbenzene heated by adding octyl sulfide or octyl sulfoxide and coexisting with oxygen and a copper catalyst. When the above example is generalized, the following mechanism is assumed.

The main component of the insulating oil is a hydrocarbon, and more specifically, a chain hydrocarbon represented by the chemical formula C _n H _{2n + 2} (paraffin), a saturated cyclic hydrocarbon represented by the chemical formula C _n H _2n (naphthene), and It consists of an aromatic having a benzene ring or a naphthalene ring. The chemical formula C _n H _{2n + 1} is referred to as an alkyl group, a naphthene ring having an alkyl group added thereto is referred to as an alkyl-substituted naphthene, and an aromatic ring having an alkyl group added thereto is referred to as an alkyl-substituted aromatic.

  The molecular weight of the main component of the insulating oil is about 220 to 300. When an alkyl group corresponding to the molecular weight of the insulating oil coexists with components other than the main component of the insulating oil, even if other polar groups are present, it is oleophilic. On the other hand, when the alkyl group is small, the lipophilicity is small, and it is highly possible that the oil does not exist in a uniform state in the oil, for example, as a different phase in the oil or adheres to the container wall.

As mentioned in the above example, when octyl sulfonic acid is added, the insulating oil is negatively charged and the cellulose insulator is positively charged. Octyl sulfonic acid has a molecular weight of 194 and a structure of C ₈ H ₁₆ SO ₃ H. This octyl sulfonic acid dissociates into C ₈ H ₁₆ SO ₃ ⁻ with an ionic formula 193 and H ⁺ with an ionic formula 1. C ₈ H ₁₆ SO ₃ ^— has a large lipophilic alkyl group (in this case, C ₈ H ₁₆ ), and therefore exists stably in oil. On the other hand, H ⁺ has no lipophilic alkyl group and therefore does not exist stably in oil.

  On the other hand, cellulose insulators contain many polar hydroxyl groups in the molecule, and the molecular structure is different from nonpolar insulating oil. In addition, since the molecular structure is not flat, it is affected by steric hindrance and the like, so it is considered that a substance having a large molecular weight is difficult to adsorb.

In the case of the above-mentioned octyl sulfonic acid, it is considered that dissociated H ⁺ is likely to be charged to cellulose from both the polar face and the ionic formula. Therefore, the negative charge is likely to remain in the oil, and the positive charge is likely to be adsorbed on the cellulose insulator, so that the insulating oil is in a relatively large negatively charged state.

Further, as described in the above example, when octyl sulfide is added and heated in the presence of oxygen and a copper catalyst, the insulating oil is positively charged and the insulating paper is negatively charged. Octyl sulfide has a chemical formula of C ₈ H ₁₆ SC ₈ H ₁₆ and has a structure in which alkyl groups are arranged at both ends of a divalent sulfur compound. This divalent sulfur compound has an ability to easily take in oxygen. Therefore, when octyl sulfide is oxidized, it becomes a sulfoxide which is a tetravalent sulfur compound.

  According to the experimental results, the degree of charge of octyl sulfoxide itself is a little higher than that of the alkylbenzene of the base oil, and it cannot be said that it exhibits a markedly high degree of charge. However, when heated in the presence of a copper catalyst or the like, a high degree of charge of about 1 to 2 digits was observed compared to before heating. The following mechanism is assumed for this.

In general, sulfoxides have an action of incorporating H ^{+ and the} like into the molecule and ionizing them, and those incorporating H ^{+ and the} like are referred to as sulfonium ions. In addition, not only H ⁺ but also R ⁺ (R is an alkyl group) and the like are also called sulfonium ions. In the case of octyl, the sulfonium ion has a relatively long alkyl group and thus exhibits a large lipophilicity. In addition, since sulfonium ions have a positive charge, the insulating oil is positively charged, contrary to the case of octyl sulfonic acid. In this case, as a negative charge, a hydroxide ion from which water molecules are dissociated is assumed.

When hydrochloric acid or water is added to an alkylbenzene in which octyl sulfoxide coexists, the charge becomes relatively large. Therefore, octyl sulfoxide takes in H ⁺ dissociated from hydrochloric acid or water to form octyl sulfonium, and has high charge. It was confirmed experimentally that

  When the examples of octyl sulfonic acid, octyl sulfide and octyl sulfoxide described above are studied together, they can be generalized as follows.

In components other than the main component contained in the insulating oil, attention is paid to positively charged ions and negatively charged ions. Then, the molecular weight of the lipophilic group provided for the positively charged ions is compared with the molecular weight of the lipophilic group provided for the negatively charged ions. )> (The molecular weight of the lipophilic group of negatively charged ions), the insulating oil is positively charged. On the other hand, when (the molecular weight of the lipophilic group provided for the negatively charged ions)> (the molecular weight of the lipophilic group provided for the positively charged ions), the insulating oil is negatively charged. In the case where the lipophilic group is not originally provided as in the case of dissociated H ^+, the molecular weight is compared with zero. In the case of (the molecular weight of the lipophilic group included in the positively charged ions) / (the molecular weight of the lipophilic group included in the negatively charged ions) >> 1, a large positive charge is exhibited. When the molecular weight of the oleophilic group included in the ion / (the molecular weight of the oleophilic group included in the negatively charged ion) ≈1, it is hardly charged.

  In addition, when (molecular weight of lipophilic group provided for negatively charged ions) / (molecular weight of lipophilic group provided for positively charged ions) >> 1, a large negative chargeability was exhibited. When the molecular weight of the lipophilic group included in the charged ion / (the molecular weight of the lipophilic group included in the negatively charged ion)> 1, it indicates negative chargeability, and (the parent included in the positively charged ion) When the molecular weight of the oil base) / (the molecular weight of the lipophilic group included in the negatively charged ions) ≈1, it is hardly charged. As described above, the lipophilic group is, for example, an alkyl group.

  Examples of components in oil that have a positive charge in oil include, for example, the above-mentioned sulfonium, a sulfoxide that is a production base of sulfonium, and a positively charged ion such as pyridinium that is a nitrogen compound, and their The basic nitrogen compound which is a production | generation base is mentioned. On the other hand, those having a negative charge in oil include, for example, sulfonic acid, organic acid, non-basic nitrogen compound and the like.

  According to the present embodiment, acidic / basic, dissociation into ions with respect to sulfur compounds and oxides thereof, and nitrogen compounds and oxides thereof, which are components other than the main component in insulating oil. Based on the reactivity and the like, the charge characteristics of the insulating oil can be diagnosed by comparing the molecular weights of the lipophilic groups of the positively charged ions and the negatively charged ions.

Embodiment 4 FIG.

  In general, sulfide compounds and sulfoxide compounds present in insulating oils are aggregates of many compounds with different molecular structures. Therefore, the following estimation can be performed by component analysis of insulating oil using, for example, a gas chromatograph and acquiring a profile including, for example, a sulfide compound and a sulfoxide compound.

  When a sulfide with a constant carbon number is oxidized to produce a sulfoxide, the molecular weight of the sulfoxide increases by 16 relative to the original sulfide. On the other hand, when the oxidation further proceeds to produce sulfone, the molecular weight of sulfoxide increases by 32 relative to the original sulfide. Therefore, when examining the molecular weight distribution of sulfide and sulfoxide, if there is only a difference of 16, the formation of sulfoxide is predicted, and if it is an increase of 32, there is a possibility of proceeding to sulfone.

  In addition, FIG. 8 is a figure which shows an example of the profile of the sulfide and sulfoxide which analyzed using the gas chromatograph. The horizontal axis represents the retention time of the gas chromatograph and is expressed in terms of molecular weight. The vertical axis represents the ratio (frequency) of sulfide or sulfoxide present during the retention time.

  In this way, the molecular weight distribution of the components contained in the insulating oil is measured, and the charging characteristics of the insulating oil are determined based on the molecular weight difference between the sulfur compound identified from the molecular weight distribution and the sulfur oxide that is an oxide thereof. Evaluation can be made. For example, since the transition from sulfide to sulfoxide and sulfone varies depending on conditions such as the number of years of operation, the charging characteristics of insulating oil can be accurately evaluated by considering the ratio of their abundance in addition to the difference in molecular weight. it can.

Embodiment 5 FIG.
In order to suppress the flow electrification, conventionally, addition to an insulating oil such as benzotriazole (BTA) or treatment using an adsorbent such as clay has been studied.

However, the addition of BTA or the treatment using white clay has the following problems. BTA is considered to be effective in adsorbing to the surface of insulating paper and suppressing the transfer of negative charges to the insulating surface. Since the mechanism of fluid charging is considered as described in the third embodiment, the addition of BTA lowers the degree of charge by the action that the insulating oil incorporating the dissociated H ⁺ is negatively charged. In some cases, it is assumed that the effect is lost when H ⁺ is depleted. When white clay is used, the removal of polar substances increases the volume resistivity, makes charge relaxation less likely, and there is a concern about deterioration of charging characteristics due to accumulation of charged charges.

  In the present embodiment, by selecting various types of ion exchange resins or ion exchange membranes, only the ions that affect the high charge degree are removed, thereby suppressing the high charge. Further, by adding a specific ion to the insulating oil and maintaining the balance of the charging characteristics, it is possible to suppress the increase in charging.

Embodiment 6 FIG.
Conventionally, the charging degree has been suppressed by the addition to an insulating oil such as benzotriazole (BTA). And in the state of only insulating oil and BTA, the effect of suppressing the flow charge over a long period can be expected. However, in a system in which a cellulosic insulating material such as a press board coexists, as shown in FIG. 9, an experimental result has been obtained that the degree of charging increases rapidly from a certain time. Therefore, it turned out that there is a problem in the sustainability of the effect of BTA. FIG. 9 is a graph showing the change over time in the degree of charge of alkylbenzene added with octyl sulfoxide when heated in the presence of a copper catalyst and oxygen. The amount of BTA added and the pressboard (PB) A plurality of curves are drawn depending on the presence or absence. The horizontal axis represents the heating time (hr), and the vertical axis represents the charge degree (pC / ml).

  Therefore, when a phenol-based substance is added to insulating oil containing sulfide and sulfoxide, the charge in a system where a press board coexists does not show a large increase in charge as in the case where BTA is added. Confirmed experimentally. In particular, when the molecular weight of the phenol compound is about the same as the molecular weight of the main component of the insulating oil, the effect of suppressing the increase in the degree of charge is more effective. In the present embodiment, in the presence of a press board, a phenol compound whose molecular weight is equivalent to the molecular weight of the main component of the insulating oil is added to the insulating oil containing a sulfur compound such as sulfide and sulfoxide and an oxide of the sulfur compound. This suppresses the charging degree of the insulating oil.

  The action of the phenolic compound having a molecular weight corresponding to the molecular weight of the main component of the insulating oil is that it inhibits the transition to sulfoxide due to oxidation of sulfide, and furthermore, the molecular weight is larger than BTA, It is conceivable that charging is difficult to occur.

  In addition, diagnosis and suppression can be automated by configuring an apparatus using the fluid charging diagnosis method and suppression method described in the first to sixth embodiments.

  As described above, the fluid charging diagnostic method and the fluid charging suppression method for oil-filled electrical equipment according to the present invention include the evaluation of the charging characteristics of insulating oil used in transformers and the like, the prediction of its future trend, and the flow charging. It is useful for effective suppression.

It is a figure which shows the sulfur compound assumed to be contained in the insulating oil to which Embodiment 1 is applied, and its charging characteristic. It is a figure which shows the relationship between a time-dependent change of a sulfur compound, and a charging degree when an initial sulfide density | concentration is high. It is a figure which shows the relationship between a time-dependent change of a sulfur compound, and a charging degree when an initial sulfide density | concentration is high. In Embodiment 1, it is the figure which classified the state regarding the charging characteristic of an insulating oil into five areas by sulfoxide concentration and (sulfoxide concentration) / (sulfoxide concentration + sulfide concentration). It is a figure for diagnosing the degree of charge using the relation between the sulfoxide concentration in oil and the volume resistivity. It is a figure which shows the relationship between the operation years of an oil-filled electrical apparatus, and the value which multiplied the operation years to (sulfoxide concentration) / (sulfide concentration + sulfoxide concentration). In Embodiment 2, it is the diagnostic figure which estimates the present condition and future trend of a charging characteristic using the relationship between the sulfoxide density | concentration and the value which multiplied the conversion rate by the years of operation. It is a figure which shows an example of the profile of the sulfide and the sulfoxide which analyzed using the gas chromatograph. It is the figure which showed the time-dependent change of the charging degree of the alkylbenzene to which octyl sulfoxide was added according to the presence or absence of a press board (PB) and the addition amount of BTA.

Claims (5)

A method of diagnosing the flow chargeability of oil-filled electrical equipment filled with insulating oil inside,
The concentration of the sulfur compound contained in the insulating oil and the concentration of the sulfur oxide that is an oxide of the sulfur compound were measured, respectively, and the sulfur oxide concentration and (sulfur oxide concentration) / (sulfur compound concentration + sulfur oxide) On the basis of the relationship with the concentration) at a certain point of time , the charging characteristics diagnosis method for oil-filled electrical equipment is characterized by evaluating the charging characteristics of the insulating oil and predicting the future of the change with time. A method of diagnosing the flow chargeability of oil-filled electrical equipment filled with insulating oil inside,
The concentration of the sulfur compound contained in the insulating oil and the concentration of the sulfur oxide that is an oxide of the sulfur compound were measured, respectively, and the sulfur oxide concentration and (sulfur oxide concentration) / (sulfur compound concentration + sulfur oxide) Based on the relationship at a certain point in time with (concentration) × (the number of years of operation of the oil-filled electrical device), the evaluation of the charging characteristics of the insulating oil and the future prediction of the change over time are performed. Flow charging diagnostic method.   The fluid charging diagnostic method for oil-filled electrical equipment according to claim 1, wherein the sulfur compound is sulfide, and the sulfur oxide is sulfoxide. A method of diagnosing the flow chargeability of oil-filled electrical equipment filled with insulating oil inside,
Measure the concentration of sulfur oxide contained in the insulating oil and the volume resistivity or dielectric loss tangent of the insulating oil, and based on the relationship between the sulfur oxide concentration and the volume resistivity or dielectric loss tangent at a certain point in time , A fluid charging diagnostic method for oil-filled electrical equipment characterized by evaluating the charging characteristics of oil and predicting future changes with time.   The fluid charging diagnostic method for oil-filled electrical equipment according to claim 4, wherein the sulfur oxide is sulfoxide.

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