JP5452268B2 - Grease oil fraction measurement method - Google Patents

Description

  The present invention relates to a method for measuring the oil content of a grease to be evaluated, for example, a method for measuring the oil content of grease used in gas-insulated electrical equipment such as a gas-insulated switchgear (GIS). .

  A gas insulated switchgear is constructed by storing devices such as circuit breakers and disconnectors in a metal container filled with an insulating gas, and slides to turn on and off a large current of several hundred to several thousand A It has a contact part and a machine sliding part. In addition, in a gas insulated switchgear, in order to quickly cut a large current in the event of an accident, etc., the electrical contact part and the mechanical sliding part connected to it must operate at a specified speed, improving sliding lubricity. For this reason, grease is applied to the sliding surface.

  Since grease evaporates over time, the lubrication performance decreases with age, and it is generally said that lubrication becomes poor when the oil content is 50% or less. When the oil content decreases and the grease hardens, the friction coefficient increases, the contact part and the sliding part do not operate at the specified speed, and the metal contact increases due to roughening of the sliding surface (seizure). If this occurs, it may lead to a failure to cut off a large current and cause a serious accident such as a ground fault. Therefore, it is particularly important to determine the degree of deterioration by measuring the oil content of grease in aged equipment.

  The oil content of the grease is generally determined by utilizing the property that the base oil of the grease dissolves in the solvent and the thickener of the grease does not dissolve in the solvent. Specifically, the grease is dissolved in a solvent and filtered through filter paper to separate it into base oil and thickener, and the solvent is removed from the filtered solution by evaporation to extract the base oil. Obtain the oil fraction as the mass ratio of the base oil. In this method, the mass of the sample needs several hundred grams.

  However, in the electrical contact portion, the grease, which is an insulator, hinders energization, and therefore the grease is applied as thin as several μm, so the mass of the grease collected as a sample is only a few mg. Further, since the sliding surface of the machine sliding portion also has sliding resistance, only a few hundred mg of grease is applied at most. Therefore, it is not possible to collect a sample that can apply the method of extracting base oil with a solvent.

  Thus, for example, Non-Patent Document 1 introduces a grease deterioration determination method by infrared spectroscopic analysis. Since the sample mass required for infrared spectroscopic analysis is several mg, sufficient measurement is possible even with the amount of sample collected from the instrument. Moreover, there exists the method (patent document 1, patent document 2) which calculates | requires from the light absorbency value as a degradation degree evaluation method of grease.

JP-A 63-263451 JP-A 63-53445

Electric Joint Research, Vol. 52, No. 1, pp. 117-118.

However, in the method of Non-Patent Document 1, only the comparison of the absorbance ratio between the base oil and the thickener is performed, and only by determining whether or not the oil content is reduced compared to the new grease, the oil content is quantitatively determined. There was a problem that the rate could not be obtained and it could not be judged whether or not the poor lubrication range was reached. In addition, in the method of Patent Document 1 described above, although quantitative evaluation is performed, since the evaluation is performed only with the absorbance at 3500 cm ⁻¹ caused by the base oil, the amount of grease to be evaluated provided to the measuring instrument is It is necessary to make it constant. In particular, since a wear material is usually mixed in the grease to be evaluated, there is a problem that a method of making the mass constant cannot be used, and a device is required to make the amount of the grease to be evaluated constant. Moreover, in the method of Patent Document 2, although the above problem is solved by adopting a method of taking the ratio of the absorbance of the absorption peak caused by the base oil and the absorbance of the absorption peak caused by the thickener, The apparatus of Patent Document 2 measures the consistency representing the hardness of the grease to be evaluated, and therefore has a problem that it is difficult to accurately measure the oil content.

  The present invention has been made to solve the above-described problem, and provides a grease oil fraction measuring method capable of accurately and simply measuring the oil fraction even when a small amount of the grease to be evaluated is collected. For the purpose.

  In order to solve the above-described problems and achieve the object, the grease oil fraction measuring method according to the present invention is a grease oil fraction measuring method for measuring the oil fraction of a grease to be evaluated including a base oil and a thickener. The step of producing a deteriorated grease in which the oil content is forcibly reduced from the same type of grease as the evaluated grease, the oil content rate of the deteriorated grease is measured, and the oil content decrease rate is calculated from the oil content rate, A step of measuring an absorbance spectrum of the deteriorated grease using infrared spectroscopy, and obtaining an absorbance ratio, which is a ratio of the absorbance at the absorption peak of the base oil and the absorbance at the absorption peak of the thickener, from the absorbance spectrum And the relationship between the oil reduction rate obtained for the deteriorated grease and the absorbance ratio, and the oil reduction rate of the grease to be evaluated and its The step of obtaining a calibration curve representing the relationship with the luminous intensity ratio, the step of collecting the grease to be evaluated, and measuring the absorbance spectrum of the grease to be evaluated using the infrared spectroscopy, and based on the absorbance spectrum, the base After determining the absorbance ratio, which is the ratio of the absorbance at the absorption peak of oil to the absorbance at the absorption peak of the thickener, an oil content reduction rate corresponding to this absorbance ratio is determined based on the calibration curve, and this oil content reduction rate Calculating the oil content of the grease to be evaluated.

  According to the present invention, there is an effect that the oil content can be accurately and simply measured even when the amount of the grease to be evaluated collected is small.

FIG. 1 is a diagram showing an example of a calibration curve in the first embodiment. FIG. 2 is a diagram showing an apparatus configuration for producing the deteriorated grease in the first embodiment. FIG. 3 is a diagram showing an apparatus configuration for producing deteriorated grease in the second embodiment. FIG. 4 is a diagram showing an apparatus configuration for producing deteriorated grease in the third embodiment. FIG. 5 is a diagram illustrating an example of a change with time of the oil content reduction rate.

  Embodiments of a grease oil fraction measuring method 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.
In the present embodiment, for example, a method for measuring the oil content of a grease used in a gas-insulated electrical apparatus such as a gas-insulated switchgear (GIS) as an evaluation grease will be described.

  The GIS contains devices such as circuit breakers and disconnectors, and has sliding contact parts and mechanical sliding parts for turning on and off a large current of several hundred to several thousand A, and lubricates them. Different types of grease are used depending on the purpose. Specifically, lithium grease, Benton grease, fluorine grease, and urea grease are mainly used. The grease is generally a semi-solid lubricant containing a base oil (liquid lubricant) and a thickener.

  In this embodiment, infrared spectroscopy is used. Infrared spectroscopic analysis is generally used for qualitative analysis by utilizing selective absorption of light having a wavelength specific to a chemical bond in a substance when the substance is irradiated with infrared rays. However, since the amount of absorbed light is proportional to the chemical bond concentration, it is possible to quantitatively analyze the grease oil fraction from the amount of light absorbed at a wavelength corresponding to the chemical bond contained in the grease base oil. .

First, the principle of quantitative analysis using infrared spectroscopy will be described. In the infrared spectroscopic analysis method, for example, the absorbance of grease is measured by a known infrared spectroscopic analyzer (FT-IR: Fourier transform infrared spectrophotometer). Specifically, grease is applied to, for example, a potassium bromide (KBr) plate that does not absorb in the infrared region of 400 to 4000 cm ⁻¹ and used for the apparatus. A spectrum is obtained.

For example, in the case of an infrared spectroscopic spectrum of lithium grease, what is characteristic is an absorption peak derived from CH ₂ peculiar to base oil at a wave number of 1460 cm ⁻¹ , and LiCOO peculiar to a thickener lithium soap at a wave number of 1576 cm ⁻¹ . It is an absorption peak derived from-.

すなわち、吸光度Ａは、レファレンスの透過光の強さＩ_０とサンプル測定時の透過光の強さＩとの比に基づいて得られるとともに、その値は、吸収体の（モル吸光）係数εとモル濃度ｃと吸収（試料）層の厚さｄとの積に等しい。このように、吸光度Ａは、モル濃度ｃ、すなわち、試料（サンプル）濃度に比例している。したがって、基油が減少すると、基油に起因する吸収ピーク（１４６０ｃｍ^-1）の吸光度が小さくなっていく。しかし、式（１）は吸収（試料）層の厚さｄにも依存するため、吸光度を比較する際にはサンプル厚さを一定にして比較する必要がある。そこで、劣化に関与しないピーク、例えば、増ちょう剤に起因する吸収ピーク（１５７６ｃｍ^-1）の吸光度を基準として、基油の吸光度Ａ_２と増ちょう剤の吸光度Ａ_１との比である吸光度比Ａ_２／Ａ_１を用いることにより、下記の式（２）に示すように、試料層の厚さに関係なく、油分の比較ができる。 Here, the absorbance is represented by the following formula (1).

That is, the absorbance A is obtained based on the ratio of the transmitted light intensity I ₀ of the reference and the transmitted light intensity I at the time of sample measurement, and the value is expressed by the (molar absorption) coefficient ε of the absorber. Equivalent to the product of the molar concentration c and the absorption (sample) layer thickness d. Thus, the absorbance A is proportional to the molar concentration c, that is, the sample (sample) concentration. Therefore, when the base oil decreases, the absorbance at the absorption peak (1460 cm ⁻¹ ) due to the base oil decreases. However, since the equation (1) also depends on the thickness d of the absorption (sample) layer, it is necessary to make the comparison with a constant sample thickness when comparing the absorbance. Therefore, the peak which is not involved in the degradation, for example, based on the absorbance of the absorption peak (1576cm ^-1) attributable to the thickener, the absorbance ratio is the ratio between the absorbance A ₁ base oil absorbance A ₂ and thickener By using A ₂ / A ₁ , the oil content can be compared regardless of the thickness of the sample layer, as shown in the following formula (2).

  Next, the grease oil fraction measuring method according to this embodiment will be described. First, a deteriorated grease that is used for a sliding contact portion of a gas-insulated switchgear and the like and forcibly reduces the oil content from the same type of grease as the grease to be evaluated whose grease oil content is to be measured is prepared. That is, a new grease of the same type as that used for the sliding contact portion or the like is prepared, and a deteriorated grease having a reduced oil content is produced by forcibly removing the oil from the new grease. A specific method for producing the deteriorated grease will be described later.

Subsequently, the oil content of the produced deteriorated grease is measured, and the oil content reduction rate is calculated from the oil content. The oil content can be measured by, for example, dissolving degraded grease in a solvent and filtering it with filter paper to separate it into base oil and thickener, and evaporating and removing the solvent from the filtered solution to extract the base oil. It can be determined as the mass ratio (% by weight) of the base oil to the mass of the grease. Moreover, the calculation method of an oil content reduction rate follows the following formula.

On the other hand, the absorbance spectrum of the prepared degraded grease was measured using the above-described infrared spectroscopy, and the ratio between the absorbance at the absorption peak of the base oil and the absorbance at the absorption peak of the thickener was calculated from the absorbance spectrum. Obtain the absorbance ratio. The procedure for obtaining the absorbance ratio from the absorbance spectrum is as described above, and the absorbance A _{2 at} the absorption peak of the base oil (for example, the absorption peak at a wave number of 1460 cm ⁻¹ ) and the absorption peak of the thickener (for example, the wave number of 1576 cm ^−). determining the absorbance ratio _a 2 / _{a 1} is the ratio between the absorbance _{a 1} in the ^first absorption peak).

Next, using the relationship between the oil content reduction rate and the absorbance ratio obtained for the deteriorated grease, a calibration curve representing the relationship between the oil content reduction rate of the grease to be evaluated and its absorbance ratio is obtained. FIG. 1 is a diagram illustrating an example of a calibration curve in the present embodiment, where the horizontal axis represents the oil content reduction rate [weight (wt.)%], And the vertical axis represents the absorbance ratio. In FIG. 1, P ₀ indicates the absorbance ratio when the oil content reduction rate is 0, and represents the absorbance ratio (absorbance ratio at the initial use) of a new grease. P _{1 to} P ₃ indicate the results of measuring the absorbance ratio for a plurality of deteriorated greases having different oil content reduction rates. Moreover, P ₄ is oil reduction rate indicates that the absorbance ratio is 0 in the case of 100%. Further, as the above formula (2) shows, the absorbance ratio A ₂ / A ₁ is proportional to the concentration of the base oil, so that the absorbance ratio A ₂ / A ₁ has a certain slope as the oil decrease rate increases. Decreases linearly. Therefore, as shown in FIG. 1, a calibration curve is obtained by fitting a straight line to P _{0 to} P ₄ . Further, as can be seen from FIG. 1, in order to obtain a calibration curve, data on at least one point of deteriorated grease is required except for P ₀ and P ₄ .

Next, the grease to be evaluated is collected from the sliding contact portion of the gas insulated switchgear. Subsequently, the absorbance spectrum of the grease to be evaluated is measured using the infrared spectroscopic analysis method, and the absorbance ratio is obtained from the absorbance spectrum. The absorbance spectrum can be measured even when a small amount of grease to be evaluated is collected. As described above, the absorbance ratio is the absorbance A _{2 at} the absorption peak of the base oil (for example, the absorption peak at a wave number of 1460 cm ⁻¹ ) and the absorption peak at the absorption peak of the thickener (for example, the absorption peak at a wave number of 1576 cm ⁻¹ ). ₁ (A ₂ / A ₁ ). Then, the oil content reduction rate corresponding to this absorbance ratio (A ₂ / A ₁ ) is obtained based on the calibration curve shown in FIG. 1, and the oil content rate of the grease to be evaluated is calculated from the obtained oil content reduction rate. At this time, the oil content of the new grease is examined in advance by a method using a normal solvent, and the oil content reduction rate obtained based on the calibration curve is subtracted from the oil content at the initial use, thereby obtaining the grease to be evaluated. Oil fraction can be calculated.

  Here, a method for producing deteriorated grease in the present embodiment will be described. FIG. 2 is a diagram showing an apparatus configuration for producing deteriorated grease in the present embodiment. In FIG. 2, the grease 1 of the same product as the grease to be evaluated and the oil absorbing sheet 2 that absorbs the base oil are alternately stacked, and these are pressurized, for example, by placing a weight 4 from above. Further, the entire oil absorbing sheet 2 is put in a heat-resistant container 3 in order to receive the grease 1 protruding by pressurization, and is put in, for example, a thermostatic bath 5 in order to heat them at a predetermined temperature. In this way, the grease 1 of the same product as the grease to be evaluated is disposed between the oil absorbing sheets 2 that absorb the base oil, and the base oil separated from the grease 1 is absorbed by pressurizing and heating the grease 1. A deteriorated grease is produced by removing the sheet 2.

  In FIG. 2, the grease 1 is not only heated but simultaneously pressurized, thereby promoting the base oil removal from the grease 1 and absorbing the base oil (oil component) floating on the grease surface with the oil absorbing sheet 2. Thus, a deteriorated grease is produced in a shorter time than heating alone. Since the oil absorbing sheet 2 needs heat resistance as well as absorbability, polypropylene fiber or polyester fiber is suitable.

  The grease 1 lubricates the sliding surface by releasing the base oil held by the thickener to the sliding surface by pressurization. Therefore, if the property that oil separation by pressurization is easier than evaporation by heating, oil content reduction can be promoted. Further, the larger the pressure of pressurization, the more oil tends to be released, and the magnitude of the pressure can be arbitrarily set by changing the mass of the weight 4.

  The higher the temperature, the easier it will be to release oil, so the higher the temperature, the better the effect, but the set temperature should be below the maximum recommended temperature recommended by the manufacturer, and to prevent alteration such as oxidation. It is desirable not to use as high a temperature as possible.

  FIG. 5 is a diagram illustrating an example of a change with time of the oil content reduction rate. In FIG. 5, when heating is performed at the maximum use temperature of 150 ° C. recommended by the manufacturer and the inside of the thermostatic chamber 5 is evaporated while substituting with nitrogen to prevent oxidation (150 ° C. heating, replacement of nitrogen at 300 cc / min), the temperature is 80 ° C. The time-dependent changes in the oil content reduction rate are shown for the case of heating and placing a 500 g weight (heating at 80 ° C., pressing with a 500 g weight). As can be seen, when the pressure is applied and heated, the oil content can be reduced in a short time despite the low temperature, and the production period of the deteriorated grease can be shortened.

If the deteriorated grease from which oil has been forcibly removed and a new grease are mixed at an arbitrary ratio, the oil content of the deteriorated grease used for the mixing is larger than the oil content of the new grease and smaller than that of the new grease. Degraded grease with oil content can be produced. For example, in FIG. 1, when obtained by the apparatus shown in FIG. 2 degradation grease corresponding to P _3, degradation grease correspond to P _1, P ₂ is a grease degradation grease new corresponding to P ₃ It can be obtained by mixing at a predetermined ratio.

  As described above, according to the present embodiment, even when the amount of grease to be evaluated collected is a very small amount, the oil content can be measured accurately and simply. That is, even if the amount of grease to be evaluated is very small, it is possible to determine the absorbance ratio by measuring the infrared spectrum, and the oil fraction can be calculated with high accuracy from this absorbance ratio and a calibration curve prepared in advance. Can be obtained.

  Further, in the method for producing a deteriorated grease for preparing a calibration curve, not only heating but also pressurizing can accelerate the oil reduction rate and shorten the preparation period of the deteriorated grease. Further, by applying pressure, a deteriorated grease can be obtained in a short period even when the temperature is relatively low. For this reason, deterioration modes other than evaporation, for example, oxidation of grease can be prevented, and there is an effect that more accurate measurement can be performed.

Embodiment 2. FIG.
In the present embodiment, a method different from that in Embodiment 1 will be described as a method for producing deteriorated grease. FIG. 3 is a diagram showing an apparatus configuration for producing deteriorated grease in the present embodiment. In FIG. 3, for example, a plurality of thinly applied greases 1 of the same product as the grease to be evaluated are prepared on a glass plate 6, and these glass plates 6 are placed in a support case 7 provided with a glass plate mounting step. The support case 7 is placed in the thermostat 5 and heated. The thermostat 5 is connected to a nitrogen gas tank 9 provided outside the thermostat 5 via a valve 8. The thermostatic chamber 5 is provided with a discharge port 10 through which gas can be discharged to the outside.

  In FIG. 3, the grease 1 is thinly applied to the glass plate 6 to increase the evaporation area, and the inside of the thermostatic chamber 5 is heated at a predetermined temperature, thereby promoting the evaporation of the base oil of the grease 1. In addition, while heating the thermostatic chamber 5 at a predetermined temperature, in order to prevent oxidation and remove the evaporated base oil, nitrogen gas is flowed from the nitrogen gas tank 9 into the thermostatic chamber 5 to exhaust the evaporated base oil and nitrogen gas. By discharging from the outlet 10, the atmospheric gas in the thermostat 5 is replaced.

  According to the present embodiment, the grease 1 is thinly applied on the glass plate 6 and the evaporation area is increased with respect to the sample mass, thereby accelerating the evaporation of the grease oil and shortening the production period of the deteriorated grease. it can.

  Further, the temperature chamber 5 is filled with nitrogen gas, and the nitrogen gas and evaporated base oil in the temperature chamber 5 are replaced with new nitrogen gas, so that the grease 1 is prevented from being oxidized and the base oil is evaporated. Has a promoting effect.

Embodiment 3 FIG.
In this embodiment, a method different from Embodiments 1 and 2 will be described as a method for producing deteriorated grease. FIG. 4 is a diagram showing an apparatus configuration for producing deteriorated grease in the present embodiment. In FIG. 4, compared with FIG. 3, the thermostatic bath 5 is not provided with the discharge port 10, and a vacuum pump 11 is attached via the valve 8 instead of the nitrogen gas tank 9. 4 is the same as that of FIG. 3, the same components are denoted by the same reference numerals, and detailed description thereof is omitted.

  In the present embodiment, the vacuum pump 11 is attached to the thermostatic chamber 5 via the valve 8 to perform evacuation. When the heating temperature is raised and the evaporation amount of the base oil is increased by evacuating in this way, the effect of removing the evaporated base oil is greater than the replacement with nitrogen gas.

  By immediately removing the evaporated base oil gas of the grease 1 with the vacuum pump 11, the environment in the thermostatic bath 5 is kept below the vapor pressure of the base oil, and the evaporation of the base oil of the grease 1 is promoted. Therefore, it is possible to further shorten the period for preparing a deteriorated sample.

  In FIG. 5, when the maximum use temperature 150 ° C. recommended by the manufacturer is heated and the inside of the thermostatic chamber 5 is evaporated while substituting with nitrogen to prevent oxidation (150 ° C. heating, replacement of nitrogen 300 cc / min), The changes over time in the oil content reduction rate are shown for the case of halving and vacuuming (heating at 150 ° C., thin coating, vacuuming). As can be seen, the oil content can be reduced in a shorter period when the amount of grease applied is reduced and vacuumed. The effect is further improved by further reducing the coating amount.

  According to the present embodiment, not only heating but also evacuation is performed, and the vapor environment is always kept below the vapor pressure of the base oil of grease 1, thereby accelerating the oil evaporation rate and reducing the production time of the deteriorated grease. It can be shortened. Moreover, since the deterioration grease can be prevented from being oxidized by evacuation, there is an effect that measurement with higher accuracy can be performed.

  The present invention is useful as a method for measuring the oil content of grease used in gas-insulated electrical equipment and the like.

DESCRIPTION OF SYMBOLS 1 Grease 2 Oil absorption sheet 3 Heat-resistant container 5 Constant temperature bath 6 Glass plate 7 Support case 8 Valve 9 Nitrogen gas tank 10 Outlet 11 Vacuum pump

Claims (5)

A grease oil fraction measuring method for measuring the oil fraction of a grease to be evaluated containing a base oil and a thickener,
Producing a deteriorated grease in which the oil content is forcibly reduced from the same type of grease as the grease to be evaluated;
The oil content of the deteriorated grease is measured, the oil decrease rate is calculated from the oil content, and the absorbance spectrum of the deteriorated grease is measured using infrared spectroscopy, and the absorption peak of the base oil is calculated from the absorbance spectrum. Obtaining an absorbance ratio which is a ratio of the absorbance at the absorption peak at the absorption peak of the thickener;
Using the relationship between the oil reduction rate and the absorbance ratio determined for the deteriorated grease, obtaining a calibration curve representing the relationship between the oil reduction rate of the grease to be evaluated and its absorbance ratio;
Collecting the grease to be evaluated;
The absorbance spectrum of the grease to be evaluated is measured using the infrared spectroscopy, and the absorbance ratio, which is the ratio between the absorbance at the absorption peak of the base oil and the absorbance at the absorption peak of the thickener, is determined from the absorbance spectrum. After obtaining the oil content reduction rate corresponding to the absorbance ratio based on the calibration curve, and calculating the oil content rate of the grease to be evaluated from the oil content reduction rate;
A method for measuring a grease oil fraction, comprising: In the step of producing the deteriorated grease,
A grease of the same product as the grease to be evaluated is disposed between the oil absorbing sheets that absorb the base oil, and the base oil separated from the grease is removed by the oil absorbing sheet by pressurizing and heating the grease. The grease oil content measuring method according to claim 1, wherein the deteriorated grease is produced by removing the grease. In the step of producing the deteriorated grease,
2. The deteriorated grease is produced by applying a grease of the same product as the grease to be evaluated on a glass plate and heating the grease to evaporate the base oil from the grease. The method for measuring the grease oil fraction described in 1.   The glass plate is disposed in a thermostatic bath, the thermostatic bath is filled with nitrogen gas, and the nitrogen gas and the evaporated base oil in the thermostatic bath are replaced with new nitrogen gas. The grease oil fraction measuring method according to claim 3.   The said glass plate is arrange | positioned in a thermostat, The vacuum environment is evacuated and the vapor | steam environment is kept below the vapor pressure of the said base oil, The grease oil fraction measuring method of Claim 3 characterized by the above-mentioned.

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