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DL/T 1977-2019: Determination of oxidation stability of mineral insulating oil by differential scanning calorimetry (DSC)
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Determination of oxidation stability of mineral insulating oil by differential scanning calorimetry (DSC)
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DL/T 1977-2019
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Basic data | Standard ID | DL/T 1977-2019 (DL/T1977-2019) | | Description (Translated English) | Determination of oxidation stability of mineral insulating oil by differential scanning calorimetry (DSC) | | Sector / Industry | Electricity & Power Industry Standard (Recommended) | | Classification of Chinese Standard | F20 | | Classification of International Standard | 27.100 | | Word Count Estimation | 9,989 | | Date of Issue | 2019-06-04 | | Date of Implementation | 2019-10-01 | | Quoted Standard | GB/T 7597; SH/T 0790-2007 | | Adopted Standard | IEC/TR 62036-2007, MOD | | Issuing agency(ies) | National Energy Administration | | Summary | This standard specifies a method for characterizing the oxidative stability of mineral insulating oils by means of differential scanning calorimetry (DSC), by means of oxygen pressurization and temperature-programmed determination of the oxidative induction period. This standard applies to the determination of the oxidation stability of unused and used mineral insulating oils. | DL/T 1977-2019: Determination of oxidation stability of mineral insulating oil by differential scanning calorimetry (DSC)
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Determination of oxidation stability of mineral insulating oil by differential scanning calorimetry (DSC)
DL/T 996-2019
ICS 27.10
F 20
People's Republic of China Electric Power Industry Standard
Determination of oxidation stability of mineral insulating oil
Differential scanning calorimetry
(IEC /TR 62036..2007, MOD)
2019-06-04 released
2019-10-01 implementation
Issued by National Energy Administration
Table of contents
Foreword...II
1 Scope...1
2 Normative references...1
3 Terms and definitions...1
4 Method summary...1
5 Equipment...2
6 Reagents and materials...2
7 Calibration...2
8 Preparation...3
9 Test Procedure...3
10 Precision...4
11 Report...5
Appendix A...6
Appendix B...7
Foreword
This standard was drafted in accordance with GB/T 1.1-2009.
Please note that certain contents of this document may involve patents. The issuing agency of this document is not responsible for identifying these patents.
The revision of this standard adopts IEC /TR 62036.2007 "Test Method for Oxidation Stability of Mineral Insulating Oil Differential Scanning Calorimetry (DSC)".
This standard is redrafted according to IEC /TR 62036.2007.For the convenience of comparison, this standard and IEC /TR 62036.2007 are given in Appendix A
A list of structural differences. A list of technical differences between this standard and IEC /TR 62036.2007 is given in Appendix B.
This standard was proposed by the China Electricity Council.
This standard is under the jurisdiction of the National Electrochemical Standardization Technical Committee (TC322).
Drafting organization of this standard. State Grid Hunan Electric Power Research Institute;
Participants in this standard. State Grid Zhejiang Electric Power Co., Ltd. Electric Power Research Institute, PetroChina Lanzhou Lubricant Research and Development Center,
State Grid Fujian Electric Power Co., Ltd. Electric Power Research Institute.
The main drafters of this standard. Wu Junjie, Feng Bing, Chen Shaoyi, Wan Tao, Gong Shangkun, Zhou Zhou, Ming Julan, Wang Huijuan, Zheng Dongsheng, Lian
Hongsong, Zhang Qi, Xu Song, Liu Kai, Zeng Huifang, Li Haiyan, Chen Hua, Wei Jiaqiang, Liu Yiyi.
This standard was first issued on the year, month and day.
The opinions or suggestions during the implementation of this standard are fed back to the Standardization Center of the China Electricity Council (Baiguang Road, Beijing
No. 100761).
Determination of oxidation stability of mineral insulating oils. Differential scanning calorimetry
1 Scope
This standard specifies the use of Differential Scanning Calorimetry (DSC) to characterize the mineral insulation through oxygen pressurization and programmed heating to determine the oxidation induction period.
The method of oil oxidation stability.
This standard is applicable to the determination of oxidation stability of unused and used mineral insulating oils.
2 Normative references
The following documents are indispensable for the application of this document. For dated reference documents, only the dated version applies to this document.
For undated references, the latest version (including all amendments) applies to this document.
GB/T 7597 Power oil (transformer oil, steam turbine oil) sampling method
SH/T 0790-2007 Lubricating grease oxidation induction period measurement method (pressure differential scanning calorimetry)
3 Terms and definitions
The following terms and definitions apply to this document.
3.1
Thermal curve
Graph of sample heat flow versus time.
[SH/T 0790-2007, Terms and Definitions 3.4]
3.2
Extrapolated onset time
The time measured on the thermal curve is the time at the intersection of the baseline extrapolation line and the tangent line at the maximum rate of the oxidation exothermic peak.
[SH/T 0790-2007, Terms and Definitions 3.1]
3.3
Oxidation induction time (OIT)
The oxidation rate increases from zero to the maximum rate for a period of time, and its value is consistent with the extrapolated inflection point time.
[SH/T 0790-2007, Terms and Definitions 3.2]
4 Method summary
Weigh a certain quality of mineral insulating oil sample, put it into the differential scanning calorimeter test cell, pass the program under the specified oxygen pressure
The temperature rise control causes the sample to undergo an oxidative exothermic reaction, and the extrapolated inflection point time of the oxidation exothermic peak on the thermal curve is measured and recorded as the oxidation induction period.
Characterize the oxidation stability of mineral insulating oil.
5 Equipment
5.1 Differential scanning calorimeter. It can maintain the pressure above 2.0 MPa, control the heating rate from 0 ℃/min to 20 ℃/min and keep it constant
Temperature, and can automatically record the heat flow difference between the sample and the blank according to the required sensitivity and deviation.
5.2 Sample pan and reference pan. flat-bottomed aluminum pan for differential scanning calorimeter.
5.3 Sample transfer device. a clean and inert device that can transfer the sample to the sample pan. It is advisable to use a glass rod with a diameter of 3 mm to 4 mm.
Platinum wire with a diameter of 0.25 mm, disposable pipette or disposable syringe needle, etc.
5.4 Oven. can be heated and kept constant at 120 ℃ ± 5 ℃.
5.5 Analytical balance. Sensitivity is 0.1 mg.
5.6 Desiccator. a desiccator that can dry and preserve the sample pan and reference pan.
6 Reagents and materials
6.1 Petroleum ether. analytically pure, boiling range 60 ℃ ~ 90 ℃.
6.2 Acetone. analytically pure.
6.3 Oxygen. the purity is not less than 99.5% (volume fraction).
6.4 Indium. the purity is not less than 99.9% (mass fraction), used as a calibration standard.
7 Calibration
7.1 Temperature calibration
7.1.1 Calibrate with indium under normal pressure and air atmosphere. The calibration should be performed once a month. If the equipment is not used frequently, it should
calibration.
7.1.2 Weigh about 10 mg of indium from the sample pan into the sample cell, put the reference pan into the reference cell, close the test cell, and turn on the differential display
The scanning calorimeter is heated from room temperature to 180 ℃ at a heating rate of 10 ℃/min. After the operation is completed, the measured indium melting point temperature should be
156.6 ℃±0.3 ℃.
7.1.3 If the melting point temperature deviates from this value, it should be calibrated in accordance with the hardware or software calibration procedures in the manufacturer's instrument manual.
7.2 Temperature controller calibration
7.2.1 The temperature controller calibration should be carried out once a year.
7.2.2 The calibration procedure is to leave the sample pan and reference pan in the test cell, close the test cell, slowly open the oxygen pressure to 2.0 MPa ± 0.1 MPa,
Turn on the differential scanning calorimeter to heat up and keep the test cell at the selected test temperature (130 ℃, 160 ℃, 210 ℃). After 10 minutes,
If the difference between the displayed temperature and the selected temperature exceeds ±0.5 ℃, the temperature controller should be adjusted until it meets the requirements. After adjustment, continue to the next step
Wait at least 5 minutes to verify that the temperature is stable.
7.2.2 If the instrument does not have a temperature controller adjustment function, the calibration of the temperature controller should be carried out according to the recommendations of the instrument manufacturer.
7.3 Calibration of test cell pressure gauge
7.3.1 The pressure gauge should be calibrated every two years.
7.3.2 A calibrated pressure transducer or a pre-calibrated measuring tool shall be used, and the calibration shall be carried out according to the operation manual of the instrument test cell.
7.3.3 It should be ensured that the error of the pressure gauge does not exceed ±2%, otherwise a qualified pressure gauge should be replaced.
8 Preparation
8.1 Sample pan pretreatment. Rotate and clean the sample pan in a beaker containing petroleum ether and acetone, and then put it in an oven at 120 ℃
Dry, and finally put the sample pan into the desiccator. All pretreatment operations should be completed with clean tweezers and avoid mechanical damage to the sample pan.
8.2 Instrument preparation. The instrument should be calibrated according to the requirements of Chapter 7.
8.3 Samples. The collection, transportation and storage of samples should comply with the requirements of GB/T 7597.
9 Test steps
9.1 Check the sample pan and reference pan. If there is contamination, oxidation or mechanical damage, replace it with a new one.
9.2 Using a sample transfer device, weigh 4 mg ± 0.2 mg of sample in the pre-processed sample pan. The sample should be evenly spread on the bottom of the pan.
On the surface, avoid contaminating the inside and outside of the tray.
9.3 Check the differential scanning calorimeter test cell to ensure that the temperature is below 30 ℃, use tweezers to put the sample pan into the sample cell, and put the reference pan into the
In the reference cell, then close the test cell and pressure relief valve.
9.4 Heat the test cell to 30 ℃ and open the oxygen inlet valve to fill with oxygen, keep the pressure at 2.0 MPa ± 0.1 MPa, and use the outlet valve
Adjust the oxygen flow rate to 60 mL/min±10 mL/min and keep it for 5 minutes. If the pressure is unstable, restart the test.
9.5 The temperature rise of the test program is shown in Figure 1.The specific steps are as follows.
9.6 After the heating program is over, close the oxygen inlet valve, open the test cell pressure release valve, slowly release the test cell pressure and cool to room temperature.
9.7 According to the thermal curve given by the instrument, measure the extrapolated inflection point time from the temperature rise from 30 ℃ to the oxidation exotherm, accurate to 0.1 min.
It is the oxidation induction period of the sample. The typical thermal curve and oxidation induction period (OIT) of the sample are shown in Figure 2.
10 Precision
10.1 Repeatability.
Repeatability standard deviation. Sr=2.7 min
-Within the 95% confidence interval, the difference between the two results of repeated determinations of the same sample under the same conditions by the same operator with the same instrument
Should be less than the repeatability limit (Sr)
10.2 Reproducibility
Standard deviation of reproducibility. SR=5.8 min
-Within the 95% confidence interval, the difference between the two results of the same sample measured by different laboratories and different operators with different instruments
Less than the reproducibility limit (SR)
11 Report
11.1 Take the arithmetic average of the results of two repeated determinations as the measured value.
11.2 Report the oxidation induction period of the sample to the nearest 0.1 min.
Appendix A
(Informative appendix)
The chapter numbering of this standard is compared with that of IEC /TR 62036.2007.
Table A.1 gives a list of the structural differences between the chapter numbers of this standard and IEC /TR 62036.2007.
Appendix B
(Informative appendix)
Technical differences between this standard and IEC /TR 62036.2007 and the reasons
Table B.1 gives a list of technical differences between this standard and IEC /TR 62036.2007 and the reasons
Table D.1 Technical differences between this standard and IEC /TR 62036.2007 and the reasons
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