JB/T 4279.11-1994 Verification methods for testing instruments and equipment for enameled winding wires Breakdown voltage tester
Some standard content:
Mechanical Industry Standard of the People's Republic of China
Verification Method of Enameled Winding Wire Test Instrument and Equipment Breakdown Voltage Tester
1 Subject Content and Scope of Application
JB/T4279.11-94
Replaces JB4279.11-86
This standard specifies the verification items and technical requirements, verification equipment, verification methods, verification results and processing of enameled wire breakdown voltage tester.
This standard is applicable to the verification of enameled wire breakdown voltage tester (air temperature and high temperature), 2 Reference Standards
JB/T4279.1 Verification Method of Enameled Winding Wire Test Instrument and Equipment General Principles 3 Verification Items and Technical Requirements
3.1 The test voltage of the enameled wire breakdown voltage tester shall not be less than 10000V; the indication error of the test voltage shall be ±3%. 3.2 The test voltage is an AC voltage with a nominal frequency of 50Hz and a waveform close to a sine wave, and the peak factor is within the range of √2±5% (1.34 to 1.48).
3.3 When a current of 5±0.5mA passes through the high-voltage circuit, the tester should send a high-voltage breakdown signal. 3.4 When the test power supply supplies a current of 5±0.5mA, the voltage drop of the test voltage should not be greater than 2%. 3.5 The voltage increase rate of the test voltage should be 100±10V/s, 500±50V/s. 3.6 The rated capacity of the test transformer should be not less than 500VA. The round rod method electrode should be a cylinder with a diameter of 25±0.5mm and a surface roughness Ra of 0.8μm. 3.7
The round rod method load and allowable error should comply with the provisions of Table 1. Table
Error±
The working space temperature deviation of the oven for high temperature test under strong ventilation conditions is ±5℃. 3.92
The safety measures of the tester shall comply with the relevant provisions of high-voltage test equipment, and the test chamber door shall be equipped with a safety interlock device. 3.10
Verification instruments
4.110000/100V voltage transformer, level 0.5. 4.2AC voltmeter, level 0.5.
AC ammeter, level 2.5.
4.4Peak voltmeter and effective value voltmeter, level 2.5. 4.5Oscilloscope.
4.6Stopwatch. Graduation value 0.1%.
Q-1 enameled wire test instrument detector (hereinafter referred to as Q-1 instrument). 4.7
4.8Pan balance, graduation value 0.1g, level ①. Approved by the Ministry of Machinery Industry on December 9, 1994. Implemented on January 1, 199506-01. JB/T4279.11-94. 5.6 Wiring is as shown in Figure 1. When the voltage is 2500V or below, Q-1 meter box 1 is 200kQ. When the voltage is above 2500V, Q-1 meter box I is 800ka. Connect the contacts of the high-voltage vacuum relay, adjust the test voltage to an ammeter reading of 5±0.5mA, and record the voltage U2 at this time. Then disconnect the contacts of the high-voltage vacuum relay, cut off the resistor loop, and record the voltage U2 of the AC voltmeter at this time. Calculate the voltage drop of the test voltage according to formula (4): Where: — voltage drop percentage;
U,-—test voltage, V;
U,-U×100% .
U—Test voltage when the test power source supplies 5mA, V is measured 3 times, and the voltage drop of each test voltage should not be greater than 2%. Figure
Q-1 Instrument
R-resistor; A-ammeter; J-high-voltage vacuum relay T--10000/100V voltage transformer; V—AC voltmeter,) 5.7
Check the rated capacity of the test transformer.
Use a balance to check the error of the load.
5.9Use a caliper to check the diameter of the round rod electrode.
5.10Use a surface roughness comparison sample block to check the surface roughness of the round rod electrode. 5.11Check the temperature deviation of the high-temperature test chamber. (4)
5.11.1The temperature test space of the high-temperature test chamber should include the space occupied by the electrode where the sample is placed and the sample: its interface is parallel to the interface of the space inside the chamber.
5.11.2 Use 9 thermocouples to measure the temperature of 9 measuring points in the measured space. One measuring point is the center point of the measured space, and the other 8 measuring points are the 8 vertices of the measured space. The length of the thermocouple at each measuring point in the test chamber is not less than 300mm. Note: All thermocouples should be calibrated. The 9 thermocouples should be composed of the same spool of wires so that the difference in their mutual potential below 200℃ is not greater than 0.2℃ when converted into temperature difference.
5.11.3 Adjust the temperature of the test chamber so that the temperature of the test chamber does not deviate from the test required temperature by ±2℃. 5.11.4 Start measuring 1 hour after the temperature of the test chamber stabilizes, quickly record the thermoelectric potential of the thermocouples at the 9 measuring points, and measure once every 5 minutes (0th, 5th, 10th, 15th, 20th minutes) to complete 5 measurements. 5.11.5 Calculation of temperature deviation
5.11.5.1 Calculation of spatial temperature deviation
Calculate the average value of the thermoelectric potential of each of the five measurements at the nine measuring points respectively, and convert it into the average temperature of each measuring point by looking up the graduation table. Taking the average temperature of the center point of the measured space as the reference, calculate the spatial temperature deviation (accurate to 0.1°C) between the average temperature of each measuring point and the average temperature of the center point according to formula (5).
aj=[t,-t
Where: a——spatial temperature deviation of the ith vertex of the measured space, i18C;30
JB/T4279.11-94
4.9 Thermocouple, nickel-chromium-copper-nickel (constantan), nickel-chromium-nickel-silicon or other material thermocouple with a wire diameter of 0.5mm and a node diameter of no more than 2.0mm.
4.10 DC digital voltmeter, the allowable measurement error is ±0.05%. When using nickel-copper-copper-nickel (constantan) thermocouple, the resolution of the digital voltmeter shall not be less than 10μV; when using other thermocouples, the resolution of the digital voltmeter shall not be less than 1uV. 4.11 Thermocouple conversion switch.
4.12 Ice bottle.
4.13 Vernier caliper, graduation value 0.02mm. 4.14 Surface roughness comparison sample plate, Ra is 0.8um. 5 Verification method
5.1 Safety inspection. To ensure the safety of operators, the safety measures of the tester shall comply with the relevant regulations on high-voltage test equipment. The test chamber door shall have a safety interlock device.
5.2 Check the test voltage indicating instrument
The primary of the voltage transformer is connected to the high voltage output terminal of the test voltage, and the secondary is connected to the AC voltmeter. For the test instrument with test voltage ranges, the indication values of 200V, 400V, 600V, 800V, and 1000V are checked twice at 1000V and below, the indication values of 500V, 1000V, 1500V, 2000V, and 2500V are checked twice at 2500V, and the indication values of 3000V, 6000V, 8000V, and 10000V are checked twice at above 2500V.
Calculate the indication error according to formula (1):
U. -U
Where: 8—indication voltage relative error, %; U—indication voltage, V;
U—measured voltage, V.
5.3 Measure the peak factor and observe the test voltage waveform (1)
5.3.1 Connect the 8000V terminal of Q-1 instrument box I to the high voltage output terminal of the test power supply. At this time, ground the ground terminal of Q-1 instrument box I and the other end of the high voltage output terminal of the test instrument.
5.3.2 Connect the input terminals of the peak voltmeter and the effective value voltmeter to the 1000V terminal of Q-1 instrument box I and the ground terminal respectively. Note that the input impedance of the voltmeter should be more than 10 times greater than the voltage divider resistance value. 5.3.3 Adjust the test voltage to about 6000V, and calculate the peak factor according to formula (2): PU/U.
Where: — peak value, V;
— effective value, V.
When measuring the peak factor of the test voltage, the peak value factor of the incoming power supply voltage of the breakdown voltage tester should be measured at the same time. 5.3.4 Connect the input terminal of the oscilloscope to the 11000V terminal of the Q-1 instrument box and the ground terminal, observe the voltage waveform, and measure the frequency. 5.4 Use a stopwatch to measure the voltage rise time, and calculate the voltage rise speed according to formula (3): V=60U/t
Where: V-voltage rise speed, V/min;
U-rising voltage, V;
t-time required for voltage rise, s.
Take the average of 3 measurements.
5.5 Connect the AC milliammeter and Q-1 instrument box I in series and then connect them to the high-voltage circuit. Gradually increase the test voltage and check the indication of the ammeter when the tester sends out a breakdown signal. The resistance value of the resistor should be adjusted so that when the test only sends out a breakdown signal, the test voltage is about 1000V, 4000V and 8000V respectively.
JB/T4279.11-94
t:—The average temperature of the ith vertex of the measured space, i=1～8, ℃; t. —The average temperature of the center point of the measured space, ℃. 5.11.5.2 Calculation of time temperature fluctuation
Calculate the difference between the highest temperature and the lowest temperature of the 8 vertices in the measured space in 5 measurements according to formula (6), and obtain the time temperature fluctuation of the measured space (accurate to 0.1℃).
b; bi mxbi miebzxZ.net
Wherein: bi—time temperature fluctuation of the ith vertex, i=1~8,℃; bimas
—highest temperature of the ith vertex, i=1~8,℃; bih-lowest temperature of the ith vertex, i=1~8,℃. 5.11.5.3 Calculation of temperature deviation
The temperature deviation is synthesized by the space temperature deviation and the time temperature fluctuation, and the temperature deviation is calculated according to formula (7) (accurate to 0.1℃). At=(a:+
Wherein: △t;—the i-th temperature deviation, i=1~8,℃; a:—the i-th spatial temperature deviation, i=1~8,℃; b;-—the i-th time temperature fluctuation, i=1～8,℃. 5.11.6 Processing of high temperature test chamber calibration results (6)
Check the calculation results of Article 5.11.5.3 of this standard (keep 1 significant figure). If the maximum temperature deviation meets the requirements of Article 3.9 of this standard, the test space is the working space. 6 Processing of calibration results
6.1 This standard does not include the calibration of the test chamber test temperature indicating instrument (or thermometer). For test chambers where the test temperature is displayed by a temperature indicating instrument and the temperature sensing element of the instrument cannot be located at the center of the working space, the calibration results should give the difference between the temperature indicator value at the calibration temperature and the actual temperature at the center of the working space. Error. 6.2 The instrument for applying voltage is allowed to be separate from the high temperature test chamber, and the verification report is filled in according to the results of each part. 6.3 A verification certificate is issued to the breakdown voltage tester that has passed the verification. A verification result notice is issued to the unqualified one. The cover style of the verification certificate and verification result notice is shown in the appendix of JB/T4279.1. 6.4 The factory-verified breakdown voltage tester is calibrated according to all items, and the periodic verification only needs to calibrate the items specified in Articles 5.2, 5.4, 5.5, 5.6 and 5.11 of this standard.
6.5 The verification cycle of the enameled wire breakdown voltage tester is generally set at 1 year, of which the verification cycle of the high temperature test chamber can be extended to 2 years. Additional notes:
This standard was proposed and managed by the Shanghai Cable Research Institute of the Ministry of Machinery Industry. This standard was drafted by the Shanghai Cable Research Institute of the Ministry of Machinery Industry and others. The main drafter of this standard is Zhu Bing.
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