This standard specifies the verification items and technical requirements, verification instruments, verification methods, verification results and treatment of enameled wire electric heating forced ventilation test chambers. This standard applies to the verification of enameled wire electric heating forced ventilation test chambers. JB/T 4279.7-1994 Verification methods for enameled winding wire test instruments and equipment Electric heating forced ventilation test chambers JB/T4279.7-1994 Standard download decompression password: www.bzxz.net

Mechanical Industry Standard of the People's Republic of China
Verification Method of Enameled Winding Wire Test Instrument and Equipment Electric Heating Forced Ventilation Test Chamber
1 Subject Content and Scope of Application
JB/T4279.7-94
Replaces JB4279.786
This standard specifies the verification items and technical requirements, verification instruments, verification methods, verification results and processing of the enameled wire electric heating forced ventilation test chamber.
This standard is applicable to the verification of the enameled wire electric heating forced ventilation test chamber. 2 Reference Standards
JB/T4279.1 General Rules for Verification Method of Enameled Winding Wire Test Instrument and Equipment 3 Verification Items and Technical Requirements
The allowable temperature deviation of the working space of the forced ventilation test chamber is ±2.5℃. 4 Calibration instruments
4.i Thermocouple wire diameter is 0.5mm, and the node diameter is not more than 2.0mm. Nickel-chromium-copper-nickel (constantan), nickel-nickel-silicon or other material thermocouples.
4.2 The actual allowable measurement error of the DC digital voltmeter is ±0.05%. When the nickel-chromium-copper-nickel (constantan) thermocouple is used, the resolution of the digital voltmeter is not less than 10μV; when other thermocouples are used, the resolution of the digital voltmeter is not less than 1μV. 4.3 Thermocouple conversion switch.
4.4 Stopwatch, the division value is 0.1.s.
4.5 Ice bottle
5 Verification method
5.1 The working space is called the measured space during the verification process. The measured space is located near the center of the test box, and its interface is parallel to the interface of the space inside the box. The measured space cannot be smaller than the space occupied by the sample, and the center point of the space should not deviate from the temperature sensing end of the thermometer indicating the test temperature of the test box by 25mm.
5.2 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 box is not less than 300mm. Note: All thermocouples should be calibrated, and the 9 thermocouples should be composed of the same spool wire, so that the difference in potential between them when below 200℃ is converted into a temperature difference of no more than 0.2℃.
5.3 Adjust the temperature of the test box so that the temperature of the test box does not deviate from the test requirement temperature by ±2℃. 5.4 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 (0, 5, 10, 15, 20 minutes) to complete 5 measurements.
6 Calculate temperature deviation
6.1 Calculate spatial temperature deviation
Approved by the Ministry of Machinery Industry in 1994-1209
Implementation in 199506-01
JB/T4279.794bzxz.net
Calculate the average value of the thermoelectric potential of the 5 measured values ​​of the 9 measuring points respectively, and convert it to the average temperature of each measuring point by looking up the graduation table. Based on the average temperature of the center point of the measured space, calculate the spatial temperature deviation (accurate to 0.1℃) between the average temperature of each measuring point and the average temperature of the center point according to formula (1).
aim[t,-tol.
Wherein, the spatial temperature deviation of the ith vertex of the measured space, i1~8, is: ti-the average temperature of the ith vertex of the measured space, i=18, ℃; t. The average temperature of the center point of the measured space, C. 6.2 Calculation of time temperature fluctuation
According to formula (2), the difference between the highest temperature and the lowest temperature of the 8 vertices of the measured space in 5 measurements is calculated to obtain the time temperature fluctuation of the measured space (accurate to 0.1℃).
b; = bi mar - bi ai
Wherein: b, time temperature fluctuation of the ith vertex, i=1~8, C; b;—the highest temperature of the ith vertex, i=1~8, Cbm—the lowest temperature of the ith vertex, i=1~8, ℃. 6.3 Calculation of temperature deviation
The temperature deviation is the combination of spatial temperature deviation and time temperature fluctuation. The temperature deviation is calculated according to formula (3) with an accuracy of 0.1℃). At=±(a+
Wherein: △t-—the ith temperature deviation, i=1～8, a-the spatial temperature deviation of the ith point, i=1～8, ℃b,——the time temperature fluctuation of the ith point, i=1～8, ℃. 7 Calculation result processing
7.1 Check the calculation results of Article 6.3. If the maximum temperature deviation meets the requirements of Chapter 3 of this standard, the measured space is the working space. 7.2 Check the calculation results. If the temperature deviation of the measured space does not meet the requirements of Chapter 3 of this standard, the position of the measured space in the test chamber can be changed or the size of the measured space can be changed and then retested. In order to make The thermocouple at the center of the original measured space will not exceed 25mm from the temperature sensing end of the thermometer due to the change of the measured space. The position of this thermocouple can be moved. At this time, the thermocouple at this measuring point can no longer be located at the center of the measured space after the change.
7.3 This standard does not include the verification of the test chamber test temperature indicating instrument (or meter). For the test chamber where the test temperature is displayed by the temperature indicating instrument and the temperature sensing element of the instrument cannot be located at the center of the working space, the verification result should give the error between the value indicated by the temperature indicator at the verification temperature and the actual temperature at the center of the working space. 7.4 A verification certificate shall be issued to the qualified test chambers, and a verification result notice shall be issued to the unqualified ones. The cover of the verification certificate and verification result notice can be found in the appendix of JB/T4279.1. The certificate shall indicate the measurement temperature and the location and range of the working area. 7.5 The verification cycle of the electric heating forced ventilation test chamber is generally set at 2 years. 18
Inspection unit
Test chamber name and model
Test temperature
Depth, width and height of the test chamber (mm)
Depth, width and height of the working space (area) (mm) Working space (area) location (mm)||tt ||From the left box wall
From the right box wall
Test instrument model
1st measurement value mV
2nd measurement value mV
3rd measurement value mV
4th measurement value mV
5th measurement value mV
Average potential of measuring point mV
Average temperature of measuring point ℃
Spatial temperature deviation of measuring point ℃
Potential change of measuring point mV
Time temperature fluctuation of measuring point ℃
Temperature deviation of measuring point ℃
JB/T 4279.794
Appendix A
Test chamber temperature test record
(supplement)
Test date
Manufacturer
Specified temperature deviation
From upper chamber wall
From lower chamber wall
Test result: Maximum measuring point temperature deviation ℃ Factory number
Ventilation method
From rear chamber wall
From front chamber wall
Thermocouple model number
Note: The temperature deviation of the measuring point is ±[the measuring point Spatial temperature deviation ten (time temperature fluctuation of measuring point)
Cold end temperature
Note: Depth, width and height dimensions of test chamber (mm)
JB/T4279.7-94
Appendix B
Verification certificate template
(supplement)
Verification results
Distance of working space (area) from inner wall
Depth, width and height dimensions of working space (area) (mm) Additional notes:
This standard was proposed and managed by Shanghai Cable Research Institute of the Ministry of Machinery Industry. This standard was drafted by Shanghai Cable Research Institute of the Ministry of Machinery Industry and others. The main drafter of this standard is Zhu Bing.
Test results
Temperature deviation
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