This standard specifies the test method for continuous detection of the resistance of bare conductors with uniform cross-sectional area. This standard is applicable to the continuous test of the resistance of round wires and flat wires such as electric heating, resistance heating, resistance alloys, etc. JB/T 7129-1993 Continuous test method of resistance of JB/T7129-1993 standard download decompression password: www.bzxz.net

Mechanical Industry Standard of the People's Republic of China
JB/T7129-1993
Meter resistance continuous test method
1993-10-08 Issued
Ministry of Machinery Industry of the People's Republic of China
1994-01-01 Implementation
Meter resistance continuous test method
Subject content and scope of application
This standard specifies the test method for continuous detection of meter resistance of bare conductors with uniform cross-sectional area. This standard is applicable to continuous test of meter resistance value of round wire and flat wire materials such as electric heating, resistance, heating resistance alloy. Reference Standard
GB6146 Test Method for Resistivity of Precision Resistance Alloy 3 Terminology
3.1 Meter resistance
resistancepermeter
Resistance value per meter length of bare conductors with uniform cross-sectional area of ​​round wire and flat wire. Note: Standard resistance - the resistance of the sample per meter at room temperature of 20℃, calculated as follows. Rm2o=pro/Aro
In the formula, Rmm-the resistance value of the sample per meter at 20℃ a/mP2e-the resistivity of the sample at 20℃ pn·mA20-the cross-sectional area of ​​the sample at 20℃ mmwwW.bzxz.Net
continousmeasurment
3.2 Continuous measurement
JB/T7129-1993
The sample is constantly moving: the resistance value of any unit length (meter) can be correctly measured by a certain measuring device. Measurement principle
The continuous measurement of meter resistance is based on the principle of current-voltage method. It is known from the formula Rx=V/1 that when there is an accurate and stable direct current, a voltage proportional to the resistance is generated when passing through the measured resistance. As long as the accuracy of the voltage and current test is guaranteed, the accurate value of the measured resistance Rx can be obtained.
5 Measuring device
Figure 1 is a measurement schematic diagram
Approved by the Ministry of Machinery Industry on October 8, 1993
Hao District
District District
Measurement schematic diagram
Implemented on January 1, 1994
5.1 Resistance measuring instrument
JB/T7129-1993
Use a micro-ohmmeter of not less than 0.1 level, and the measuring range is 1×10-5～2×10°a. Other instruments of the same level can also be used. 5.2 Length measurement uses a standard ruler, and the graduation value should be not less than 0.5mm. 5.3 The measurement adopts the four-terminal measurement method. For wires and wires with a diameter of more than 0.2mm, the measuring terminal is a rolling or knife-edge type with an electromagnet mechanism. The contact pressure between the measuring terminal and the material being measured is 5～25N. The measuring terminal for thin wires with a wire diameter less than 0.2mm adopts a pulley type.
5.4 The sampling rate is 0.5~1cm and 15~30cm each time. The measuring speed is 10~25m/min.
6 Sample
6.1 The sample is a wire or flat wire bare wire tube product such as electric heating, resistance, heating resistance alloy, etc. 6.2 Measuring material specifications:
Wire: Q0.07~1.0mm
Flat wire: width ≤5mm
Thickness ≤0.5mm
6.3 The sample should have no obvious oxidation, no welding points and cracks, and the surface should be straight, smooth and oil-free. 7 Test environment
The temperature of the test room is 20±5℃, and the relative humidity is not more than 80%. 7.2 There should be no interference from strong vibration and strong magnetic field during measurement. 8 Measurement procedure
Use a standard ruler to measure the length of the two potential ends to be 1000mm, and the measurement error is ±0.1%. 8.1
Put the sample to be tested on the pay-off rack and adjust the damping screw. 8.23
Select the working mode, sampling frequency and running speed. 8.3
8.4 After turning on the machine, calibrate and adjust according to the instruction manual of the micro-ohmmeter. 8.5 Set the standard resistance value (R) and the specified tolerance (%) of the sample to be tested. 8.6 After the test is run according to the procedure, when the measured value is out of tolerance, that is, Rx>R (1+%%) or Rx
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