This standard specifies the resistivity measurement method for wire used in rivet contacts. This standard is applicable to various wires used in rivet contacts processed by various methods, and also to other wires used in contacts. JB/T 7780.3-1995 Mechanical and physical properties test of wire used in rivet contacts JB/T7780.3-1995 Standard download decompression password: www.bzxz.net

Mechanical Industry Standard of the People's Republic of China
Test methods for mechanical and physical properties of wires for rivet contacts Resistivity measurement methods for wires for rivet contacts 1 Subject content and scope of application
This standard specifies the resistivity measurement method for wires for rivet contacts. JB/T 7780.3—1995
This standard applies to various types of wires for rivet contacts processed by various methods. It is also applicable to other wires for contacts. 2 Principle
The basic principle of resistivity measurement is the DC double-arm bridge principle. 3 Measuring instrument
3.1 The measuring instrument consists of a DC double-arm bridge with an accuracy of 0.2 or above and its accessories. 3.2 The length is measured using a vernier caliper or ruler, and its graduation value should not be greater than 0.5mm. 3.3 The wire diameter is measured using a dry ruler with an accuracy of 0.01mm. 3.4 The special test fixture for measuring the resistivity of wires is shown in the figure below. 2
1—BasewwW.bzxz.Net
Schematic diagram of resistivity measurement fixture
2-Screw,
4-Potential terminal,
5-Current terminal,
3-Specimen,
6-Compression screw
The measuring length between the two potential terminals is at least 300mm, and the distance between the potential terminal and its adjacent current terminal is 50~~100mm. 3.5 The resistance value of the connecting wire between the reference standard resistor and the specimen should be significantly smaller than the resistance value of the reference standard resistor and the specimen. 4 Specimen
4.1 The surface of the wire should be free of cracks or other defects, and should be smooth, free of oil stains and oxide layers. 4.2 The wire diameter change should not exceed 1%.
Approved by the Ministry of Machinery Industry in 1995-1009
Implemented in 1996-01-01
5 Measurement
JB/T 7780.3-1995
5.1 The diameter of the wire is measured by a dry ruler. The two ends and the middle of the sample are measured once in two mutually perpendicular directions. The arithmetic mean is taken, and then the average value of the cross-sectional diameter measured at three locations is taken. 5.2 During arbitration measurement, the cross-sectional area of ​​the sample is determined by the mass, density and length of the sample. Density measurement is carried out in accordance with JB/T7780.1--1995.
5.3 When using a special fixture to measure the length of the sample, use a vernier caliper to repeatedly calibrate the distance between the two parallel potential ends on the fixture. When measuring the length with a ruler, the measurement error should be less than 0.2%. 5.4 After the sample is fixed in the fixture, it is necessary to carefully check whether the measurement circuit is accurate and adjust the zero position of the galvanometer before measurement. 5.5 The ambient temperature during measurement is 20 ± 10 °C. 6 Results and calculations
The volume resistivity is calculated by formula (1):
Where: p is the volume resistivity of the sample, uQ·cm, R is the resistance value of the sample, un;
d is the wire diameter, cm,
L is the measured length between the two potential ends of the sample, cm. The calculation result is rounded to three significant figures.
Additional notes:
This standard is proposed and managed by the Guilin Electrical Science Research Institute of the Ministry of Machinery Industry. This standard was drafted by the Guilin Electrical Science Research Institute. The main drafter of this standard is Jiang Hansong
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