This standard specifies the method for measuring the resistivity of metallic graphite products. This standard is applicable to the determination of resistivity of silver graphite brushes, copper graphite brushes and other metal graphite products. JB/T 6773-1993 Test method for resistivity of metallic graphite products JB/T6773-1993 Standard download and decompression password: www.bzxz.net

Machinery Industry Standard of the People's Republic of China
Resistivity Test Method for Metallic Graphite Products
This standard adopts IEC413-1972 "Test Procedure for Determining the Physical Properties of Brush Materials for Motors" with reference. 1 Subject content and scope of application
This standard specifies the method for measuring the resistivity of metallic graphite products. This standard is applicable to the determination of resistivity of silver graphite brushes, copper graphite brushes and other metal graphite products. 2 Reference standards
GB1994.1 Test methods for physical and chemical properties of electrical carbon products Specimen processing technology regulations 3 Principles
The basic principle of resistivity measurement is the double-arm bridge principle. 4 instruments or equipment
a.
b.
c.
d.
e.
f.||tt| |g.
h.
DC stabilized power supply voltage is 0~6V;
double-arm bridge, the accuracy is not less than 0.05 level, and matched with the corresponding galvanometer. Standard resistor, accuracy not less than 0.01 level, resistance value not more than 0.010, rheostat 8α, 6A
magnetoelectric ammeter, accuracy not less than level 1.0, range 0~10A, vernier caliper, accuracy 0.02mm# || tt | Show.
j.
5 specimens
JB/T 6773-93
The size of the specimen is 4mm×8mm×32mm or 3mm×4mm×21mm, the specimen The processing technology requirements and accuracy should comply with the regulations of GB1994.1.
6 test pieces
The test should be conducted under the conditions of an ambient temperature of 12 to 28°C, a relative humidity of no more than 80%, and no chemically corrosive gases. 7 Test steps
7.1 Measure the sample size, accurate to 0.01mm. 7.2 Select the standard resistor and proportional arm resistor. Approved by the Ministry of Machinery Industry on 1993-08-21
12
Implemented on 1993-10-01
5
JB/T 6773--93
10
Figure 1
1---potential needle, 2--sample, 3-
6-base*7--
shaft, 8-||tt ||Specimen fixture
10bZxz.net
40# copper mesh 14-sponge rubber 15~
Bakelite bottom plate, 9-
Current end, 10—|| tt||nut,
-measuring end.
7.3 Determine the spacing between the potential needles. When the sample is 4mm×8mm×32mm, the spacing between the potential needles is 16mm; when the sample is 3mm×4mm×21mm, the spacing between the potential needles is 10 mm. 7.4 Connect the electrical circuit as shown in Figure 2.
R3
kx
RA
G
R2
K
Figure 2 schematic diagram of the double-arm bridge| |tt||G—galvanometer A ammeter, R, R
R1
bridge proportional arm resistance
Rs, R4 bridge measuring arm resistance, R—- rheostat : Rx-u-sample resistance Rw-standard resistance, E-steady current power supply, K knife switch. 7.5 Select the measurement current, and select the minimum working current without causing the test sample to heat up and ensuring the measurement sensitivity. This current should not 13
exceed the current rating of the standard resistor.
JB/T 6773—93
7.6 The sample is placed between the two elastic electrodes in the length direction, so that the axis of the sample coincides with the center of the two electrodes. 7.7 Turn on the power, adjust the rheostat to make the current meet the requirements, and adjust the galvanometer to zero. 7.8 Place the potentiometer needle on the W×L surface, adjust the bridge knob, measure the resistance values ??on the two W×L surfaces, and take the arithmetic mean as the measured resistance value.
Result calculation
8
8.1
The resistivity is calculated according to the following formula
o
Where: p——resistivity, unm;
Rx sample resistance, mQ;
b—sample thickness, mm;
W—sample width, mm;
Lu potential needle spacing, mm.
8.2 The results obtained should be expressed to two decimal places. Additional notes:
Rx·b·W
Lu
This standard is proposed and managed by the Harbin Electrical Carbon Research Institute of the Ministry of Machinery Industry. This standard was drafted by Harbin Electric Carbon Guang and Harbin Electric Carbon Research Institute. The main drafters of this standard are Liu Shuqiu and Song Lijuan. 14
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