This standard specifies the test equipment, sample preparation, test steps, test results and calculations for the tracking resistance test. This test method is used to test the ability of wires and cables to withstand damage caused by electrical traces caused by surface leakage under dirty conditions. The results obtained under dirty conditions not specified in this standard cannot be compared with the test results obtained under this test method. GB/T 3048.7-1994 Test methods for electrical properties of wires and cables Tracking resistance test GB/T3048.7-1994 Standard download decompression password: www.bzxz.net

National Standard of the People's Republic of China
Test methods for determining electrical properties of electric cables and wiresTracking resistance
GB/T3048.7—94
Replaces GB 3048.7---83
Test methods for determining electrical properties of electric cables and wiresTracking resistance test
Subject content and scope of application
This standard specifies the test equipment, sample preparation, test steps, test results and calculations for the "tree electric tracking test". This test method is used to test the ability of wires and cables to withstand damage caused by electric tracking due to surface leakage under pollution conditions. The results obtained under pollution conditions not specified in this standard cannot be compared with the test results obtained according to this test method. The general requirements, definitions and periodic calibration requirements for wire and cable electrical relay performance tests are specified in GB/T3048.1. 2 Reference standards
GB/T3048.1 General principles for electrical performance test methods for wires and cables 3 Test equipment
The wiring schematic diagram of the measurement system is shown in Figure 1.
Figure 1 Wiring schematic diagram of the measurement system
Specimen: 2--Protection resistor; 3--Test transformer; 4--Current measuring instrument 3. 1 Voltage test device
Test transformer: 50Hz, high voltage output not less than 4kV, when the output voltage is 4kV, the current is not less than 0.5A. Protection resistor: lkn. www.bzxz.net
Voltage and current measuring instruments: accuracy not less than 1.0 level. 3.2 Spray equipment
Has one or more nozzles. Spray range not less than above m. 3.3 Test liquid
Approved by the State Administration of Technical Supervision on May 19, 1994, implemented on January 1, 1995
CB/T 3048.7 94
Unless otherwise specified in the product standard, the recommended formula for the test wave body is about 0.2% sodium chloride (chemically pure) and 0.1% surfactant in 1 liter of water. The conductivity of the liquid is about 3000uS/cm (measured by a conductivity meter). The surfactant is recommended to be sec-octylphenyl polyoxyethylene ether, and other equivalent surfactants are also allowed. 4 Sample preparation
4.1 The length of the sample shall not be less than 150mm. The insulated core of the single-core cable shall be tested, and the single insulated core of the multi-core cable shall be tested. The appearance of the sample should be flat, without scratches, depressions or other defects on the surface. If there is dust, grease or other dirt, it can be wiped clean with silk cloth dipped in a solvent that does not corrode the sample. Then rinse with water several times. 4.2 Cut off the insulation on one end of the sample vertically about 20mm along the axis of the sample to expose the conductor. At 100mm away from the test insulation cut, wrap 2~3 turns of bare copper wire with a diameter of 1mm vertically around the axis of the sample. 4.3 The other end of the sample should be properly insulated to prevent discharge caused by the test liquid attached during the test. 5 Test steps
5.1 Place the prepared sample vertically and connect it according to Figure 1. The conductor is connected to the high-voltage end of the transformer, and the copper wire on the surface of the sample is grounded. 5.2 Adjust the spray device, the nozzle is at least 600mm above the ground and about 500mm away from the sample. The nozzle axis is at a 45° angle with the sample axis. The test liquid is sprayed directly on the sample. If multiple nozzles are used, the nozzles should be symmetrically or evenly distributed around the sample. The spray volume at the sample is about .5 ± 0.1 mm/min, and the spray pressure should be basically stable. 5.3 At the beginning of spraying, a 1kV power frequency test voltage is applied to the sample. The voltage should remain unchanged during the test. 6 Test results and calculations
6.1 Within the number of spray cycles specified in the product standard, if the sample does not have any of the following conditions, the test is considered qualified. a. Surface burning;
b. Continuous arc is formed between the high-voltage electrode and the grounding electrode; c. Surface leakage current exceeds the specified value;
d. The sample is broken down due to local corrosion of the insulation. 6.2 Spraying for 10 s and intermittent for 20 s is a spray cycle. Additional notes:
This standard was proposed by the Ministry of Machinery and Electronics Industry of the People's Republic of China. This standard is under the jurisdiction of the Shanghai Cable Research Institute of the Ministry of Machinery and Electronics Industry. This standard was drafted by the Shanghai Cable Research Institute of the Ministry of Machinery and Electronics Industry and others. The main drafters of this standard are Zhu Zhongzhu and Jin Biaoyi. This standard was first issued in 1983 and revised for the first time in May 1994.
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