This standard specifies the test equipment, test voltage, pre-test preparation, test evaluation and calibration of spark test machine for power frequency spark test of insulated wire core. This standard is applicable to the inspection of the insulation quality of rubber and plastic wire and cable insulated wire core, and can be used for intermediate inspection and factory test of wire and cable. The relative humidity of the test environment should be kept below 85%. This test method is not applicable to the inspection of insulated products with conductive wire cores made of any non-high conductive material. GB/T 3048.9-1994 Test method for electrical properties of wires and cables Power frequency spark test of insulated wire core GB/T3048.9-1994 Standard download decompression password: www.bzxz.net

National Standard of the People's Republic of China
Test methods for electrical properties of electric cables and cables
Power frequency spark test of insulated cores
GB/T 3048.9--94
Replaces GB 3118.9 83
Test methods for determining electrical properties of electric cables and wiresA, C. spark test of insulated cores1Subject content and scope of application
This standard specifies the test equipment, test voltage, test preparation, test evaluation and verification of spark test machine for power frequency spark test of insulated cores.
This standard is applicable to the inspection of the insulation layer quality of rubber and plastic wire and cable insulated cores, and can be used for the test of wire and cable in the central inspection factory.
The relative humidity of the test environment should be kept below 85%. This test method is not applicable to the inspection of insulated products of conductive cores made of any non-commercial conductive materials. The general requirements, definitions and periodic calibration requirements for the electrical performance test of wires and cables are specified in GB/T3U48.1. 2 Reference standards
GB/T3048.1 General principles for electrical performance test methods for wires and cables JB4728.10 Verification methods for rubber and plastic wire and cable test instruments and equipment Spark test machine 3 Test equipment
The schematic diagram of the spark test machine is shown in Figure 1. The main components and individual devices should meet the following requirements; 3.1 High voltage power supply
The power supply frequency is 40~~60Hz, and the voltage waveform should be approximately sinusoidal. The potential difference between the high voltage electrode and the ground should be displayed by the test voltage indicator of the spark machine. The meter can be directly connected to the high voltage power supply output spectrum or connected by any other suitable connection method, but the indication error should be within the standard of +5. The test voltage indicator is calibrated according to JB4728.10. Approved by the State Administration of Technical Supervision on May 19, 1994, 199501-01 for implementation
GB/T 3048. 9-94
Figure 1 Schematic diagram of spark tester
1 Sample conductor, 2-Test wire: 3-Isolation electrode: 1-Electrode box::-Test transformer; B-·Voltage regulator; 7 Voltage circuit breaker 8-Power supply? 9-Insulation defect indicator (can also be installed in the power supply system): 10-·-Transformer grounding: 11 Protective electrode? 12 Insulator + 13 Take-up reel; 14-Grounding 3.2 Test electrode
3.2.1 The effective length of the electrode should make the insulation of the test object pass through the electrode for no less than 0.05 at each point. The effective width should be greater than the maximum diameter of the test wire by 30mm. The bottom can be made into a *V” shape or a \U\ shape. Maintain good insulation to the ground, so that at the highest test voltage, when the insulator is wet, the light flower machine should also operate normally. The electrode box shell is grounded. 3.2.2 The electrode is a contact electrode made of metal, which can be made of a ring chain or a ring chain. The chain length should be greater than the depth of the bottom electrode of the \V” or “UI\ shape. The distance between two adjacent chains should not be less than 8mm.
3.2.2.1 The diameter of the beads is 2~~~5mm, and the distance between two adjacent beads on the bead chain should not exceed 2 .5m1m3.2.2.2 The ring is made of metal wire with a diameter greater than 0.8mm. The outer diameter of the ring should not exceed 5mm. If it is a round or other shape, the narrow side should not exceed 5mm. There should be no less than 20 rings on each 100mm long ring chain. 3.2.2.3 The beads or rings on the chain should be evenly distributed, with a smooth surface and no burrs that can scratch the insulation of the test object. Each section or ring should be flexible.
3.3 Guarding electrode
Both ends of the test electrode should have a grounding guard. The width of the protective electrode should be no less than 15nI, and the bead chain or ring chain used should be consistent with the test electrode. The distance between the protective electrode and the test electrode should ensure that no flashover occurs on the insulation surface of the test specimen under the normal maximum test voltage. 3.4 Safety protection interlocking device
Ensure that the high voltage power supply is automatically disconnected when the test electrode is opened. 3.5 Tooth penetration indicator
3.5.1 The function should be able to ensure the correct recording of the number of breakdowns, trigger the circuit breaker to disconnect the high voltage power supply and the drive system power supply. It can be cut off when necessary.
3.5.2 The breakdown current sampling can be connected in series to the upper end of the resistor on the low-voltage side of the secondary winding of the test transformer for sampling, and other practically equivalent connection methods are also allowed to be used for sampling.
3.5.3 The minimum sensitivity is tested using an artificial breakdown device. The artificial breakdown device consists of a metal needle and a metal plate. The plate rotates relative to the needle tip. For each rotation, the needle tip passes over the plate once, and the duration of each time is 0.025. When the needle tip passes over the plate, the distance between the two is 0. 25 on 0. 05 mm.
When testing the minimum sensitivity, adjust the no-load voltage of the test transformer to 3kV. The short-circuit steady-state current at this voltage should be limited to less than 600 μA. If necessary, a series impedance can be connected. GB/T3048.9-94
Turn the above artificial breakdown device for 20 consecutive times, with a time interval of 18 each time. The artificial spark gap should be continuously punctured, and the breakdown indicator should accurately record the number of each breakdown. 3.5.4 Stability After completing the test in Article 3.5.3, short-circuit the additional impedance (if it is external). Put a section of test wire without defects between the electrodes, or connect a capacitor with the same capacitance value as the test wire between the plate electrode and the needle electrode of the artificial breakdown device, raise the electrode voltage to the highest voltage required for testing, rotate the above artificial breakdown device for 20 consecutive times, and the time for each rotation is 1s. The artificial spark gap should be punctured, and the breakdown indicator should accurately record the number of each breakdown. Note: ① When conducting the tests 3.5.3 and 3.5.4, the trigger signal should be disconnected to ensure that the power supply of the test transformer is not disconnected. ② When conducting the test 3.5.3, the needle should be replaced for each test. The angle of the needle should not be greater than 60° and the diameter should not be greater than 2mm. ③ When conducting the test 3.5.4, a thicker copper needle can be used to prevent the needle from melting. ③ When conducting the combined test 3.5.4, the section of the tested wire used should be the wire with the maximum capacitance value to be tested by the spark machine. 4 Test voltage
The test voltage is as specified in Table 1.
Nominal insulation thickness, mm
0. 25-.840. 5
0. 581. 0
1. 0<≤1.5
Test voltage (effective value), kV
Note: For non-sealed insulation structures, such as wrapped structures without bonding layers, the test voltage should be specified in the product standard. 5 Preparation before the test
5.1 The spark test equipment and the wire-retracting and releasing device should be reliably grounded. 5.2 Before each test, the electrode safety protection interlock device should be checked and must operate normally. 5.3 The conductor of the test object should be reliably and continuously grounded. 5.4 Before the test object enters the electrode, appropriate methods should be used to remove moisture from the insulation surface to prevent flashover during the test. 6 Test results and evaluation
The number of breakdowns per unit length (such as per meter) of the test object is the test result. 7 Calibration of spark tester
Spark tester should be calibrated at least once a year, and after overhaul or adjustment. Calibration method shall be in accordance with JB 4278.10.
Additional Notes
GB/T 3048.9-94bZxz.net
This standard was proposed by the Ministry of Machinery and Electronics Industry of the People's Republic of China. This standard was drafted by the Shanghai Cable Research Institute of the Ministry of Machinery and Electronics Industry. The main drafters of this standard are Zhang Huan and Guo Chenghong. This standard was first issued in 1983 and first subscribed in May 194
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