This standard specifies the test equipment, test voltage and pre-test preparation for the DC spark test of insulated wire cores. This standard is applicable to the inspection of the insulation quality of the insulated wire cores of wires and cables, and can be used for intermediate inspection and factory testing of wires and cables. When implementing wire and cable product standards, the DC spark test can be used instead of the power frequency spark test. GB/T 3048.15-1992 DC spark test method for insulated wire cores of wires and cables GB/T3048.15-1992 Standard download decompression password: www.bzxz.net

National Standard of the People's Republic of China
D. C, spark test method for insulated cores of wires and cables
D. C, spark test method for insulated cores Subject content and scope of application
GB/T 3048:15-92
This standard specifies the test equipment, test voltage and preparation before the test for the DC spark test of insulated cores. This standard is applicable to the inspection of the insulation quality of the insulation layer of the insulation core of wires and cables, and can be used for the intermediate inspection and factory test of wires and cables. When implementing the standard promotion of wire and cable products, the DC spark test can be used to replace the power frequency spark test. 2 Test equipment
The DC spark test machine is shown in Figure 1. The machine includes a DC high-voltage power supply, test electrodes, a voltmeter, a breakdown indicator and necessary electrical facilities and connecting wires. The main components and the entire device should meet the following requirements. 2
1---Tested product; 2-Test electrode box; 3-Reel: 4:--DC high voltage generator; 5-Detection and control device
2.1 DC high voltage power supply
The positive pole of the power supply should be grounded, and the negative pole should be connected to the test electrode by a low-capacitance unshielded wire. The output voltage of the power supply should be a DC voltage with a ripple factor of no more than 5%.
The potential difference between the test electrode and the ground should be displayed by the test voltmeter of the spark machine. The test voltmeter can be directly connected to the output terminal of the spark machine or connected by other suitable methods, but its indication error should be within the range of 5%. 2.2 Test electrode
2.2.1 The length of the electrode should ensure that each point of the tested insulated wire core is under the electrode for no less than 0.0015 seconds. The width of the electrode should be greater than the maximum outer diameter of the tested insulated wire core by 30mm, and the bottom can be made into a V\ shape or a \U\ shape. Approved by the State Administration of Technical Supervision on February 19, 1992, and implemented on October 1, 1992.
GB/T3048.15-92
Note: The maximum speed of the insulated wire core passing through the electrode per meter is 60m/mi. "2.2.2 The electrode is a contact electrode made of metal. A ball chain or a ring chain can be used. The chain length should be greater than the depth of the bottom electrode of the "V" or "U" shape. The distance between two adjacent chains should not be greater than 8mm.
Electrodes that are in direct contact with the insulated wire core under test are not allowed to use mercury or any other liquid materials. Note: The distance between two adjacent chains should not be greater than 8 mm. It refers to the distance between two adjacent chains in any direction. 2.2.2. 1 The diameter of the beads is 2~5 mm. The distance between two adjacent beads on a string of ball chains should not exceed 2.5mm. 2. 2.2.2 The ring is composed of a metal wire with a diameter greater than 0.8 mm. The outer diameter of the ring should not be greater than 5 mm. If other shapes such as ellipse are used, the narrow side should not be larger than 5 mm. There should be no less than 20 rings on every 100 mm long chain. 2.2.2.3 The beads or rings on the chain should be evenly distributed, with a smooth surface, and should not have any burrs that may scratch the insulated wire core under test, and each section of the beads or rings should be flexible. The bead chain or ring chain should be arranged alternately. 2.3 Breakdown indicator
The breakdown indicator consists of a digital display counter and an alarm, which can record and alarm for each breakdown. The breakdown indicator should be able to maintain its indication until the next non-breakdown is recorded or the indicator is manually reset. The alarm time of the alarm alarm should be able to last for several seconds. 2.4 Guarding electrode
There should be guarding electrodes at both ends of the test electrode. The length of the guarding electrode should not be less than 15mtm, and all bead chains and ring chains should be consistent with the test electrode. The distance between the guarding electrode and the test electrode The distance should ensure that no flashover occurs on the surface of the sample insulation at the highest test voltage. 2.5 Sensitivity
The sensitivity is tested with an artificial breakdown device. bZxz.net
The spark gap in the artificial breakdown device should consist of a metal plate and a metal needle tip that rotate relative to each other. The metal plate and the metal needle tip have a distance of 0.25±0.05mm per second, and the duration is 0.0059. The needle tip is negative and the metal plate is positive.
2.5.1 Minimum sensitivity test
Under no-load conditions, adjust the test electrode voltage to 5kV DC. When the artificial breakdown device is connected, the steady-state current of the spark gap in the short-circuit state should not exceed 600 μA. In order to limit the steady-state current to an appropriate range of values, an additional resistor can be connected in series. When testing the minimum sensitivity, the artificial breakdown device that meets the above requirements should be connected first, the test electrode voltage should be adjusted to DC 5kV, and the artificial breakdown device should be started, so that the spark between the metal plate and the needle tip is broken down 20 times continuously. The breakdown counter of the spark tester is required to record 20 times, and each breakdown should be counted accurately, without over-counting or missing. 2.5.2 Stability test
After the minimum sensitivity meets the requirements, the additional resistor (if any) should be short-circuited, and the test electrode voltage should be adjusted to the highest test voltage of the equipment, and the artificial breakdown device should be started, so that the spark between the metal plate and the needle tip is broken down 20 times continuously. The breakdown counter of the spark tester is required to record 20 times. Each breakdown should be counted accurately, without over-counting or missing. 2.6 Safety interlock device
When the test electrode box of the test machine is started, the safety interlock device should ensure that the commercial voltage power supply is automatically cut off and the test electrode is automatically grounded. 3 Test voltage
The test voltage is as specified in Table 1.
4 Before the test, each
Nominal thickness of insulation
0.25<80.5
0.5<8≤1. 0
1.0≤1.5
GB/T3048.15-92
4.1 The DC spark test machine and the wire-receiving and wire-releasing devices should be reliably grounded 4.2 Before each test, the safety interlock device should be checked and must operate normally. 4.3 The conductor of the test object should be reliably and continuously grounded 5 Test results and evaluation
The number of breakdowns per unit length (such as per kilometer) of the test object is the test result. Additional instructions:
This standard is proposed by the Ministry of Machinery and Electronics Industry of the People's Republic of China. This standard is under the jurisdiction of Shanghai Cable Research Institute of the Ministry of Machinery and Electronics Industry. This standard was drafted by Shanghai Cable Research Institute of the Ministry of Machinery and Electronics Industry. The main drafters of this standard are Guo Chenghong and Huang Yiming. This standard is equivalent to BS5099-1974 and AMD3110, 4025. Test voltage
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