GB/T 2951.4-1997 General test methods for cable insulation and sheath materials Part 1: General test methods Section 4: Low temperature tests
Some standard content:
1 Scope
National Standard of the People's Republic of China
Common test methods for insulatingand sheathing materials of electric cablesPart 1, Methodg for general applicatlonSection four; Test at low temperatureGB/T 2951. 4—1997
idt IEC 811-1-4:1985
No.1(1993)1st Amendment
Replaces GB/T2951.1
GB/2951.12~2951.14-94
GB/T2951 standard specifies the test methods for composite insulation and sheath materials of power distribution cables and communication cables, including marine cables.
GB/T2951.4 specifies the wide and low temperature test methods, which are applicable to the ethylene chloride and ethylene insulation and sheath materials of wires and cables. 2 Test requirements
This standard does not specify all test conditions (such as temperature, duration, etc.) and all test requirements, which should be specified in the relevant cable product standards.
Any test requirements specified in this standard can be modified in the relevant cable product standards to meet the needs of special types of cables. 3 Scope of application
The test conditions and test parameters specified in this standard are applicable to the most commonly used types of insulation and sheath materials for cables, wires and cords. 4 Type tests and other tests
The test methods described in this standard are primarily used as type tests. For some test items, the conditions for type tests and frequently performed tests (such as routine tests) are essentially different, and this standard has specified these differences. 5 Pretreatment
All tests should be carried out after the insulation and sheath materials are extruded or vulcanized (or cross-linked) for at least 16 hours. 6 Test temperature
The test should be carried out at the temperature specified in the relevant cable product standards. 7 Intermediate value
The test data with a certain number should be arranged in ascending or descending order. If the number of valid data is an odd number, the intermediate value is the middle value. If it is an even number, the intermediate value is the average of the two middle values. Approved by the State Administration of Technical Supervision on October 28, 1997 and implemented on October 1, 1998
8 Low temperature test
8.1 Low temperature winding test for insulation
8.1.1 Overview
GB/T 2951. 4—1997
This test is generally applicable to round insulated cores with an outer diameter of 12.5 mm or less and fan-shaped insulated cores for which dumbbell specimens cannot be prepared. If specified in the relevant cable product standards, the test should be carried out on large-size insulated cores. Otherwise, the large-size insulated cores should be subjected to the low-temperature tensile test described in Article 8.3.
8.1.2 Sampling and specimen preparation
Take two specimens of appropriate length from each insulated core to be tested. If there is an outer sheath, it should be removed before being used as a specimen. 8.1.3 Test instrument
The test equipment recommended for this test is shown in Figure 1 and the notes. It basically consists of a rotating axis and a specimen guide device. Another single-axis device that is actually equivalent to the device in Figure 1 can also be used. This test equipment should be placed in a low-temperature box before and during the test. 8. 1.4 Test procedure
The specimens shall be fixed to the equipment as shown in Figure 1. The equipment with the specimens installed shall be placed in a low temperature box at the specified temperature for not less than 16 hours. The 16-hour cooling time includes the time required to cool the equipment.
If the test equipment has been precooled, the cooling time may be shortened, but not less than 4 hours, as long as the specimens have reached the specified test temperature. If the test equipment and the test are precooled, it is sufficient to cool each specimen after fixing it to the test equipment for 1 hour. After the specified cooling time, perform the cooling according to 8.1 .5 Rotate the test rod under the conditions specified in Article 1.5 so that the sample is neatly wound into a tight spiral on the test rod. If it is a brush-shaped specimen, the round "back" of the specimen should be in contact with the test. Then, keep the specimen on the test rod and restore it to a temperature close to the ambient temperature. 8.1.5 Test conditions
The test temperature shall be in accordance with the relevant cable product standards. The diameter of the test rod shall be 4 to 5 times the diameter of the specimen (see the table below). The test rod shall be rotated at a rate of about 59 revolutions per turn, and the number of turns shall be as specified in the table below Test outer diameter.mm
2. 5ds54.5
6. 5-ds.8. 5
Rotation effect
per:-The actual diameter of the specimen shall be measured with a vernier caliper or measuring tape. For sector-shaped specimens, the minor axis shall be used as the equivalent point diameter to determine the test diameter and the number of turns.
For flat flexible wires, the minor axis size of the test rod shall be used to determine the diameter and number of turns of the test rod. During winding, the short side is perpendicular to the test rod. 8.1.6 Evaluation of test results
After the test is completed as specified in 8.1.4, check the specimens still on the test rod. When inspected with normal or corrected vision without a magnifying glass, both insulation test pieces should be free of any cracks. 8.2 Low-temperature winding test of sheath
8.2.1 Overview
This test is generally applicable to cables with an outer diameter of 12.5 mm or less and flat cables with a short axis size of 29 mm or less. If specified in the relevant cable product standards, the test can be carried out on human-sized cables. Otherwise, the sheath of large-sized cables should be subjected to the low-temperature tensile test described in 8.4.
8.2.2 Sampling and specimen preparation
CB/T 2951. 4 -- 1997
Take two cable specimens of appropriate length from each sheath F to be tested. Before testing, remove all the sheath coverings. 8.2.3 The test equipment, procedures and test conditions shall be in accordance with the provisions of 8.1.3, 8.1.4 and 8.1.5. For cables with armored or concentrically stranded conductors in the outer sheath, the diameter of the test rod shall be in accordance with the provisions of the relevant cable product standards. 8.2.4 Evaluation of test results
After the test in accordance with 8.1.4 is completed, the specimens still on the test rod shall be inspected. When inspected with normal vision or corrected vision without a magnifying glass, the sheaths of both specimens shall be free of any cracks. 8.3 Low-temperature tensile test of insulation
8.3.1 Overview
This test is applicable to the insulation of insulated wire cores that are not subjected to the low-temperature winding test specified in 8.1.1. 8.3.2 Sampling
Two specimens of appropriate length shall be taken from each tested wire core. 8.3.3 Preparation of test specimens
After all sheaths (including the outer semi-conductive layer, if any) are stripped off, cut the insulation along the axial direction; then remove the conductor and the inner conductive layer (if any).
The insulation test strip shall be ground or flattened to obtain a smooth and parallel surface between the two marking lines described below. Be careful to avoid overheating during grinding. For examples of cutting machines, see Appendix A of GB/T2951.1-1997. Polyethylene (PE) and polypropylene (PP) insulation can only be flattened, not ground. The thickness of the insulation test strip after grinding or flattening shall not be less than 0.8mm; not more than 2.0mm. If a test strip with a thickness of 0.8um cannot be obtained from the original sample, the minimum thickness allowed is 0.6mm. All test strips shall be treated at ambient temperature for at least 16h, and then two dumbbell test pieces as shown in Figure 3 or Figure 4 (if necessary) can be punched out along the axis of each test strip. If possible, two dumbbell test pieces should be punched out side by side.
For fan-shaped wire cores, dumbbell test pieces should be cut on the "back" of the insulated wire core. If the distance between the marking lines can be directly measured during the test, the marking lines should be marked on the dumbbell test piece according to the last paragraph of 9.1.3a) of GB/T2951.1-1997. 8.3.4 Test equipment
The test can be carried out on an ordinary tensile machine with a low temperature device, or on a tensile machine placed in a low temperature box. If a liquid refrigerant is used, the pretreatment time at the specified test temperature should not be less than 10 minutes. When the test equipment and the sample are cooled in the air together, the cooling time should be at least 4 hours. If the test equipment has been refrigerated, the cooling time can be shortened by 2 hours. If the test equipment and the sample have been precooled, the cooling time for fixing the sample on the test equipment should be not less than 30 minutes. If a mixed liquid is used for cooling, the liquid should not damage the insulation and sheath materials. For tensile testing, it is best to use a test device that can directly measure the distance between the marking lines, but a test device that measures the displacement between the grips can also be used.
Note: A suitable refrigerant is a mixture of ethanol or methanol and dry ice. 8.3.5 Test steps and test conditions
The chuck of the tensile machine should be non-self-tightening. The length of the dumbbell specimen clamped in the two pre-lifted chucks is the same. If the distance between the marking lines is directly measured during the test, the free length between the chucks should be about 30mm for both dumbbell specimens.
If the displacement between the chucks is measured, the free length between the chucks for the dumbbell specimen in Figure 3 should be (30±0.5)mm; for the dumbbell specimen in Figure 4, the free length between the chucks should be (22±0.5)mm. GB/T2951.4—1997
The separation speed of the chuck of the tensile machine should be (25±5)mm/min. The test temperature shall be in accordance with the provisions of the relevant cable product standards for this type of insulation material. The elongation is determined by the distance between the marking lines when pulling off, or the distance between the chucks when pulling off. 8.3.6 Evaluation of test results
Calculate the elongation by the ratio of the increase in the distance between the marking lines to the original distance of 20 mm (10 um in the case of dumbbell test pieces in Figure 4), expressed as a percentage.
If the method of measuring the distance between the clamps is used, the original distance should be 30 mm for the dumbbell test piece in Figure 3 and 22 mm for the dumbbell test piece in Figure 4. When this method is used, the test piece should be measured before it is removed from the test equipment. If the test piece partially slips out of the clamp, the test data will be invalid. There should be at least three valid data for calculating the elongation, otherwise the test should be repeated. Unless otherwise specified, the valid test results shall not be less than 20%. In case of dispute, the method of measuring the distance between the marking lines should be used. 8.4 Low-temperature tensile test of sheath
8.4.1 Overview
This test is applicable to cable sheaths that are not subjected to the low-temperature winding test specified in Article 8.2.1. 8.4.2 Sampling
Two specimens of appropriate length shall be taken from each sheath to be tested. 8.4.3 Preparation of specimens
After all sheaths are removed, the sheath shall be cut open along the axial direction and the insulating core, filler and other structural elements on the surface (if any) shall be removed.
If the inner and outer surfaces of the sheath are smooth and the average thickness does not exceed 2.0 mm, the specimen does not need to be flattened or ground. Specimens with a thickness exceeding 2.0 mm or specimens with brown mark indentations and indentations or ridges on the inner side shall be flattened or ground to obtain two smooth parallel surfaces with a thickness of not more than 2.0 mm and not less than 0.8 mm. If a 0.8 mm specimen cannot be obtained from the original specimen, the minimum thickness allowed is 0.6 mm. Care should be taken to avoid overheating and excessive mechanical damage during flattening or flattening. For an example of a cutting machine, see Appendix A of GB/T2951.1-1997. All specimens shall be stored at ambient temperature for at least 16 h. Afterwards, two dumbbell specimens as shown in Figure 3 or Figure 4 (if necessary) shall be punched out along the axial direction of each specimen. If possible, two dumbbell specimens shall be punched out side by side. If the distance between the marking lines is directly measured during the test, the marking lines shall be made on the dumbbell specimens in accordance with the last paragraph of Section 9, 1.3a) of GB/T2951.1-1997. 8.4.4 Test equipment In accordance with the provisions of Article 8.3.4. 8.4.5 Test procedures and test conditions In accordance with the provisions of Article 8.3.5, 8.4.6 Evaluation of test results In accordance with the provisions of Article 8.3.6.
8.5 Low temperature impact test on polyvinyl chloride insulation and sheath 8.5.1 Overview
This test is applicable to all types of polyvinyl chloride sheathed cables, regardless of the insulation type of the insulated core. If specified in the relevant cable product standards, it is also applicable to the polyvinyl chloride insulation of unsheathed wires, cords and fan-flat cords. The polyvinyl chloride insulation of sheathed cables is not directly subjected to low temperature impact test. 8.5.2 Sampling and specimen preparation
Take three finished cable specimens, each with a length of at least 5 times the cable diameter and a minimum of 150 mm. All outer sheaths should be removed. 8.5.3 Test equipment
GB/T 2951.4—1997
The equipment used for this test is shown in Figure 2, with annotations attached. The equipment should be placed on a sponge rubber pad about 40 mm thick and should be placed in a low temperature box before and during the test. 8.5.4 Test conditions
The test temperature should be specified by the relevant cable product standards. For fixed cable samples, the test weight shall be as specified in the following table: External diameter, nm
Less than or equal to
For samples of flexible cables, cords and communication cables, the test weight shall be as specified in the following table: External diameter, nm
For fan-shaped cords
Less than or equal to
The external diameters listed in the table shall be measured with a vernier caliper or measuring tape for each sample. When testing fan-shaped cords, the short axis shall be perpendicular to the steel base. 8.5.5 Test steps
Drop weight
The test equipment and the cable samples to be tested shall be placed side by side in a low temperature box and kept at the specified temperature for at least 16 hours, including the cooling time of the test equipment. If the test equipment has been pre-cooled and the sample has reached the specified test temperature, the cooling time may be shortened, but shall not be less than 1 hour.
After the specified cooling time, each sample shall be placed in the position shown in Figure 2 in turn, and the drop weight shall be dropped from a height of 100 mm. After the test, allow the specimen to return to near room temperature. Then check the insulation of the unsheathed cable or cord. Keep the specimen straight and twist it 360° every 100 mm. Then check the insulation. If the insulation cannot be twisted in this way, check it according to the provisions for the sheath. Before checking the sheath of the cable or cord, allow it to return to near room temperature and then immerse it in hot water. Then cut the sheath along the cable axis.
Check the inner and outer surfaces of the sheath and insulation. Only the outer surface of the insulation of the sheathed cable or cord is checked. 8.5.6 Evaluation of test results
When checked with normal vision or corrected vision without a magnifying glass, none of the three specimens should have cracks. If one of the three specimens has a crack, take three more specimens and repeat the test. If all three specimens have cracks, the test requirements are met. If any of the specimens still have cracks, the cable or sheath does not meet the test requirements. Balance block
1 sS-1.5 d3
2d -1.21, 5d
GB/T2951.4—1997
x about 30mm
Front view
View A
Regulation drawing (sample circumference)
3 In horizontal position (HP), the sample should not be pressed down too much. 4 In inclined position (S, P.), the sample should not be pointed up too much. Figure 1 Low temperature winding equipment
Shi Shige
GB/T 2951. 4 -- 1997
Yicheng sample
Steel base 1okg
Middle iron block 100g
Xuan inverted space
A cut surface
Figure 2 Impact test equipment
Marking line
Figure 3 Bell test piece
Dimension unit: mm
Dimension unit: mn
GB/T 2951. 4 -- 1997
Marking line
Small dumbbell test piece
Dimension unit: nm2 Sampling
Two specimens of appropriate length shall be taken from each tested sheath. 8.4.3 Preparation of specimens
After all the sheaths are removed, the sheath shall be cut open along the axial direction, and then the insulating core, filler and other structural elements on the surface (if any) shall be removed.
If the inner and outer surfaces of the sheath are smooth and the average thickness does not exceed 2.0mm, the specimen does not need to be flattened or ground. Specimens with a thickness exceeding 2.0mm or specimens with brown mark indentations and indentations or ridges on the inner side shall be flattened or ground to obtain two smooth parallel surfaces, and their thickness shall not be greater than 2.0mm and not less than 0.8mm. If a 0.8mm specimen cannot be obtained from the original specimen, the minimum thickness allowed is 0.6mm. Care should be taken to avoid overheating and excessive mechanical damage during flattening or flattening. For an example of a cutting machine, see Appendix A of GB/T2951.1-1997. All specimens shall be stored at ambient temperature for at least 16 h. Afterwards, two dumbbell specimens as shown in Figure 3 or Figure 4 (if necessary) shall be punched out along the axial direction of each specimen. If possible, two dumbbell specimens shall be punched out side by side. If the distance between the marking lines is directly measured during the test, the marking lines shall be made on the dumbbell specimens in accordance with the last paragraph of Section 9, 1.3a) of GB/T2951.1-1997. 8.4.4 Test equipment In accordance with the provisions of Article 8.3.4. 8.4.5 Test procedures and test conditions In accordance with the provisions of Article 8.3.5, 8.4.6 Evaluation of test results In accordance with the provisions of Article 8.3.6.
8.5 Low temperature impact test on polyvinyl chloride insulation and sheath 8.5.1 Overview
This test is applicable to all types of polyvinyl chloride sheathed cables, regardless of the insulation type of the insulated core. If specified in the relevant cable product standards, it is also applicable to the polyvinyl chloride insulation of unsheathed wires, cords and fan-flat cords. The polyvinyl chloride insulation of sheathed cables is not directly subjected to low temperature impact test. 8.5.2 Sampling and specimen preparation
Take three finished cable specimens, each with a length of at least 5 times the cable diameter and a minimum of 150 mm. All outer sheaths should be removed. 8.5.3 Test equipment
GB/T 2951.4—1997
The equipment used for this test is shown in Figure 2, with annotations attached. The equipment should be placed on a sponge rubber pad about 40 mm thick and should be placed in a low temperature box before and during the test. 8.5.4 Test conditions
The test temperature should be specified by the relevant cable product standards. For fixed cable samples, the test weight shall be as specified in the following table: External diameter, nm
Less than or equal toWww.bzxZ.net
For samples of flexible cables, cords and communication cables, the test weight shall be as specified in the following table: External diameter, nm
For fan-shaped cords
Less than or equal to
The external diameters listed in the table shall be measured with a vernier caliper or measuring tape for each sample. When testing fan-shaped cords, the short axis shall be perpendicular to the steel base. 8.5.5 Test steps
Drop weight
The test equipment and the cable samples to be tested shall be placed side by side in a low temperature box and kept at the specified temperature for at least 16 hours, including the cooling time of the test equipment. If the test equipment has been pre-cooled and the sample has reached the specified test temperature, the cooling time may be shortened, but shall not be less than 1 hour.
After the specified cooling time, each sample shall be placed in the position shown in Figure 2 in turn, and the drop weight shall be dropped from a height of 100 mm. After the test, allow the specimen to return to near room temperature. Then check the insulation of the unsheathed cable or cord. Keep the specimen straight and twist it 360° every 100 mm. Then check the insulation. If the insulation cannot be twisted in this way, check it according to the provisions for the sheath. Before checking the sheath of the cable or cord, allow it to return to near room temperature and then immerse it in hot water. Then cut the sheath along the cable axis.
Check the inner and outer surfaces of the sheath and insulation. Only the outer surface of the insulation of the sheathed cable or cord is checked. 8.5.6 Evaluation of test results
When checked with normal vision or corrected vision without a magnifying glass, none of the three specimens should have cracks. If one of the three specimens has a crack, take three more specimens and repeat the test. If all three specimens have cracks, the test requirements are met. If any of the specimens still have cracks, the cable or sheath does not meet the test requirements. Balance block
1 sS-1.5 d3
2d -1.21, 5d
GB/T2951.4—1997
x about 30mm
Front view
View A
Regulation drawing (sample circumference)
3 In horizontal position (HP), the sample should not be pressed down too much. 4 In inclined position (S, P.), the sample should not be pointed up too much. Figure 1 Low temperature winding equipment
Shi Shige
GB/T 2951. 4 -- 1997
Yicheng sample
Steel base 1okg
Middle iron block 100g
Xuan inverted space
A cut surface
Figure 2 Impact test equipment
Marking line
Figure 3 Bell test piece
Dimension unit: mm
Dimension unit: mn
GB/T 2951. 4 -- 1997
Marking line
Small dumbbell test piece
Dimension unit: nm2 Sampling
Two specimens of appropriate length shall be taken from each tested sheath. 8.4.3 Preparation of specimens
After all the sheaths are removed, the sheath shall be cut open along the axial direction, and then the insulating core, filler and other structural elements on the surface (if any) shall be removed.
If the inner and outer surfaces of the sheath are smooth and the average thickness does not exceed 2.0mm, the specimen does not need to be flattened or ground. Specimens with a thickness exceeding 2.0mm or specimens with brown mark indentations and indentations or ridges on the inner side shall be flattened or ground to obtain two smooth parallel surfaces, and their thickness shall not be greater than 2.0mm and not less than 0.8mm. If a 0.8mm specimen cannot be obtained from the original specimen, the minimum thickness allowed is 0.6mm. Care should be taken to avoid overheating and excessive mechanical damage during flattening or flattening. For an example of a cutting machine, see Appendix A of GB/T2951.1-1997. All specimens shall be stored at ambient temperature for at least 16 h. Afterwards, two dumbbell specimens as shown in Figure 3 or Figure 4 (if necessary) shall be punched out along the axial direction of each specimen. If possible, two dumbbell specimens shall be punched out side by side. If the distance between the marking lines is directly measured during the test, the marking lines shall be made on the dumbbell specimens in accordance with the last paragraph of Section 9, 1.3a) of GB/T2951.1-1997. 8.4.4 Test equipment In accordance with the provisions of Article 8.3.4. 8.4.5 Test procedures and test conditions In accordance with the provisions of Article 8.3.5, 8.4.6 Evaluation of test results In accordance with the provisions of Article 8.3.6.
8.5 Low temperature impact test on polyvinyl chloride insulation and sheath 8.5.1 Overview
This test is applicable to all types of polyvinyl chloride sheathed cables, regardless of the insulation type of the insulated core. If specified in the relevant cable product standards, it is also applicable to the polyvinyl chloride insulation of unsheathed wires, cords and fan-flat cords. The polyvinyl chloride insulation of sheathed cables is not directly subjected to low temperature impact test. 8.5.2 Sampling and specimen preparation
Take three finished cable specimens, each with a length of at least 5 times the cable diameter and a minimum of 150 mm. All outer sheaths should be removed. 8.5.3 Test equipment
GB/T 2951.4—1997
The equipment used for this test is shown in Figure 2, with annotations attached. The equipment should be placed on a sponge rubber pad about 40 mm thick and should be placed in a low temperature box before and during the test. 8.5.4 Test conditions
The test temperature should be specified by the relevant cable product standards. For fixed cable samples, the test weight shall be as specified in the following table: External diameter, nm
Less than or equal to
For samples of flexible cables, cords and communication cables, the test weight shall be as specified in the following table: External diameter, nm
For fan-shaped cords
Less than or equal to
The external diameters listed in the table shall be measured with a vernier caliper or measuring tape for each sample. When testing fan-shaped cords, the short axis shall be perpendicular to the steel base. 8.5.5 Test steps
Drop weight
The test equipment and the cable samples to be tested shall be placed side by side in a low temperature box and kept at the specified temperature for at least 16 hours, including the cooling time of the test equipment. If the test equipment has been pre-cooled and the sample has reached the specified test temperature, the cooling time may be shortened, but shall not be less than 1 hour.
After the specified cooling time, each sample shall be placed in the position shown in Figure 2 in turn, and the drop weight shall be dropped from a height of 100 mm. After the test, allow the specimen to return to near room temperature. Then check the insulation of the unsheathed cable or cord. Keep the specimen straight and twist it 360° every 100 mm. Then check the insulation. If the insulation cannot be twisted in this way, check it according to the regulations for the sheath. Before checking the sheath of the cable or cord, allow it to return to near room temperature and then immerse it in hot water. Then cut the sheath along the cable axis.
Check the inner and outer surfaces of the sheath and insulation. Only the outer surface of the insulation of the sheathed cable or cord is checked. 8.5.6 Evaluation of test results
When checked with normal vision or corrected vision without a magnifying glass, none of the three specimens should have cracks. If one of the three specimens has cracks, take three more specimens and repeat the test. If all three specimens have cracks, the test requirements are met. If any of the specimens still have cracks, the cable or sheath does not meet the test requirements. Balance block
1 sS-1.5 d3
2d -1.21, 5d
GB/T2951.4—1997
x about 30mm
Front view
View A
Regulation drawing (sample circumference)
3 In horizontal position (HP), the sample should not be pressed down too much. 4 In inclined position (S, P.), the sample should not be pointed up too much. Figure 1 Low temperature winding equipment
Shi Shige
GB/T 2951. 4 -- 1997
Yicheng sample
Steel base 1okg
Middle iron block 100g
Xuan inverted space
A cut surface
Figure 2 Impact test equipment
Marking line
Figure 3 Bell test piece
Dimension unit: mm
Dimension unit: mn
GB/T 2951. 4 -- 1997
Marking line
Small dumbbell test piece
Dimension unit: nm5 Test steps
Drop weight
The test equipment and the cable sample to be tested shall be placed side by side in a low temperature box and kept at the specified temperature for at least 16 hours, including the cooling time of the test equipment. If the test equipment has been pre-cooled and the sample has reached the specified test temperature, the cooling time may be shortened, but shall not be less than 1 hour.
After the specified cooling time, each sample shall be placed in the position shown in Figure 2 in turn, and the drop weight shall be dropped from a height of 100mm. After the test, the sample shall be restored to near room temperature. Then check the insulation of the unsheathed cable or cord. Keep the sample straight, twist the sample 360° every 100mm, and then check the insulation. If the insulation test cannot be twisted in this way, check it according to the regulations for the sheath. Before checking the sheath of the cable or cord, it should be restored to near room temperature and then immersed in hot water, and then the sheath shall be cut along the cable axis.
Check the inner and outer surfaces of the sheath and insulation. Only the outer surface of the insulation of the sheathed cable or cord shall be checked. 8.5.6 Evaluation of test results
When inspected with normal or corrected vision without a magnifying glass, none of the three specimens shall have cracks. If one of the three specimens has cracks, three more specimens shall be taken and the test repeated. If all three specimens have cracks, the test requirements are met. If any of the specimens still has cracks, the cable or sheath does not meet the test requirements. Balance weight
1 sS-1.5 d3
2d -1.21, 5d
GB/T2951.4—1997
x about 30mm
Front view
View A
Regulation (specimen circumference)
3 In horizontal position (HP), the test specimen shall not be pressed down too much. 4 In tilted position (S, P.), the test specimen shall not be pointed up too much. Figure 1 Low temperature winding equipment
Shi Shige
GB/T 2951. 4 -- 1997
Yicheng sample
Steel base 1okg
Middle iron block 100g
Xuan inverted space
A cut surface
Figure 2 Impact test equipment
Marking line
Figure 3 Bell test piece
Dimension unit: mm
Dimension unit: mn
GB/T 2951. 4 -- 1997
Marking line
Small dumbbell test piece
Dimension unit: nm5 Test steps
Drop weight
The test equipment and the cable sample to be tested shall be placed side by side in a low temperature box and kept at the specified temperature for at least 16 hours, including the cooling time of the test equipment. If the test equipment has been pre-cooled and the sample has reached the specified test temperature, the cooling time may be shortened, but shall not be less than 1 hour.
After the specified cooling time, each sample shall be placed in the position shown in Figure 2 in turn, and the drop weight shall be dropped from a height of 100mm. After the test, the sample shall be restored to near room temperature. Then check the insulation of the unsheathed cable or cord. Keep the sample straight, twist the sample 360° every 100mm, and then check the insulation. If the insulation test cannot be twisted in this way, check it according to the regulations for the sheath. Before checking the sheath of the cable or cord, it should be restored to near room temperature and then immersed in hot water, and then the sheath shall be cut along the cable axis.
Check the inner and outer surfaces of the sheath and insulation. Only the outer surface of the insulation of the sheathed cable or cord shall be checked. 8.5.6 Evaluation of test results
When inspected with normal or corrected vision without a magnifying glass, none of the three specimens shall have cracks. If one of the three specimens has cracks, three more specimens shall be taken and the test repeated. If all three specimens have cracks, the test requirements are met. If any of the specimens still has cracks, the cable or sheath does not meet the test requirements. Balance weight
1 sS-1.5 d3
2d -1.21, 5d
GB/T2951.4—1997
x about 30mm
Front view
View A
Regulation (specimen circumference)
3 In horizontal position (HP), the test specimen shall not be pressed down too much. 4 In tilted position (S, P.), the test specimen shall not be pointed up too much. Figure 1 Low temperature winding equipment
Shi Shige
GB/T 2951. 4 -- 1997
Yicheng sample
Steel base 1okg
Middle iron block 100g
Xuan inverted space
A cut surface
Figure 2 Impact test equipment
Marking line
Figure 3 Bell test piece
Dimension unit: mm
Dimension unit: mn
GB/T 2951. 4 -- 1997
Marking line
Small dumbbell test piece
Dimension unit: nm
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