GB/T 2951.6-1997 General test methods for cable insulation and sheath materials Part 3: Specific test methods for polyvinyl chloride mixtures Section 1: High temperature pressure test - Cracking resistance test
Some standard content:
National Standard of the People's Republic of China
Common test methods for insulating and sheathing materlals of electric cables Part 3: Methods specific to PVC compounds Section one: Pressure test at high temperature-Test for resistance lo cracking 1 Scope
GB/T 2951. 6—1997
idt IEC 811-3-1:1985
No.1（1994）1st Amendment
GB/T 2951.1- ·94
GB/T 2951.16~2951.17—94
GB/T 2951. 31~2951. 32---94
GB/T2951 standard specifies the test methods for polymer insulation and sheath materials of distribution cables and communication cables, including marine cables.
GB/T2951.6 specifies the temperature pressure test method and the crack resistance test method. Applicable to the insulation and sheath of ethylene materials for wires and cables.
2 Test principles
This standard does not specify all test conditions (such as temperature, duration, etc.) and all test requirements, which are specified in the relevant cable product standards.
Any test requirements specified in this standard can be modified in the relevant relay 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 general cables, wires and cords. 4 Type tests and other tests
The test methods described in this standard are first 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 pointed out these differences. 5 Pretreatment
All tests should be carried out after the insulation and sheath materials are extruded or vulcanized (or cross-linked) and stored for at least 16 hours. 6 Test temperature
Unless otherwise specified, the test should be carried out at ambient temperature. State Bureau of Technical Supervision approved 1998-1001 for implementation on October 28, 1997
7 Intermediate value
GB/T2951.6—1997
Arrange the test data with a certain number 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. 8 High temperature pressure test of insulation and sheath
Note: This test method is not recommended for insulation and sheath with a thickness of less than 0.4.mm. 8.1 Insulation high temperature pressure test
8.1.1 Sampling
For each insulated core to be tested, three adjacent specimens shall be cut from each sample section of 250 to 500 mm in length. The specimen length shall be 50 to 100 mm.
The insulated core of the unsheathed flat cord shall not be separated. 8.1.2 Preparation of specimens
All the coverings on the specimens, including the semiconductive layer (if any), shall be removed mechanically. Depending on the type of cable, the specimen may be of shaped or sectoral cross-section.
8.1.3 Placement of specimens
The indentation device is shown in Figure 1 and consists of a rectangular blade with a blade thickness of (0.70 ± 0.01) mm, which can apply pressure to the specimen. Each specimen is placed in the position shown in Figure 1. The unsheathed flat cord shall be placed with its flat side. The fixing method on the support plate of the small diameter specimen shall not cause the specimen to bend under the pressure of the blade. The sector specimen shall be placed on a support plate with a sector groove as shown in Figure 1, and pressure shall be applied in a direction perpendicular to the axis of the specimen. The blade shall also be perpendicular to the axis of the specimen. 8.1.4 Calculation of pressure
The pressure F exerted by the blade on the round and sector-shaped insulated core of the specimen, in N, shall be calculated as follows: F g 2 D#-
Where: - coefficient specified in the relevant cable product standard. If not specified, it shall be: Insulated core of flexible cord and flexible cable
D≤15mm insulated core of fixed laying cable D>15mm insulated core of fixed laying cable and sector-shaped insulated core ~ - average value of the thickness of the insulating specimen.
D——average value of the outer diameter of the specimen.
Table = 0. 7
and D are both in mm, to one decimal place. According to the test method specified in GB/T2951.1, it is measured on a thin slice cut from the end of the specimen.
For fan-shaped cores, D is the average diameter of the fan-shaped "back" or rounded part. The average value is measured three times on the cable core with a measuring tape, in mm, to one decimal place (the measurement should be carried out at three different places on the cable). The pressure acting on the unsheathed flat flexible wire sample should be twice the value calculated according to the above formula, where D is the average value of the minor axis size of the sample described in Article 8.1.1.
The calculated value of pressure F can be rounded to a smaller value, and the lower value rounded off should not exceed 3%. 8.1.5 Sample heating
The test should be carried out in an air oven, and the test equipment and samples should not vibrate in the oven, or placed in an air oven with an anti-vibration bracket. Any equipment that may cause the sample to vibrate, such as a blower, is not allowed to come into direct contact with the oven. The air temperature in the oven should always be maintained at the temperature specified in the relevant cable product standards. The time for placing the unpreheated pressure test specimen in the oven shall be in accordance with the relevant cable product standards. If there is no provision in the cable product standards, the following provisions shall apply:
4 h for the outer diameter of the specimen D≤15 mm; 6 h for the outer diameter of the specimen D>15 mm
8.1.6 Cooling of specimens
After the heating time specified in GB/T 2951. 6 1997 (see 8.1.5), the specimen shall be cooled rapidly under pressure in the oven. The specimen under pressure may be cooled by spraying cold water on it.
After the insulation specimen is cooled to the point where it overflows and no longer deforms, it shall be taken out of the test device and then immersed in cold water for further cooling. 8.1.7 Indentation measurement
Measure the indentation depth immediately after the specimen has cooled. Pull out the conductor and leave the tubular insulation sample. Cut a narrow tea test piece from the sample along the axis of the sample and perpendicular to the indentation, as shown in Figure 2. Place the narrow test piece flat under the reading microscope or measuring projector, and adjust the crosshairs to the bottom of the indentation and the outside of the test piece (as shown in circle 2). Small samples with an outer diameter of about 6 mm or less should cut two test pieces horizontally at the indentation and near the indentation (as shown in Figure 3). The indentation depth should be the difference between the measured values of profile 1 and profile 2 under the microscope (as shown in Figure 3). All measurements are in mm to two decimal places. 8.1.8 Evaluation of test results The median value of the indentation measured on the three test pieces cut from each sample should not be greater than 50% of the average value of the insulation thickness of the sample (measured in accordance with 8.1.4). Note that the value of 50 is related to the basic principle of the formula and is the same for all materials. The severity of the test varies only with the coefficient, but the value of 50% remains unchanged.
8.2 High-temperature stress test on sheaths
8.2.1 Detailed sampling
For each sheath to be tested, three adjacent specimens are cut from a sample section L of 250 to 500 mm in length after removing the outer sheath (if any) and all internal components (core, filler, inner sheath, armor, etc., if any). The length of the specimen should be 50 to 100 mm (the larger value is taken for the larger diameter). 8.2.2 Preparation of specimens
If there is no ridge in the sheath, a narrow strip with a width of about one-third of the circumference is cut from each sheath specimen (see 8.2.1) in the direction of the cable axis.
If the ridge in the sheath is caused by more than 5 insulated cores, a narrow strip should be cut in the same way and the ridge should be ground off. If the ridge inside the sheath is caused by 5 or fewer insulated cores, a narrow strip should be cut along the ridge direction, with at least one groove approximately in the middle of the strip.
If the sheath is directly covered on the concentric conductor, armor or metal shield, the ridge formed by this cannot be ground or cut off (except for large diameter), then it is not necessary to remove the sheath surface and use the entire cable section as a sample. 8.2.3 Position of the sample in the test device
The indentation device is the same as that specified in Article 8.1.3.As shown in Figure 1. Narrow strip application: "Supported by metal rods or metal tubes, the metal rods or metal tubes can be split in half along their own axis direction for more stable support. The radius of the metal tube or metal rod is approximately equal to half of the inner diameter of the specimen. The placement of the test equipment, narrow strips and support rods (tubes) should make the metal rod support the narrow strips, and the blade presses the outer surface of the specimen. Apply pressure in a direction perpendicular to the axis of the metal rod or metal tube (or when using a whole section of cable) and the cable, and make the blade perpendicular to the axis of the specimen. 8.2.4 Calculation of pressure Unless otherwise specified, the pressure F exerted by the blade on each sheath specimen, in N, should be calculated as follows: F = 2D8-
Wherein, there is a coefficient specified in the US cable product standard. If not specified, it should be: Soft cord and flexible cable GB/T 2951. 6—1997
D≤15mm fixed digital cable
D>15mm fixed laying cable
3—Average value of sheath sample thickness.
路=0, 7
刀—Average value of outer diameter of sheath sample. For flat cable or soft wire, it is the average value of the short axis size of sheath sample. Both D and D are in mm, to the decimal place, measured according to the test method specified in Chapter 8 of GB/T2951.1-1997 (D is the diameter of the cable from which the sample is cut). The calculated value of pressure F can be rounded to a smaller value. However, the included value should not exceed 3%. 8.2.5 Sample heating
The sample should be heated according to the method specified in Article 8.1.5, and the time should be in accordance with the provisions of the relevant cable product standards. If there are provisions, it should be: - 4h when the outer diameter of the sample D≤15mm;
- 6h when the outer diameter of the sample D>15 mm h. 8.2.6 Cooling of the specimen
The specimen shall be cooled in accordance with the method specified in 8.1.6. 8.2.7 Indentation measurement
The indentation shall be measured in accordance with the method specified in 8.1.7 on a test piece cut from the specimen, as shown in Figure 2. 8.2.8 Determination of test results
The median value of the indentation measured on the three test pieces cut from the test jacket specimen shall not be greater than 50% of the average value of the jacket test thickness measured in accordance with 8.2.4.
Note: The value of 50% is related to the basic principle of the formula and is the same for all materials. The severity of the test only changes with the change in the coefficient table, but the value of 50% remains unchanged. ||tt| |8.3 Test method for pointer micrometer
Under consideration.
9 Insulation and sheath cracking resistance test
9.1 Insulation thermal shock test
9.1.1 Sampling
Two specimens of appropriate length shall be taken from each insulated core to be tested. The specimens shall be taken from two locations with an interval of at least 1 Ⅱ. If there is an outer sheath, it shall be removed from the insulation. 9.1.2 Preparation of specimens
The specimens shall be prepared in one of the following three ways: a) For insulated cores with an outer diameter not exceeding 12.5 mm, each specimen shall be a section of insulated core. b) For insulated cores with an outer diameter exceeding 12.5 mm and an insulation thickness not exceeding 5.0 mm and all sector-shaped insulated cores, each specimen shall be a narrow strip of insulation with a width of at least 1.5 times the insulation thickness but not less than 4 mm. The strips shall be cut along the axis of the insulated core. If it is a flat insulated core, it shall be cut at the back of the insulated core. c) For insulated cores with an outer diameter exceeding 12.5 mm and an insulation thickness exceeding 5.0 mm, each specimen shall be cut into a strip as specified in b), and then the outer surface of the strip shall be ground or shaved (to avoid overheating) to a thickness of 4.0 to 5.0 mm. The thickness shall be measured at the thicker part of the strip. The width of the strip shall be at least 1.5 times the thickness.
9.1.3 Specimen Winding
Each specimen shall be tightly wound into a spiral on the test rod at ambient temperature, with both ends fixed. The test rod diameter and number of windings are specified as follows: a) Table 1 applies to specimens prepared according to 9.1.2a); for flat cables and cords, the diameter of the test rod shall be selected according to the size of its minor axis, and the minor axis shall be perpendicular to the test rod during winding.
b) Table 2 applies to the specimens prepared according to 9.1.2 h) and c). In this case, the inner surface of the specimen shall be in contact with the test rod. Specimen outer diameter D, mm
6.5-0≤9.5
9.5≤0≤12. 5
Specimen thickness a.mm
GB/T2951.6--1997
Test rod diameter, mm
Test rod diameter, mm
In the above table, the specimen or thickness shall be measured with a vernier caliper or other suitable measuring tool. 9.1.4 Heating inspection
Number of windings
Number of winding turns
The specimen wound on the test rod 1: shall be placed in an air oven preheated to the test temperature specified in the relevant cable product standard. If the cable standard does not specify, preheat to (150 ± 3)℃. The specimen shall be kept at the specified temperature for 1h. When the sample reaches the approximate ambient temperature, check the sample still on the test rod. 9.1.5 Evaluation of test results
When the sample is checked with normal or corrected vision without a magnifying glass, there should be no cracks. 9.2 Sheath thermal shock test
Two cable samples of appropriate length should be taken from each tested sheath. The samples are taken from two places with a distance of at least 1m. All outer sheaths should be removed.
9.2.2 Preparation of samples
a) For sheaths with an outer diameter not exceeding 12.5mm, each sample should be a section of cable, except for polyolefin insulated and vinyl chloride sheathed cables.
b) For sheaths with an outer diameter exceeding 12.5mm and a thickness not exceeding 5.0mm and for sheaths of polyethylene insulated cables, each sample should be a narrow strip taken from the sheath, with a width of at least 1.5 times the sheath diameter but not less than 4mm. The narrow strip should be cut along the axial direction of the cable. c) For sheaths with an outer diameter exceeding 12.5mm and a thickness exceeding 5.0mm, each sample shall be a strip cut according to the provisions of b), and then ground or shaved (avoid overheating) on the outer surface of the strip to a thickness of 4.0~-5.0mm. The thickness shall be measured at the thicker part of the strip, and the thickness of the strip shall be at least 1.5 times the thickness.
d) For dry fan cables, if the cable width does not exceed 12.5mm, each sample shall be a complete section of cable. If the cable width exceeds 12.5 mm, each sample shall be a narrow strip cut from the sheath as specified in b). 9.2.3 Test winding
Angle · Each sample shall be tightly wound into a spiral on the test rod at ambient temperature, and the two ends shall be fixed. The test point diameter and number of winding turns are: for the war sample prepared in accordance with 9.2.2a), see the provisions of 9.1.3a); for the test sample prepared in accordance with 9.2.2b) and c>, see the provisions of 9.1.36). The diameter or thickness of the sample shall be measured with a vernier caliper or other suitable measuring tool. 9.2.4 Heating and inspection
According to the provisions of 9.1.4,
9.2.5 Evaluation of test results
According to the provisions of 9.1.5,
GB/T 2951. 61997
main 0.012n
1-rectangular tool; 2-sample; 3g, 3h, 3c-sample holder; 4-loadFig.1 Indentation device
Cut piece
Cross section under microscope
Fig.2 Compression attenuation measurement
Cross line of microscope
Under measuring system
Fig.3 Indentation measurement of small sample1-1997 Chapter 8 test method (D is the diameter of the cable from which the sample is cut). The calculated value of pressure F can be rounded to a smaller value. However, the included value should not exceed 3%. 8.2.5 Sample heating
The sample should be heated according to the method specified in Article 8.1.5, and the time should be in accordance with the provisions of the relevant cable product standards. If there are any regulations, they should be: - 4 hours when the outer diameter of the sample D ≤ 15 mm;
- 6 hours when the outer diameter of the sample D> 15 mm. 8.2.6 Sample cooling
The sample should be cooled according to the method specified in Article 8.1.6. 8.2.7 Indentation measurement
The indentation should be measured on the test piece cut from the sample according to the method specified in Article 8.1.7, as shown in Figure 2. 8.2.8 Determination of test results
The median value of the indentation measured on three test pieces cut from the test sheath specimen shall not exceed 50% of the average value of the sheath test thickness measured in accordance with 8.2.4.
Note: The value of 50% is related to the basic principle of the formula and is the same for all materials. The severity of the test varies only with the change in the coefficient table, but the value of 50% remains unchanged.
8.3 Test method for pointer micrometer
Under consideration.
9 Test for cracking resistance of insulation and sheath
9.1 Test for thermal shock of insulation
9.1.1 Sampling
Two specimens of appropriate length shall be taken from each insulated core to be tested. The specimens shall be taken from two places with an interval of at least 1 Ⅱ. If there is an outer sheath, it shall be removed from the insulation. 9.1.2 Preparation of test specimens
Test specimens shall be prepared in one of the following three ways: a) For insulated wire cores with an outer diameter not exceeding 12.5 mm, each test specimen shall be a section of insulated wire core. b) For insulated wire cores with an outer diameter exceeding 12.5 mm and an insulation thickness not exceeding 5.0 mm and all fan-shaped insulated wire cores, each test specimen shall be a narrow strip of insulation, the width of which shall be at least 1.5 times the insulation thickness but not less than 4 mm. The strip shall be cut along the axis of the insulated wire core, and in the case of fan-shaped insulated wire cores, it shall be cut from the back of the insulated wire core. c) For insulated wire cores with an outer diameter exceeding 12.5 mm and an insulation thickness exceeding 5.0 mm, each test specimen shall be cut into a narrow strip as specified in b), and then the outer surface of the strip shall be ground or shaved (to avoid overheating) to a thickness of 4.0~5.0 mm, which shall be measured at the thicker part of the strip. The width of the strip shall be at least 1.5 times the thickness.
9.1.3 Specimen Winding
Each specimen shall be tightly wound into a spiral shape on the test rod at ambient temperature, with both ends fixed. The test rod diameter and number of windings are specified as follows: a) Table 1 applies to specimens prepared in accordance with 9.1.2a); for flat cables and cords, the test rod diameter shall be selected according to its minor axis size, and the minor axis shall be perpendicular to the test rod during winding.
b) Table 2 applies to specimens prepared in accordance with 9.1.2h) and c). In this case, the inner surface of the specimen shall be in contact with the test rod. Sample outer diameter D, mm
6.5-0≤9.5
9.5≤0≤12. 5
Sample thickness a. mm
GB/T2951.6--1997
Test ladder diameter, mm
Test ladder diameter, mm
In the above table, the sample or thickness shall be measured with a vernier caliper or other suitable measuring tools. 9.1.4 Heating inspection
Number of windings
Number of winding turns
The sample wound on the test rod 1: should be placed in an air oven preheated to the test temperature specified in the relevant cable product standard. If the cable standard does not specify, preheat to (150 ± 3) ℃. The sample is kept at the specified temperature for 1h. When the sample reaches the approximate ambient temperature, check the sample still on the test rod. 9.1.5 Evaluation of test results
When inspected with normal or corrected vision without a magnifying glass, the specimen shall be free of cracks. 9.2 Sheath thermal shock test
Two cable specimens of appropriate length shall be taken from each tested sheath, and the specimens shall be taken from two locations with a minimum interval of 1 m. All outer sheaths shall be removed.
9.2.2 Preparation of specimens
a) For sheaths with an outer diameter not exceeding 12.5 mm, each specimen shall be a section of cable, except for polyolefin insulated and vinyl chloride sheathed cables.
b) For sheaths with an outer diameter exceeding 12.5 mm and a thickness not exceeding 5.0 mm and for sheaths of polyethylene insulated cables, each specimen shall be a narrow strip taken from the sheath, with a width of at least 1.5 times the sheath length but not less than 4 mm. The narrow strip shall be cut along the axial direction of the cable. c) For sheaths with an outer diameter exceeding 12.5mm and a thickness exceeding 5.0mm, each sample shall be a strip cut according to the provisions of b), and then ground or shaved (avoid overheating) on the outer surface of the strip to a thickness of 4.0~-5.0mm. The thickness shall be measured at the thicker part of the strip, and the thickness of the strip shall be at least 1.5 times the thickness.
d) For dry fan cables, if the cable width does not exceed 12.5mm, each sample shall be a complete section of cable. If the cable width exceeds 12.5 mm, each sample shall be a narrow strip cut from the sheath as specified in b). 9.2.3 Test winding
Angle · Each sample shall be tightly wound into a spiral on the test rod at ambient temperature, and the two ends shall be fixed. The test point diameter and number of winding turns are: for the war sample prepared in accordance with 9.2.2a), see the provisions of 9.1.3a); for the test sample prepared in accordance with 9.2.2b) and c>, see the provisions of 9.1.36). The diameter or thickness of the sample shall be measured with a vernier caliper or other suitable measuring tool. 9.2.4 Heating and inspection
According to the provisions of 9.1.4,
9.2.5 Evaluation of test results
According to the provisions of 9.1.5,
GB/T 2951. 61997
main 0.012n
1-rectangular tool; 2-sample; 3g, 3h, 3c-sample holder; 4-loadFig.1 Indentation device
Cut piece
Cross section under microscope
Fig.2 Compression attenuation measurement
Cross line of microscope
Under measuring system
Fig.3 Indentation measurement of small sample1-1997 Chapter 8 test method (D is the diameter of the cable from which the sample is cut). The calculated value of pressure F can be rounded to a smaller value. However, the included value should not exceed 3%. 8.2.5 Sample heating
The sample should be heated according to the method specified in Article 8.1.5, and the time should be in accordance with the provisions of the relevant cable product standards. If there are any regulations, they should be: - 4 hours when the outer diameter of the sample D ≤ 15 mm;
- 6 hours when the outer diameter of the sample D> 15 mm. 8.2.6 Sample cooling
The sample should be cooled according to the method specified in Article 8.1.6. 8.2.7 Indentation measurement
The indentation should be measured on the test piece cut from the sample according to the method specified in Article 8.1.7, as shown in Figure 2. 8.2.8 Determination of test results
The median value of the indentation measured on three test pieces cut from the test sheath specimen shall not exceed 50% of the average value of the sheath test thickness measured in accordance with 8.2.4.
Note: The value of 50% is related to the basic principle of the formula and is the same for all materials. The severity of the test varies only with the change in the coefficient table, but the value of 50% remains unchanged.
8.3 Test method for pointer micrometer
Under consideration.
9 Test for cracking resistance of insulation and sheath
9.1 Test for thermal shock of insulation
9.1.1 Sampling
Two specimens of appropriate length shall be taken from each insulated core to be tested. The specimens shall be taken from two places with an interval of at least 1 Ⅱ. If there is an outer sheath, it shall be removed from the insulation. 9.1.2 Preparation of test specimens
Test specimens shall be prepared in one of the following three ways: a) For insulated wire cores with an outer diameter not exceeding 12.5 mm, each test specimen shall be a section of insulated wire core. b) For insulated wire cores with an outer diameter exceeding 12.5 mm and an insulation thickness not exceeding 5.0 mm and all fan-shaped insulated wire cores, each test specimen shall be a narrow strip of insulation, the width of which shall be at least 1.5 times the insulation thickness but not less than 4 mm. The strip shall be cut along the axis of the insulated wire core, and in the case of fan-shaped insulated wire cores, it shall be cut from the back of the insulated wire core. c) For insulated wire cores with an outer diameter exceeding 12.5 mm and an insulation thickness exceeding 5.0 mm, each test specimen shall be cut into a narrow strip as specified in b), and then the outer surface of the strip shall be ground or shaved (to avoid overheating) to a thickness of 4.0~5.0 mm, which shall be measured at the thicker part of the strip. The width of the strip shall be at least 1.5 times the thickness.
9.1.3 Specimen Winding
Each specimen shall be tightly wound into a spiral shape on the test rod at ambient temperature, with both ends fixed. The test rod diameter and number of windings are specified as follows: a) Table 1 applies to specimens prepared in accordance with 9.1.2a); for flat cables and cords, the test rod diameter shall be selected according to its minor axis size, and the minor axis shall be perpendicular to the test rod during winding.
b) Table 2 applies to specimens prepared in accordance with 9.1.2h) and c). In this case, the inner surface of the specimen shall be in contact with the test rod. Sample outer diameter D, mm
6.5-0≤9.5
9.5≤0≤12. 5
Sample thickness a. mm
GB/T2951.6--1997
Test ladder diameter, mm
Test ladder diameter, mm
In the above table, the sample or thickness shall be measured with a vernier caliper or other suitable measuring tools. 9.1.4 Heating inspection
Number of windings
Number of winding turns
The sample wound on the test rod 1: should be placed in an air oven preheated to the test temperature specified in the relevant cable product standard. If the cable standard does not specify, preheat to (150 ± 3) ℃. The sample is kept at the specified temperature for 1h. When the sample reaches the approximate ambient temperature, check the sample still on the test rod. 9.1.5 Evaluation of test results
When inspected with normal or corrected vision without a magnifying glass, the specimen shall be free of cracks. 9.2 Sheath thermal shock test
Two cable specimens of appropriate length shall be taken from each tested sheath, and the specimens shall be taken from two locations with a minimum interval of 1 m. All outer sheaths shall be removed.
9.2.2 Preparation of specimens
a) For sheaths with an outer diameter not exceeding 12.5 mm, each specimen shall be a section of cable, except for polyolefin insulated and vinyl chloride sheathed cables.
b) For sheaths with an outer diameter exceeding 12.5 mm and a thickness not exceeding 5.0 mm and for sheaths of polyethylene insulated cables, each specimen shall be a narrow strip taken from the sheath, with a width of at least 1.5 times the sheath length but not less than 4 mm. The narrow strip shall be cut along the axial direction of the cable. c) For sheaths with an outer diameter exceeding 12.5mm and a thickness exceeding 5.0mm, each sample shall be a strip cut according to the provisions of b), and then ground or shaved (avoid overheating) on the outer surface of the strip to a thickness of 4.0~-5.0mm. The thickness shall be measured at the thicker part of the strip, and the thickness of the strip shall be at least 1.5 times the thickness.
d) For dry fan cables, if the cable width does not exceed 12.5mm, each sample shall be a complete section of cable. If the cable width exceeds 12.5 mm, each sample shall be a narrow strip cut from the sheath as specified in b). 9.2.3 Test winding
Angle · Each sample shall be tightly wound into a spiral on the test rod at ambient temperature, and the two ends shall be fixed. The test point diameter and number of winding turns are: for the war sample prepared in accordance with 9.2.2a), see the provisions of 9.1.3a); for the test sample prepared in accordance with 9.2.2b) and c>, see the provisions of 9.1.36). The diameter or thickness of the sample shall be measured with a vernier caliper or other suitable measuring tool. 9.2.4 Heating and inspection
According to the provisions of 9.1.4,
9.2.5 Evaluation of test results
According to the provisions of 9.1.5,
GB/T 2951. 61997
main 0.012n
1-rectangular tool; 2-sample; 3g, 3h, 3c-sample holder; 4-loadFig.1 Indentation device
Cut piece
Cross section under microscope
Fig.2 Compression attenuation measurement
Cross line of microscope
Under measuring system
Fig.3 Indentation measurement of small sample2a) prepared; for flat cables and cords, the diameter of the test rod shall be selected according to the size of its minor axis, and the minor axis shall be perpendicular to the test rod when winding.
b) Table 2 applies to the samples prepared according to 9.1.2 h) and c). In this case, the inner surface of the sample shall be in contact with the test rod. Sample outer diameter D, mm
6.5-0≤9.5
9.5≤0≤12. 5
Sample thickness a.mm
GB/T2951.6--1997
Test ladder diameter, mm
Test ladder diameter, mm
In the above table, the sample or thickness shall be measured with a vernier caliper or other suitable measuring tool. 9.1.4 Heating inspection
Number of windings
Number of winding turns
The sample wound on the test rod 1: should be placed in an air oven preheated to the test temperature specified in the relevant cable product standard. If the cable standard does not specify, preheat to (150 ± 3)℃. The sample is kept at the specified temperature for 1h. When the sample reaches the approximate ambient temperature, check the sample still on the test rod. 9.1.5 Evaluation of test results
When inspected with normal vision or corrected vision without a magnifying glass, the sample should be free of cracks. 9.2 Sheath thermal shock test
Two cable samples of appropriate length should be taken for each tested sheath. The samples are taken from two places with a distance of at least 1m. All outer sheaths should be removed.
9.2.2 Preparation of test specimens
a) For sheaths with an outer diameter not exceeding 12.5 mm, each test specimen shall be a section of cable, except for polyolefin insulated and vinyl chloride sheathed cables.
b) For sheaths with an outer diameter exceeding 12.5 mm and a thickness not exceeding 5.0 mm and for sheaths of polyethylene insulated cables, each test specimen shall be a narrow strip taken from the sheath, the width of which shall be at least 1.5 times the sheath thickness but not less than 4 mm. The narrow strip shall be cut along the axial direction of the cable. c) For sheaths with an outer diameter exceeding 12.5 mm and a thickness exceeding 5.0 mm, each test specimen shall be a narrow strip cut according to the provisions of b), and then ground or shaved (avoid overheating) on the outer surface of the narrow strip to a thickness of 4.0~-5.0 mm. The thickness shall be measured from the thicker part of the strip, and the width of the narrow strip shall be at least 1.5 times the thickness.
d) For dry fan cables, if the cable width does not exceed 12.5mm, each sample should be a complete cable. If the cable width exceeds 12.5mm, each sample should be a narrow strip cut from the sheath according to b). 9.2.3 Test winding bzxZ.net
Angle Each sample should be tightly wound into a spiral on the test rod at ambient temperature, and the two ends should be fixed. The test point diameter and number of windings are: for the war sample prepared in accordance with 9.2.2a), see the provisions of 9.1.3a); for the test sample prepared in accordance with 9.2.2b) and c>, see the provisions of 9.1.36). The diameter or thickness of the sample should be measured with a vernier caliper or other suitable measuring tools. 9.2.4 Heating and inspection
According to the provisions of 9.1.4,
9.2.5 Evaluation of test results
According to the provisions of 9.1.5,
GB/T 2951. 61997
main 0.012n
1-rectangular tool; 2-sample; 3g, 3h, 3c-sample holder; 4-loadFig.1 Indentation device
Cut piece
Cross section under microscope
Fig.2 Compression attenuation measurement
Cross line of microscope
Under measuring system
Fig.3 Indentation measurement of small sample2a) prepared; for flat cables and cords, the diameter of the test rod shall be selected according to the size of its minor axis, and the minor axis shall be perpendicular to the test rod when winding.
b) Table 2 applies to the samples prepared according to 9.1.2 h) and c). In this case, the inner surface of the sample shall be in contact with the test rod. Sample outer diameter D, mm
6.5-0≤9.5
9.5≤0≤12. 5
Sample thickness a.mm
GB/T2951.6--1997
Test ladder diameter, mm
Test ladder diameter, mm
In the above table, the sample or thickness shall be measured with a vernier caliper or other suitable measuring tool. 9.1.4 Heating inspection
Number of windings
Number of winding turns
The sample wound on the test rod 1: should be placed in an air oven preheated to the test temperature specified in the relevant cable product standard. If the cable standard does not specify, preheat to (150 ± 3)℃. The sample is kept at the specified temperature for 1h. When the sample reaches the approximate ambient temperature, check the sample still on the test rod. 9.1.5 Evaluation of test results
When inspected with normal vision or corrected vision without a magnifying glass, the sample should be free of cracks. 9.2 Sheath thermal shock test
Two cable samples of appropriate length should be taken for each tested sheath. The samples are taken from two places with a distance of at least 1m. All outer sheaths should be removed.
9.2.2 Preparation of test specimens
a) For sheaths with an outer diameter not exceeding 12.5 mm, each test specimen shall be a section of cable, except for polyolefin insulated and vinyl chloride sheathed cables.
b) For sheaths with an outer diameter exceeding 12.5 mm and a thickness not exceeding 5.0 mm and for sheaths of polyethylene insulated cables, each test specimen shall be a narrow strip taken from the sheath, the width of which shall be at least 1.5 times the sheath thickness but not less than 4 mm. The narrow strip shall be cut along the axial direction of the cable. c) For sheaths with an outer diameter exceeding 12.5 mm and a thickness exceeding 5.0 mm, each test specimen shall be a narrow strip cut according to the provisions of b), and then ground or shaved (avoid overheating) on the outer surface of the narrow strip to a thickness of 4.0~-5.0 mm. The thickness shall be measured from the thicker part of the strip, and the width of the narrow strip shall be at least 1.5 times the thickness.
d) For dry fan cables, if the cable width does not exceed 12.5mm, each sample should be a complete cable. If the cable width exceeds 12.5mm, each sample should be a narrow strip cut from the sheath according to b). 9.2.3 Test winding
Angle Each sample should be tightly wound into a spiral on the test rod at ambient temperature, and the two ends should be fixed. The test point diameter and number of windings are: for the war sample prepared in accordance with 9.2.2a), see the provisions of 9.1.3a); for the test sample prepared in accordance with 9.2.2b) and c>, see the provisions of 9.1.36). The diameter or thickness of the sample should be measured with a vernier caliper or other suitable measuring tools. 9.2.4 Heating and inspection
According to the provisions of 9.1.4,
9.2.5 Evaluation of test results
According to the provisions of 9.1.5,
GB/T 2951. 61997
main 0.012n
1-rectangular tool; 2-sample; 3g, 3h, 3c-sample holder; 4-loadFig.1 Indentation device
Cut piece
Cross section under microscope
Fig.2 Compression attenuation measurement
Cross line of microscope
Under measuring system
Fig.3 Indentation measurement of small sample
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