GB/T 2951.1-1997 General test methods for cable insulation and sheath materials Part 1: General test methods Section 1: Thickness and overall dimensions measurement - Mechanical properties test
Some standard content:
National Standard of the People's Republic of China
Common test methods for insulating and sheathing materials of electric cablesPart 1:Methods for general applicationSection one : Measurement of thickuess and overalldimensionB-Tests for determlnlng the mechanical properties1Scope
GB/T 2951. 1—1997
idt IEC 811-1-1:1993
Replaces GB/T 2951.1-~2951. 6—-94GB/T2951 standard specifies the test methods for polymer insulation and sheathing materials of distribution cables and communication cables, including shipboard cables.
GB/T2951.1 specifies the measurement methods of thickness and dimensions and the test methods of mechanical properties. These methods are applicable to the most common types of insulation and sheath materials (elastomers, polyvinyl chloride, mulberry, polypropylene, etc.). 1. 1 Referenced standards
The provisions contained in the following standards constitute the provisions of this standard through reference in this standard. When this standard is published, the versions shown are valid. All standards will be revised, and parties using this standard should explore the possibility of using the latest versions of the following standards. GB/T2951.2-1997 General test methods for cable insulation and sheathing materials Part 1: General test methods Section 2: Heat aging test methods
GB/T2951.3-1997 General test methods for cable insulation and sheathing materials Part 1: General test methods Section 3: Density determination method - Water absorption test - Shrinkage test GB/T 2951.5-1997
General test methods for cable insulation and sheathing materials Part 2: Special test methods for elastomeric mixtures Section 1: Ozone resistance test - Hot extension test - Mineral oil immersion test 2 Test principles
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. Approved by the State Administration of Technical Supervision on October 28, 1997 and implemented on October 1, 1998
4 Type test and other tests
GB/T 2951. 1-1997
The test methods specified in this standard are first used as type tests. The conditions of some test items are essentially different from those of regular tests (such as routine tests). This standard has pointed out these differences. 5 Pretreatment
All tests should be carried out after the insulation and sheath materials have been stored for at least 16 hours after extrusion or vulcanization (or cross-linking). Unless otherwise specified, all samples, including aged or card-aged samples, should be kept at a temperature of (23 ± 5) for at least 3 hours before any test. 6 Test temperature
Unless otherwise specified, the test should be carried out at ambient temperature. 7 Definitions
This standard adopts the following definitions:
7.1 Maximum tensile force: the maximum value reached by the load during the test. 7.2 Tensile stress: the tensile force per unit area of the specimen when it is not stretched. 7.3 Tensile strength: the maximum tensile stress recorded when the specimen is stretched to fracture. 7.4 Elongation at break: the percentage of the increment of the marked distance when the specimen is stretched to fracture to the marked distance of the unstretched specimen. 7.5 Middle value: the obtained test data are arranged in increasing or decreasing order. When the number of valid data is an even number, the middle value is the middle value; if it is an even number, the middle value is the average of the two middle values. 8 Measurement of thickness and dimensions
8.1 Measurement of insulation thickness
8.1.1 Overview
The measurement of insulation thickness can be used as a separate test or as a step in other tests such as mechanical properties test.
In all cases, the sampling method shall comply with the provisions of the relevant cable product standards. 8.1.2 Measuring device
A reading microscope or a photometer with a magnification of at least 10 times. Both devices have readings to 0.01mm. When the insulation thickness is less than 0.5mm, the third decimal place is an estimated reading. In case of dispute, the reading microscope measurement should be used as the basic method. 8.1.3 Sample preparation
Remove all protective layers from the insulation, and pull out the conductor and the isolation layer (if any). Be careful not to damage the insulation. If the inner and outer semi-conductive layers are adhered to the insulation, they do not need to be removed. Each test piece consists of an insulating sheet. An appropriate tool (sharp blade such as a razor blade, etc.) should be used to close the sheet along a plane perpendicular to the conductor axis.
The core of the unsheathed flat cord should not be separated. If the insulation has a dent with a pressure mark, the thickness at that place will become thinner, so the test piece should take the section containing the mark. 8.1.4 Measurement steps
Place the test piece on the working surface of the measuring device, with the cutting surface perpendicular to the optical axis. a) When the inner side of the test piece is circular, the 6 points should be measured radially according to Figure 1. If it is a shaped insulated core, measure 6 points according to Figure 2. b) When the insulation is cut from a stranded conductor, 6 points should be measured radially according to Figures 3 and 1. c) When the outer surface of the test piece is uneven, 6 points should be measured according to Figure 5. GB/T2951.1—1997
d) When there are non-removable shielding layers inside and outside the insulation, the thickness of the shielding layer should be subtracted from the measured value. When there are non-removable shielding layers inside and outside the opaque insulation, a reading microscope should be used for measurement. e) Unsheathed fan-shaped flat flexible cables shall be measured according to Figure 6. Half of the shortest distance between the two conductors shall be taken as the insulation thickness of the insulated core. In any case, the first measurement shall be made at the thinnest point of the insulation. If the insulation test piece includes a stamped mark indentation, the insulation thickness at that point shall not be used to calculate the average thickness. However, in any case, the insulation thickness at the stamped mark indentation shall comply with the minimum value specified in the relevant cable product standards. If the specified insulation thickness is 0.5mm or above, the reading shall be measured to two decimal places (in mm). If the specified insulation thickness is less than 0.5mm, the reading shall be measured to three decimal places, and the third digit shall be an estimate. 8.1.5 Evaluation of measurement results
The measurement results shall be evaluated in accordance with the test requirements in the relevant cable product standards. Conduct the machine During the mechanical properties test, the average value of the thickness of each test piece (see 9.1.4b1)) shall be calculated based on the 6 maximum values measured on the test piece.
8.2 Measurement of non-metallic sheath thickness
8.2.1 Overview
The measurement of sheath thickness can be performed as a separate test or as a step in other tests such as mechanical properties tests. This test method is also applicable to the measurement of other sheaths with specified thicknesses, such as isolation sheaths and outer sheaths. In all cases, the sampling method shall comply with the provisions of the relevant cable product standards. B.2.2 Measuring device
(8.1.2)
8.2.3 Sample preparation
Remove all components inside and outside the sheath (if any), and use an appropriate tool to remove the components. (A sharp blade such as a razor blade, etc.) Cut the slice along a plane perpendicular to the cable axis.
If there is an indentation with an embossed mark on the sheath, the thickness at that place will be thinner. Therefore, a section containing the mark should be taken from the test piece. B.2.4 Measurement steps
Place the test piece on the working surface of the measuring device with the cutting surface perpendicular to the optical axis. a) When the inside of the test piece is circular, 6 points should be measured radially according to Figure 1. b) If the inner circular surface of the test piece is essentially irregular or not smooth, 6 points should be measured radially at the thinnest part of the sheath according to Figure 7. e) When there are deep grooves caused by conductors on the inside of the test piece, radial measurements should be made at the bottom of each groove according to Figure 8. When the number of grooves exceeds 6, measurements should be made according to Figure 8. d) When the outer surface of the expanded sheath is irregular due to scraping tape or the shape of the auxiliary strip sheath,The measurement shall be made according to Figure 9. e) For flat flexible cables with sheath, the measurement shall be made according to Figure 10 in the direction roughly parallel to the minor axis of the cross section of each insulating core and on the major axis. However, no matter what, the measurement shall be made at the thinnest point. f) Flat cables with six cores or less with sheath shall be measured according to Figure 11: one is measured along the major axis of the cross section at both ends of the circle, and one is measured on the two sides of the flat surface, on the first and last insulating cores. If the thinnest thickness is not in the above-mentioned measurement values, the measurement of the thickness at the thinnest point and in the opposite direction shall be added. The above provisions also apply to the measurement of the sheath thickness of flat cables with more than six cores, but the measurement shall be made at the intermediate insulating cores or at one of the two insulating cores when the number of insulating cores is even. In any case, one measurement must be made at the thinnest point of the sheath. If the sheath sample includes a stamped mark indentation, the thickness at that point shall not be used to calculate the average thickness. However, in any case, the sheath thickness at the stamped mark indentation shall comply with the minimum value specified in the relevant cable product standards. The reading should be to two decimal places (in mm). 8.2.5 Evaluation of measurement results
GB/T2951.1-1997
The measurement results should be evaluated in accordance with the test requirements in the relevant cable product standards: When conducting mechanical property tests, the average thickness of each test piece 8 (9.2.4) should be calculated based on all the measured values measured on the test piece. 8.3 Measurement of external dimensions
8.3.1 Overview
The measurement of the outer diameter of the core insulation and the outer diameter of the sheath can be used as a separate test or as a step in other test processes. Unless a different or alternative method is specified in a special test procedure, the general measurement method is specified in the following 8.3.2. In all cases, the sampling method shall comply with the provisions of the relevant cable product standards. 8.3.2 Measurement steps
a) When the outer diameter of the cord and cable does not exceed 25tuti, use a micrometer, projector or similar screen to measure in two directions perpendicular to each other.
Routine tests allow the use of graduated micrometers or vernier calipers to measure the scene. The contact pressure should be minimized during measurement. b) When the outer diameter of the cord and cable exceeds 25mm, the circumference should be measured with a measuring tape, and then the diameter should be calculated. It can also be measured using a measuring tape that can read directly.
c) Flat cords and cables should be measured along the major and minor axes of the cross section using a micrometer, a projector or similar instrument. Unless otherwise specified in the relevant cable product standards; for sizes of 25mm and below, the readings should be rounded to two decimal places (in mm), and for sizes of 25 mm and above, the readings should be rounded to one decimal place. 8.3.3 Evaluation of measurement results
The measurement results should be evaluated in accordance with the test requirements in the relevant cable product standards. 9 Methods for measuring mechanical properties of insulation and sheath materials 9.1 Insulation materials
9.1.1 Overview
This method is used to determine the tensile strength and breaking elongation of cable insulation materials (excluding the semi-conductive layer) under the conditions of the cable as manufactured (i.e. without aging treatment), and if necessary, after one or more accelerated aging treatments specified in the relevant cable product standards. Air oven, air bomb and oxygen bomb. Aging steps refer to Chapter 8 of GB/T2951.2-1997. The test pieces to be aged should be taken from the section immediately behind the test pieces for the unaged test. The tensile tests of aged and unaged test pieces should be carried out continuously.
Note: If it is necessary to increase the reliability of the test, it is recommended that the same operator of the company use the same test method and the same machine in the same laboratory to test the aged and unaged test pieces.
9.1-2 Sampling
Cut a sample of sufficient length from each insulated wire core sample to be tested (or each insulation sample of the insulated wire core to be taken) to prepare at least 5 test pieces for mechanical properties test before aging and at least 5 test pieces for various aging tests. Note that the sampling length for preparing each test piece is required to be 100mm.
The insulated wire core of the fan-flat flexible wire should not be separated. Any sample with mechanical damage should not be used for testing. 9.1.3 Preparation of test pieces (skin treatment)
and) dumb test pieces
Use dumbbell test pieces as much as possible. Cut the insulated wire core axially, extract the conductor, and prepare dumbbell test pieces from the insulation sample. If there is a semi-conductive layer on the inner and outer sides of the insulation, it should be removed by mechanical means without using solvents. Each insulation sample should be cut into test strips of appropriate length and marked on the test strips to identify which sample it was taken from and its relative position on the sample.
The insulation test strip should be flattened or shaved so that the marking lines have parallel surfaces. Care should be taken to avoid overheating during grinding. For an example of a shaver, see Appendix A. For PE and PP insulation, only shaved but not ground can be used. After grinding or shaving, the thickness of the test strip should be not less than 0.6 mm and not more than GB/T 2951. 1 -- 1997
2.0 mm. If a thickness of 0.8 mm cannot be obtained, a minimum thickness of 0.6 mm is allowed. Then, from the prepared insulation test strip 1, a dumbbell test piece as shown in Figure 12 is punched out. If possible, two dumbbell test pieces should be punched out side by side. In order to improve the reliability of the test results, the following measures are recommended: The punch (bell-smashing knife) should be very sharp to reduce defects on the test piece. Place cardboard or other suitable gaskets between the test strip and the base plate. The gasket may be broken during the punching process, but it will not be completely cut off by the punch (dumbbell knife):
- Avoid burrs on both sides of the test piece.
For materials that may punch out dumbbell test pieces with burrs, the following methods can be used: 1) There should be a groove of 2.5mm wide and 2.5mm high at both ends of the punch (see Figure 14); 2) The two ends of the punched dumbbell test piece are still connected to the test strip prepared according to the requirements of 9.1.3a) (see Figure 15); 3) If the preparation in Appendix A is used, the excess 0.1~0.15mm thickness can be cut off to remove the burrs that may be caused by the dumbbell punch. After the above operation is completed, the two ends of the dumbbell test piece are cut off from the insulating test strip and the dumbbell test piece is taken out. When the diameter of the insulated wire core is too small to punch the test piece with the punch shown in Figure 12, the small punch shown in Figure 13 can be used to punch the test piece from the prepared test strip.
Before the tensile test, mark two marking lines in the center of each dumbbell specimen. The distance between them is: 20mm for large dumbbell specimens; 10mm for small dumbbell specimens.
It is allowed that the two ends of the dumbbell specimen are incomplete, as long as the break occurs between the marking lines. b) Tubular specimens
Tubular specimens are used only when the size of the insulated core cannot prepare dumbbell specimens. Cut the core specimen into small pieces of about 100mm long, extract the conductor, and remove all outer sheaths, taking care not to damage the insulation. Each tubular specimen is marked to identify which specimen it is taken from and its relative position on the specimen. The extraction of the conductor can be facilitated by using one or more of the following operating methods: 1) Pull the hard conductor,
2) Carefully roll the insulated core under a small mechanical force 3) If it is a stranded core or soft conductor, the center one or more conductors can be extracted first. After the conductor is extracted: remove the isolation layer (if any). If there are difficulties, any of the following methods may be used: 1. In the case of paper insulation, immerse in water; 2. In the case of polyamide insulation, immerse in alcohol, roll the insulation on a smooth surface. 3. Before the tensile test, mark two marks in the middle of each tubular test piece with a spacing of 20 mm1. If the insulation layer remains in the tubular test piece, the test piece will be found to be irregular when the sample is stretched during the tensile test. If the above situation occurs, the test result shall be invalid. c) Treatment of samples 4. Before the tensile test, all test pieces shall be stored at (23 ± 5) ° C for at least 3 hours. Avoid direct sunlight, but the storage temperature of thermoplastic insulation material parts shall be (23 ± 2). 5. In case of doubt, all materials or test strips shall be placed at (70 ± 2) for 24 hours before making strip test pieces (if no other treatment temperature is specified in the relevant cable product standards). 6. The treatment temperature shall not exceed the maximum operating temperature of the conductor. This process should be carried out before measuring the size of the test piece. 9.1.4 Measurement of cross-sectional area
a) Dumbbell test piece
The cross-sectional area of each test piece is the product of the width of the test piece and the minimum thickness measured. The width and thickness of the test piece should be measured as follows. Width
Choose three test pieces and measure their widths. Take the minimum value as the width of the dumbbell test piece of this group; GB/T 2951. 1-1997
If there is any doubt about the uniformity of the width, the width of the upper and lower sides of the three test pieces should be measured at three points respectively, and the average value of the measured values at the upper and lower measurement points should be calculated. The minimum value of the 9 average values of the three test pieces is taken as the width of the dumbbell test piece of this group. If there is still doubt. The width should be measured on each test piece F:.
Thickness.
The thickness of each test piece is the minimum value of the three measured values in the tensile area. Optical instruments or pointer thickness gauges should be used for measurement, and the contact pressure should not exceed 0.07N/mm2. The error in measuring the maximum thickness should not be greater than 0.01 mm, and the error in measuring the width should not be greater than (1.04 mm. In case of doubt and where technically feasible, an optical instrument should be used. Alternatively, a pointer-type thickness gauge with a contact pressure not greater than 0.02N/mm can be used.
Note: If the middle part of the dumbbell specimen is shaped, a pointer thickness gauge with a suitable arc measuring head can be used. h) Tubular specimen
Cut a specimen in the middle of the specimen and measure its cross-sectional area A (in mm) using one of the following measurement methods. If in doubt: the second method should be used 62)
h1) Calculate based on cross-sectional dimensions:
A=(D—)
Where: average insulation thickness, mm, measured according to Chapter 8 and rounded to two decimal places (see the last paragraph of 8.1.4) D——average outer diameter of tubular specimen, mm, measured according to 8.3.2 test method b) and rounded to two decimal places. b2) Calculate based on density, mass and length: A=axt
Where: m—mass name of the specimen, to three decimal places; L length, mm, to one decimal place:
d—-density, R/cm, measured on another specimen (not aged) of the mesh insulation specimen section according to Chapter 8 of GB/T2951.3.-1997, to three decimal places.
b3) Calculate based on volume and length:
Wherein, V is volume, mm\, to two decimal places; L is length, mm, to one decimal place.
The volume V can be measured by immersing the sample in alcohol. When immersing the sample in alcohol, care should be taken to avoid the formation of gas pools on the sample. c) For samples that need to be aged, the cross-sectional area should be measured before aging treatment. However, the test pieces where the insulation and conductor are aged together are excluded. 9.1.5 Aging treatment
Each group of tests requiring aging treatment should be carried out on 5 test pieces (see 9.1.2) under the aging conditions specified in the relevant cable product standards in accordance with Chapter 8 of GB/T2951.2-1997. 9.1.6 Sample pretreatment
Before the tensile test, all samples shall be stored at (23±5)℃ for at least 3h. For thermoplastic insulation samples, they shall be stored at (23±2)℃ for at least 3h.
9.1.7 Tensile test steps
U) Test temperature
The test shall be carried out at (23±5)℃. When there is doubt about thermoplastic insulation materials, the test shall be carried out at (23±2)℃. b) Spacing between chucks and moving speed
The chucks of the tensile testing machine can be either self-tightening chucks or non-tightening chucks. The total spacing between the grips is approximately:
For bell specimens as shown in Figure 13
For dumbbell specimens as shown in Figure 12
When tested with white-tight grips, tubular specimens are tested with non-self-tightening grips, tubular specimens GB/T2951.11997
85mm.
The grip movement speed should be (250±50)mm/min, except for PE and PP insulation. In case of doubt, the movement speed should be (25±5)mm/min.
For PE and PP insulation, or insulation containing these materials, the movement speed should be (25±5)mm/min. However, when conducting a test, a movement speed of (250±50)mm/min and less is allowed. ) Measurement
Measure and record the maximum tensile force during the test. At the same time, measure the distance between the two marking lines at the time of rupture on the same specimen. The test results of any test piece that breaks at the chuck shall be invalidated. In this case, at least 4 valid data are required to calculate the tensile strength and elongation at break, otherwise the test shall be repeated. 9.1.8 Method of expressing test results
Calculate the tensile strength and elongation at break according to the definitions of 7.3 and 7.4 respectively, and then determine the intermediate value of the test results. 9.2 Sheath material
9.2.1 Overview
This method measures the tensile strength and elongation at break of the cable sheath material under the conditions of the cable as manufactured, and if necessary, after one or more aging treatments specified in the relevant cable product standards. When the prepared test piece needs to be aged (according to Article 8.1.3 of GB/T2951.2-1997 or Chapter 10 of GB/T2951.5-1997), the test piece that needs to be aged should be taken close to the test piece that is not subjected to the aging test. The tensile test of the aged and technically aged test pieces shall be carried out continuously. NOTE: If necessary to improve the reliability of the test, the same operator shall be used to test the aged and unaged specimens in the same laboratory and on the same machine using the same test method: 9.2.2 Sampling Cut a sufficient length of each cable or cord sample or sheath sample of the cable to prepare at least 5 specimens for the pre-aging tensile test and the number of specimens required for the post-aging tensile test of the cable standard for the sheath material. Note that the length required for the preparation of each specimen is about 100 mm. Any specimen with mechanical damage shall not be used for the test. 9.2.3 Preparation and treatment of specimens The method for preparing specimens from sheath specimens is the same as the method for preparing insulation specimens specified in 9.1.3. When preparing the slit test specimen, cut the sheath along the cable axis and cut a narrow strip. All cable components in the narrow strip are removed. If there are ridges or embossings in the narrow strip, they should be ground or flattened. For PE and PP sheaths, only flattening is required. For PE sheaths, if the sheath is thicker and smoother on both sides, the dumbbell test piece does not need to be as thick as 2.0 mm. When preparing tubular test pieces, all cable components in the sheath, including insulating cores, fillers and inner sheaths, should be removed. For the treatment of test pieces, refer to 9.1.3c).
9.2.4 Measurement of cross-sectional area
The cross-sectional area of each sheath sample is measured in the same way as the measurement method for insulating samples specified in 9.1.4. However, the following modifications are made to tubular test pieces:
- The sheath thickness used in method b1) should be measured in accordance with the provisions of 8.2.4, and the outer diameter should be measured in accordance with the provisions of 8.3.2. - The density is measured on another test piece of the same sheath according to method b2). Note that method b2) is not applicable to multi-layer sheaths. 9.2.5 Aging treatment
Each test requiring aging treatment shall be carried out on 5 test pieces (see 9.2.2) under the aging conditions specified in the relevant cable product standards in accordance with the requirements of Chapter 8 of GB/T2951.2-1997. 9.2.6 Sample treatment
Perform in accordance with 9.1.6.
9.2.7 Tensile test steps
Perform in accordance with 9.1.7.
9.2.8 Test result indication
Perform in accordance with 9.1.8.
GB/T 2951.1—1997
Minimum thickness
Figure 1 Insulation and sheath thickness measurement (circular inner surface) Minimum thickness
Figure 2 Insulation thickness measurement (sector-shaped conductor)
Minimum thickness
Figure 3 Insulation thickness measurement (stranded conductor)
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GB/T 2951.1—1997
Figure 4 Insulation thickness measurement (stranded conductor)
Minimum thickness
Figure 5 Insulation thickness measurement (irregular outer surface) Minimum float
Figure 6 Insulation thickness measurement (sector-shaped two-core non-sheathed flexible cord) GB/T 2951. 1--1997
Minimum thickness
Figure 7 Sheath thickness measurement (irregular circular inner surface) Minimum thickness,
Figure 8 Sheath thickness measurement (non-circular inner surface) Minimum pregnancy-
Figure 9 Sheath thickness measurement (irregular outer surface) GB/T 2951. 1--1997
Minimum sequence
Figure 10 Sheath thickness measurement (flat belt sheathed two-core soft wire) Figure 11 Sheath thickness measurement (multi-core shoulder cable) Marking line
Figure 12 Sleeping bell test piece
Marking line
Figure 13 Small dumbbell test piece
Dimension unit: mm
Dimension unit: nmm
CB/T 2951. 1—1997
One end of the punch with groove
5Test piece punched by the punch with groove
Dimensions in mm02N/mm pointer-type thickness test,
Note: If the middle part of the dumbbell test piece is shaped, a pointer thickness gauge with a suitable arc measuring head can be used. h) Tubular test piece
Cut a test piece in the middle of the test piece, and then measure its cross-sectional area A (unit: mm) using one of the following measurement methods. In case of doubt: the second method should be used 62)
h1) Calculate according to the cross-sectional dimensions:
A=(D—)
Where: Average value of insulation thickness, mm, measured according to Chapter 8 and rounded to two decimal places (see the last paragraph of 8.1.4) D——Average value of the outer diameter of the tubular test piece, mm, measured according to the test method b) of 8.3.2 and rounded to two decimal places. b2) Calculate based on density, mass and length: A=axt
Where: m—mass name of the sample, to three decimal places; L—length, mm, to one decimal place:
d—degree, R/cm, measured on another sample (not aged) of the mesh insulation sample section according to Chapter 8 of GB/T2951.3.-1997, to three decimal places.
b3) Calculate based on volume and length:
Where: V——volume, mm\, to two decimal places; L—length, mm, to one decimal place.
The maximum volume V can be measured by immersing the sample in alcohol. When immersing the sample in alcohol, be careful to avoid forming a gas pool on the sample. c) For samples that need to be aged, the cross-sectional area should be measured before aging treatment. However, the test piece where the insulation strip and conductor are aged together is an exception. 9.1.5 Aging treatment
Each group of tests requiring aging treatment shall be carried out on 5 test pieces (see 9.1.2) under the aging conditions specified in the relevant cable product standards in accordance with Chapter 8 of GB/T2951.2-1997. 9.1.6 Sample pretreatment
Before the tensile test, all samples shall be stored at (23±5)℃ for at least 3h. For thermoplastic insulation samples, they shall be stored at (23±2)℃ for at least 3h.
9.1.7 Tensile test steps
U) Test temperature
The test shall be carried out at (23±5)℃. When there is doubt about thermoplastic insulation materials, the test shall be carried out at (23±2)℃. b) Spacing and moving speed between chucks
The chucks of the tensile testing machine can be either self-tightening chucks or non-tightening chucks. The total spacing between the grips is approximately:
For bell specimens as shown in Figure 13
For dumbbell specimens as shown in Figure 12
When tested with white-tight grips, tubular specimens are tested with non-self-tightening grips, tubular specimens GB/T2951.11997
85mm.
The grip movement speed should be (250±50)mm/min, except for PE and PP insulation. In case of doubt, the movement speed should be (25±5)mm/min.
For PE and PP insulation, or insulation containing these materials, the movement speed should be (25±5)mm/min. However, when conducting a test, a movement speed of (250±50)mm/min and less is allowed. ) Measurement
Measure and record the maximum tensile force during the test. At the same time, measure the distance between the two marking lines at the time of rupture on the same specimen. The test results of any test piece that breaks at the chuck shall be invalidated. In this case, at least 4 valid data are required to calculate the tensile strength and elongation at break, otherwise the test shall be repeated. 9.1.8 Method of expressing test results
Calculate the tensile strength and elongation at break according to the definitions of 7.3 and 7.4 respectively, and then determine the intermediate value of the test results. 9.2 Sheath material
9.2.1 Overview
This method measures the tensile strength and elongation at break of the cable sheath material under the conditions of the cable as manufactured, and if necessary, after one or more aging treatments specified in the relevant cable product standards. When the prepared test piece needs to be aged (according to Article 8.1.3 of GB/T2951.2-1997 or Chapter 10 of GB/T2951.5-1997), the test piece that needs to be aged should be taken close to the test piece that is not subjected to the aging test. The tensile test of the aged and technically aged test pieces shall be carried out continuously. NOTE: If necessary to improve the reliability of the test, the same operator shall be used to test the aged and unaged specimens in the same laboratory and on the same machine using the same test method: 9.2.2 Sampling Cut a sufficient length of each cable or cord sample or sheath sample of the cable to prepare at least 5 specimens for the pre-aging tensile test and the number of specimens required for the post-aging tensile test of the cable standard for the sheath material. Note that the length required for the preparation of each specimen is about 100 mm. Any specimen with mechanical damage shall not be used for the test. 9.2.3 Preparation and treatment of specimens The method for preparing specimens from sheath specimens is the same as the method for preparing insulation specimens specified in 9.1.3. When preparing the slit test specimen, cut the sheath along the cable axis and cut a narrow strip. All cable components in the narrow strip are removed. If there are ridges or embossings in the narrow strip, they should be ground or flattened. For PE and PP sheaths, only flattening is required. For PE sheaths, if the sheath is thicker and smoother on both sides, the dumbbell test piece does not need to be as thick as 2.0 mm. When preparing tubular test pieces, all cable components in the sheath, including insulating cores, fillers and inner sheaths, should be removed. For the treatment of test pieces, refer to 9.1.3c).
9.2.4 Measurement of cross-sectional area
The cross-sectional area of each sheath sample is measured in the same way as the measurement method for insulating samples specified in 9.1.4. However, the following modifications are made to tubular test pieces:
- The sheath thickness used in method b1) should be measured in accordance with the provisions of 8.2.4, and the outer diameter should be measured in accordance with the provisions of 8.3.2. - The density is measured on another test piece of the same sheath according to method b2). Note that method b2) is not applicable to multi-layer sheaths. 9.2.5 Aging treatment
Each test requiring aging treatment shall be carried out on 5 test pieces (see 9.2.2) under the aging conditions specified in the relevant cable product standards in accordance with the requirements of Chapter 8 of GB/T2951.2-1997. 9.2.6 Sample treatment
Perform in accordance with 9.1.6.
9.2.7 Tensile test steps
Perform in accordance with 9.1.7.
9.2.8 Test result indication
Perform in accordance with 9.1.8.
GB/T 2951.1—1997
Minimum thickness
Figure 1 Insulation and sheath thickness measurement (circular inner surface) Minimum thickness
Figure 2 Insulation thickness measurement (sector-shaped conductor)
Minimum thickness
Figure 3 Insulation thickness measurement (stranded conductor)
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GB/T 2951.1—1997
Figure 4 Insulation thickness measurement (stranded conductor)
Minimum thickness
Figure 5 Insulation thickness measurement (irregular outer surface) Minimum float
Figure 6 Insulation thickness measurement (sector-shaped two-core non-sheathed flexible cord) GB/T 2951. 1--1997
Minimum thickness
Figure 7 Sheath thickness measurement (irregular circular inner surface) Minimum thickness,
Figure 8 Sheath thickness measurement (non-circular inner surface) Minimum pregnancy-
Figure 9 Sheath thickness measurement (irregular outer surface) GB/T 2951. 1--1997
Minimum sequence
Figure 10 Sheath thickness measurement (flat belt sheathed two-core soft wire) Figure 11 Sheath thickness measurement (multi-core shoulder cable) Marking line
Figure 12 Sleeping bell test piece
Marking line
Figure 13 Small dumbbell test piece
Dimension unit: mm
Dimension unit: nmm
CB/T 2951. 1—1997
One end of the punch with groove
5Test piece punched by the punch with groove
Dimensions in mm02N/mm pointer-type thickness test,
Note: If the middle part of the dumbbell test piece is shaped, a pointer thickness gauge with a suitable arc measuring head can be used. h) Tubular test piece
Cut a test piece in the middle of the test piece, and then measure its cross-sectional area A (unit: mm) using one of the following measurement methods. In case of doubt: the second method should be used 62)
h1) Calculate according to the cross-sectional dimensions:
A=(D—)
Where: Average value of insulation thickness, mm, measured according to Chapter 8 and rounded to two decimal places (see the last paragraph of 8.1.4) D——Average value of the outer diameter of the tubular test piece, mm, measured according to the test method b) of 8.3.2 and rounded to two decimal places. b2) Calculate based on density, mass and length: A=axt
Where: m—mass name of the sample, to three decimal places; L—length, mm, to one decimal place:
d—degree, R/cm, measured on another sample (not aged) of the mesh insulation sample section according to Chapter 8 of GB/T2951.3.-1997, to three decimal places.
b3) Calculate based on volume and length:
Where: V——volume, mm\, to two decimal places; L—length, mm, to one decimal place.
The maximum volume V can be measured by immersing the sample in alcohol. When immersing the sample in alcohol, be careful to avoid forming a gas pool on the sample. c) For samples that need to be aged, the cross-sectional area should be measured before aging treatment. However, the test piece where the insulation strip and conductor are aged together is an exception. 9.1.5 Aging treatment
Each group of tests requiring aging treatment shall be carried out on 5 test pieces (see 9.1.2) under the aging conditions specified in the relevant cable product standards in accordance with Chapter 8 of GB/T2951.2-1997. 9.1.6 Sample pretreatment
Before the tensile test, all samples shall be stored at (23±5)℃ for at least 3h. For thermoplastic insulation samples, they shall be stored at (23±2)℃ for at least 3h.
9.1.7 Tensile test steps
U) Test temperature
The test shall be carried out at (23±5)℃. When there is doubt about thermoplastic insulation materials, the test shall be carried out at (23±2)℃. b) Spacing and moving speed between chucks
The chucks of the tensile testing machine can be either self-tightening chucks or non-tightening chucks. The total spacing between the grips is approximately:
For bell specimens as shown in Figure 13
For dumbbell specimens as shown in Figure 12
When tested with white-tight grips, tubular specimens are tested with non-self-tightening grips, tubular specimens GB/T2951.11997
85mm.
The grip movement speed should be (250±50)mm/min, except for PE and PP insulation. In case of doubt, the movement speed should be (25±5)mm/min.
For PE and PP insulation, or insulation containing these materials, the movement speed should be (25±5)mm/min. However, when conducting a test, a movement speed of (250±50)mm/min and less is allowed. ) Measurement
Measure and record the maximum tensile force during the test. At the same time, measure the distance between the two marking lines at the time of rupture on the same specimen. The test results of any test piece that breaks at the chuck shall be invalidated. In this case, at least 4 valid data are required to calculate the tensile strength and elongation at break, otherwise the test shall be repeated. 9.1.8 Method of expressing test results
Calculate the tensile strength and elongation at break according to the definitions of 7.3 and 7.4 respectively, and then determine the intermediate value of the test results. 9.2 Sheath material
9.2.1 Overview
This method measures the tensile strength and elongation at break of the cable sheath material under the conditions of the cable as manufactured, and if necessary, after one or more aging treatments specified in the relevant cable product standards. When the prepared test piece needs to be aged (according to Article 8.1.3 of GB/T2951.2-1997 or Chapter 10 of GB/T2951.5-1997), the test piece that needs to be aged should be taken close to the test piece that is not subjected to the aging test. The tensile test of the aged and technically aged test pieces shall be carried out continuously. NOTE: If necessary to improve the reliability of the test, the same operator shall be used to test the aged and unaged specimens in the same laboratory and on the same machine using the same test method: 9.2.2 Sampling Cut a sufficient length of each cable or cord sample or sheath sample of the cable to prepare at least 5 specimens for the pre-aging tensile test and the number of specimens required for the post-aging tensile test of the cable standard for the sheath material. Note that the length required for the preparation of each specimen is about 100 mm. Any specimen with mechanical damage shall not be used for the test. 9.2.3 Preparation and treatment of specimens The method for preparing specimens from sheath specimens is the same as the method for preparing insulation specimens specified in 9.1.3. When preparing the slit test specimen, cut the sheath along the cable axis and cut a narrow strip. All cable components in the narrow strip are removed. If there are ridges or embossings in the narrow strip, they should be ground or flattened. For PE and PP sheaths, only flattening is required. For PE sheaths, if the sheath is thicker and smoother on both sides, the dumbbell test piece does not need to be as thick as 2.0 mm. When preparing tubular test pieces, all cable components in the sheath, including insulating cores, fillers and inner sheaths, should be removed. For the treatment of test pieces, refer to 9.1.3c).
9.2.4 Measurement of cross-sectional area
The cross-sectional area of each sheath sample is measured in the same way as the measurement method for insulating samples specified in 9.1.4. However, the following modifications are made to tubular test pieces:
- The sheath thickness used in method b1) should be measured in accordance with the provisions of 8.2.4, and the outer diameter should be measured in accordance with the provisions of 8.3.2. - The density is measured on another test piece of the same sheath according to method b2). Note that method b2) is not applicable to multi-layer sheaths. 9.2.5 Aging treatment
Each test requiring aging treatment shall be carried out on 5 test pieces (see 9.2.2) under the aging conditions specified in the relevant cable product standards in accordance with the requirements of Chapter 8 of GB/T2951.2-1997. 9.2.6 Sample treatment
Perform in accordance with 9.1.6.
9.2.7 Tensile test steps
Perform in accordance with 9.1.7.
9.2.8 Test result indication
Perform in accordance with 9.1.8.
GB/T 2951.1—1997
Minimum thickness
Figure 1 Insulation and sheath thickness measurement (circular inner surface) Minimum thickness
Figure 2 Insulation thickness measurement (sector-shaped conductor)
Minimum thickness
Figure 3 Insulation thickness measurement (stranded conductor)
Valve
GB/T 2951.1—1997
Figure 4 Insulation thickness measurement (stranded conductor)
Minimum thickness
Figure 5 Insulation thickness measurement (irregular outer surface) Minimum float
Figure 6 Insulation thickness measurement (sector-shaped two-core non-sheathed flexible cord) GB/T 2951. 1--1997
Minimum thickness
Figure 7 Sheath thickness measurement (irregular circular inner surface) Minimum thickness,
Figure 8 Sheath thickness measurement (non-circular inner surface) Minimum pregnancy-
Figure 9 Sheath thickness measurement (irregular outer surface) GB/T 2951. 1--1997
Minimum sequence
Figure 10 Sheath thickness measurement (flat belt sheathed two-core soft wire) Figure 11 Sheath thickness measurement (multi-core shoulder cable) Marking line
Figure 12 Sleeping bell test piece
Marking line
Figure 13 Small dumbbell test piece
Dimension unit: mm
Dimension unit: nmm
CB/T 2951. 1—1997
One end of the punch with groove
5Test piece punched by the punch with groove
Dimensions in mm-1997 Chapter 8 Measure on another sample of the (unaged) section of the mesh insulation sample, to three decimal places.
b3) Calculate based on volume and length:
Where, V——volume, mm\, to two decimal places; L—length, mm, to one decimal place.
The maximum volume V can be measured by immersing the sample in alcohol. When immersing the sample in alcohol, care should be taken to avoid the formation of gas pools on the sample. c) For samples that need to be aged, the cross-sectional area should be measured before aging treatment. However, the test pieces where the insulation strip and conductor are aged together are excluded. 9.1.5 Aging treatment
Each group of tests requiring aging treatment should be carried out on 5 test pieces (see 9.1.2) under the aging conditions specified in the relevant cable product standards in accordance with Chapter 8 of GB/T2951.2-1997. 9.1.6 Sample pretreatment
Before the tensile test, all samples shall be stored at (23±5)℃ for at least 3h. For thermoplastic insulation samples, they shall be stored at (23±2)℃ for at least 3h.
9.1.7 Tensile test steps
U) Test temperature
The test shall be carried out at (23±5)℃. When there is doubt about thermoplastic insulation materials, the test shall be carried out at (23±2)℃. b) Spacing between chucks and moving speed
The chucks of the tensile testing machine can be either self-tightening chucks or non-tightening chucks. The total spacing between the grips is approximately:
For bell specimens as shown in Figure 13
For dumbbell specimens as shown in Figure 12
When tested with white-tight grips, tubular specimens are tested with non-self-tightening grips, tubular specimens GB/T2951.11997
85mm.
The grip movement speed should be (250±50)mm/min, except for PE and PP insulation. In case of doubt, the movement speed should be (25±5)mm/min.
For PE and PP insulation, or insulation containing these materials, the movement speed should be (25±5)mm/min. However, when conducting a test, a movement speed of (250±50)mm/min and less is allowed. ) Measurement
Measure and record the maximum tensile force during the test. At the same time, measure the distance between the two marking lines at the time of rupture on the same specimen. The test results of any test piece that breaks at the chuck shall be invalidated. In this case, at least 4 valid data are required to calculate the tensile strength and elongation at break, otherwise the test shall be repeated. 9.1.8 Method of expressing test results
Calculate the tensile strength and elongation at break according to the definitions of 7.3 and 7.4 respectively, and then determine the intermediate value of the test results. 9.2 Sheath material
9.2.1 Overview
This method measures the tensile strength and elongation at break of the cable sheath material under the conditions of the cable as manufactured, and if necessary, after one or more aging treatments specified in the relevant cable product standards. When the prepared test piece needs to be aged (according to Article 8.1.3 of GB/T2951.2-1997 or Chapter 10 of GB/T2951.5-1997), the test piece that needs to be aged should be taken close to the test piece that is not subjected to the aging test. The tensile test of the aged and technically aged test pieces shall be carried out continuously. NOTE: If necessary to improve the reliability of the test, the same operator shall be used to test the aged and unaged specimens in the same laboratory and on the same machine using the same test method: 9.2.2 Sampling Cut a sufficient length of each cable or cord sample or sheath sample of the cable to prepare at least 5 specimens for the pre-aging tensile test and the number of specimens required for the post-aging tensile test of the cable standard for the sheath material. Note that the length required for the preparation of each specimen is about 100 mm. Any specimen with mechanical damage shall not be used for the test. 9.2.3 Preparation and treatment of specimens The method for preparing specimens from sheath specimens is the same as the method for preparing insulation specimens specified in 9.1.3. When preparing the slit test specimen, cut the sheath along the cable axis and cut a narrow strip. All cable components in the narrow strip are removed. If there are ridges or embossings in the narrow strip, they should be ground or flattened. For PE and PP sheaths, only flattening is required. For PE sheaths, if the sheath is thicker and smoother on both sides, the dumbbell test piece does not need to be as thick as 2.0 mm. When preparing tubular test pieces, all cable components in the sheath, including insulating cores, fillers and inner sheaths, should be removed. For the treatment of test pieces, refer to 9.1.3c).
9.2.4 Measurement of cross-sectional area
The cross-sectional area of each sheath sample is measured in the same way as the measurement method for insulating samples specified in 9.1.4. However, the following modifications are made to tubular test pieces:
- The sheath thickness used in method b1) should be measured in accordance with the provisions of 8.2.4, and the outer diameter should be measured in accordance with the provisions of 8.3.2. - The density is measured on another test piece of the same sheath according to method b2). Note that method b2) is not applicable to multi-layer sheaths. 9.2.5 Aging treatment
Each test requiring aging treatment shall be carried out on 5 test pieces (see 9.2.2) under the aging conditions specified in the relevant cable product standards in accordance with the requirements of Chapter 8 of GB/T2951.2-1997. 9.2.6 Sample treatment
Perform in accordance with 9.1.6.
9.2.7 Tensile test steps
Perform in accordance with 9.1.7.
9.2.8 Test result indication
Perform in accordance with 9.1.8.
GB/T 2951.1—1997
Minimum thickness
Figure 1 Insulation and sheath thickness measurement (circular inner surface) Minimum thickness
Figure 2 Insulation thickness measurement (sector-shaped conductor)
Minimum thickness
Figure 3 Insulation thickness measurement (stranded conductor)
Valve
GB/T 2951.1—1997
Figure 4 Insulation thickness measurement (stranded conductor)
Minimum thickness
Figure 5 Insulation thickness measurement (irregular outer surface) Minimum float
Figure 6 Insulation thickness measurement (sector-shaped two-core non-sheathed flexible cord) GB/T 2951. 1--1997
Minimum thickness
Figure 7 Sheath thickness measurement (irregular circular inner surface) Minimum thickness,
Figure 8 Sheath thickness measurement (non-circular inner surface) Minimum pregnancy-
Figure 9 Sheath thickness measurement (irregular outer surface) GB/T 2951. 1--1997
Minimum sequence
Figure 10 Sheath thickness measurement (flat belt sheathed two-core soft wire) Figure 11 Sheath thickness measurement (multi-core shoulder cable) Marking line
Figure 12 Sleeping bell test piece
Marking line
Figure 13 Small dumbbell test piece
Dimension unit: mm
Dimension unit: nmm
CB/T 2951. 1—1997
One end of the punch with groove
5Test piece punched by the punch with groove
Dimensions in mm-1997 Chapter 8 Measure on another sample of the (unaged) section of the mesh insulation sample, to three decimal places.
b3) Calculate based on volume and length:
Where, V——volume, mm\, to two decimal places; L—length, mm, to one decimal place.
The maximum volume V can be measured by immersing the sample in alcohol. When immersing the sample in alcohol, care should be taken to avoid the formation of gas pools on the sample. c) For samples that need to be aged, the cross-sectional area should be measured before aging treatment. However, the test pieces where the insulation strip and conductor are aged together are excluded. 9.1.5 Aging treatment
Each group of tests requiring aging treatment should be carried out on 5 test pieces (see 9.1.2) under the aging conditions specified in the relevant cable product standards in accordance with Chapter 8 of GB/T2951.2-1997. 9.1.6 Sample pretreatment
Before the tensile test, all samples shall be stored at (23±5)℃ for at least 3h. For thermoplastic insulation samples, they shall be stored at (23±2)℃ for at least 3h.
9.1.7 Tensile test steps
U) Test temperature
The test shall be carried out at (23±5)℃. When there is doubt about thermoplastic insulation materials, the test shall be carried out at (23±2)℃. b) Spacing between chucks and moving speed
The chucks of the tensile testing machine can be either self-tightening chucks or non-tightening chucks. The total spacing between the grips is approximately:
For bell specimens as shown in Figure 13
For dumbbell specimens as shown in Figure 12
When tested with white-tight grips, tubular specimens are tested with non-self-tightening grips, tubular specimens GB/T2951.11997
85mm.
The grip movement speed should be (250±50)mm/min, except for PE and PP insulation. In case of doubt, the movement speed should be (25±5)mm/min.
For PE and PP insulation, or insulation containing these materials, the movement speed should be (25±5)mm/min. However, when conducting a test, a movement speed of (250±50)mm/min and less is allowed. ) Measurement
Measure and record the maximum tensile force during the test. At the same time, measure the distance between the two marking lines at the time of rupture on the same specimen. The test results of any test piece that breaks at the chuck shall be invalidated. In this case, at least 4 valid data are required to calculate the tensile strength and elongation at break, otherwise the test shall be repeated. 9.1.8 Method of expressing test results
Calculate the tensile strength and elongation at break according to the definitions of 7.3 and 7.4 respectively, and then determine the intermediate value of the test results. 9.2 Sheath material
9.2.1 Overview
This method measures the tensile strength and elongation at break of the cable sheath material under the conditions of the cable as manufactured, and if necessary, after one or more aging treatments specified in the relevant cable product standards. When the prepared test piece needs to be aged (according to Article 8.1.3 of GB/T2951.2-1997 or Chapter 10 of GB/T2951.5-1997), the test piece that needs to be aged should be taken close to the test piece that is not subjected to the aging test. The tensile test of the aged and technically aged test pieces shall be carried out continuously. NOTE: If necessary to improve the reliability of the test, the same operator shall be used to test the aged and unaged specimens in the same laboratory and on the same machine using the same test method: 9.2.2 Sampling Cut a sufficient length of each cable or cord sample or sheath sample of the cable to prepare at least 5 specimens for the pre-aging tensile test and the number of specimens required for the post-aging tensile test of the cable standard for the sheath material. Note that the length required for the preparation of each specimen is about 100 mm. Any specimen with mechanical damage shall not be used for the test. 9.2.3 Preparation and treatment of specimens The method for preparing specimens from sheath specimens is the same as the method for preparing insulation specimens specified in 9.1.3. When preparing the slit test specimen, cut the sheath along the cable axis and cut a narrow strip. All cable components in the narrow strip are removed. If there are ridges or embossings in the narrow strip, they should be ground or flattened. For PE and PP sheaths, only flattening is required. For PE sheaths, if the sheath is thicker and smoother on both sides, the dumbbell test piece does not need to be as thick as 2.0 mm. When preparing tubular test pieces, all cable components in the sheath, including insulating cores, fillers and inner sheaths, should be removed. For the treatment of test pieces, refer to 9.1.3c).
9.2.4 Measurement of cross-sectional area
The cross-sectional area of each sheath sample is measured in the same way as the measurement method for insulating samples specified in 9.1.4. However, the following modifications are made to tubular test pieces:
- The sheath thickness used in method b1) should be measured in accordance with the provisions of 8.2.4, and the outer diameter should be measured in accordance with the provisions of 8.3.2. - The density is measured on another test piece of the same sheath according to method b2). Note that method b2) is not applicable to multi-layer sheaths. 9.2.5 Aging treatment
Each test requiring aging treatment shall be carried out on 5 test pieces (see 9.2.2) under the aging conditions specified in the relevant cable product standards in accordance with the requirements of Chapter 8 of GB/T2951.2-1997. 9.2.6 Sample treatment
Perform in accordance with 9.1.6.
9.2.7 Tensile test steps
Perform in accordance with 9.1.7.
9.2.8 Test result presentation
Perform in accordance with 9.1.8.
GB/T 2951.1—1997
Minimum thickness
Figure 1 Insulation and sheath thickness measurement (circular inner surface) Minimum thickness
Figure 2 Insulation thickness measurement (sector-shaped conductor)
Minimum thickness
Figure 3 Insulation thickness measurement (stranded conductor)
Valve
GB/T 2951.1—1997
Figure 4 Insulation thickness measurement (stranded conductor)
Minimum thickness
Figure 5 Insulation thickness measurement (irregular outer surface) Minimum float
Figure 6 Insulation thickness measurement (sector-shaped two-core non-sheathed flexible cord) GB/T 2951. 1--1997
Minimum thickness
Figure 7 Sheath thickness measurement (irregular circular inner surface) Minimum thickness,
Figure 8 Sheath thickness measurement (non-circular inner surface) Minimum pregnancy-
Figure 9 Sheath thickness measurement (irregular outer surface) GB/T 2951. 1--1997
Minimum sequence
Figure 10 Sheath thickness measurement (flat belt sheathed two-core soft wire) Figure 11 Sheath thickness measurement (multi-core shoulder cable) Marking line
Figure 12 Sleeping bell test piece
Marking line
Figure 13 Small dumbbell test piece
Dimension unit: mm
Dimension unit: nmm
CB/T 2951. 1—1997
One end of the punch with groove
5Test piece punched by the punch with groove
Dimensions in mm11997
85mm.
The speed of movement of the chuck shall be (250±50)mm/min, except for PE and PP insulation. In case of doubt, the speed of movement shall be (25±5)mm/min.
PE and PP insulation, or insulation containing these materials, shall be moved at a speed of (25±5)mm/min. However, when conducting the test, a speed of movement of (250±50)mm/min and below is permitted. ) Measurement
Measure and record the maximum tensile force during the test. At the same time, measure the distance between the two marking lines at the time of fracture on the same specimen. The test results of any specimen that breaks at the chuck shall be invalid. In this case, at least 4 valid data are required to calculate the tensile strength and elongation at break, otherwise the test shall be repeated. 9.1.8 Method of expressing test results
Calculate the tensile strength and elongation at break according to the definitions in 7.3 and 7.4 respectively, and then determine the median value of the test results. 9.2 Sheath material
9.2.1 Overview bZxz.net
This method measures the tensile strength and elongation at break of cable sheath materials under the conditions of the cable as manufactured, and if necessary, after one or more aging treatments specified in the relevant cable product standards. When the prepared test piece needs to be aged (according to Article 8.1.3 of GB/T2951.2-1997 or Chapter 10 of GB/T2951.5-1997), the test piece to be aged should be placed close to the test piece not to be aged. The tensile test of the aged and technically aged test pieces should be carried out continuously. NOTE: If necessary to improve the reliability of the test, the same operator shall be used to test the aged and unaged specimens in the same laboratory and on the same machine using the same test method: 9.2.2 Sampling Cut a sufficient length of each cable or cord sample or sheath sample of the cable to prepare at least 5 specimens for the pre-aging tensile test and the number of specimens required for the post-aging tensile test of the cable standard for the sheath material. Note that the length required for the preparation of each specimen is about 100 mm. Any specimen with mechanical damage shall not be used for the test. 9.2.3 Preparation and treatment of specimens The method for preparing specimens from sheath specimens is the same as the method for preparing insulation specimens specified in 9.1.3. When preparing the spit test specimen, cut the sheath along the cable axis and cut a narrow strip. All cable components in the narrow strip are removed. If there are ridges or embossings in the narrow strip, they should be ground or flattened. For PE and PP sheaths, only flattening is required. For PE sheaths, if the sheath is thicker and smoother on both sides, the dumbbell test piece does not need to be as thick as 2.0 mm. When preparing tubular test pieces, all cable components in the sheath, including insulating cores, fillers and inner sheaths, should be removed. For the treatment of test pieces, refer to 9.1.3c).
9.2.4 Measurement of cross-sectional area
The cross-sectional area of each sheath sample is measured in the same way as the measurement method for insulating samples specified in 9.1.4. However, the following modifications are made to tubular test pieces:
- The sheath thickness used in method b1) should be measured in accordance with the provisions of 8.2.4, and the outer diameter should be measured in accordance with the provisions of 8.3.2. - The density is measured on another test piece of the same sheath according to method b2). Note that method b2) is not applicable to multi-layer sheaths. 9.2.5 Aging treatment
Each test requiring aging treatment shall be carried out on 5 test pieces (see 9.2.2) under the aging conditions specified in the relevant cable product standards in accordance with the requirements of Chapter 8 of GB/T2951.2-1997. 9.2.6 Sample treatment
Perform in accordance with 9.1.6.
9.2.7 Tensile test steps
Perform in accordance with 9.1.7.
9.2.8 Test result indication
Perform in accordance with 9.1.8.
GB/T 2951.1—1997
Minimum thickness
Figure 1 Insulation and sheath thickness measurement (circular inner surface) Minimum thickness
Figure 2 Insulation thickness measurement (sector-shaped conductor)
Minimum thickness
Figure 3 Insulation thickness measurement (stranded conductor)
Valve
GB/T 2951.1—1997
Figure 4 Insulation thickness measurement (stranded conductor)
Minimum thickness
Figure 5 Insulation thickness measurement (irregular outer surface) Minimum float
Figure 6 Insulation thickness measurement (sector-shaped two-core non-sheathed flexible cord) GB/T 2951. 1--1997
Minimum thickness
Figure 7 Sheath thickness measurement (irregular circular inner surface) Minimum thickness,
Figure 8 Sheath thickness measurement (non-circular inner surface) Minimum pregnan
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