GB/T 7424.21-2021Optical fibre cable generic specification - Part 21: Basic optical cable test procedures - Mechanical test methods (English PDF)

7.4 in.2008);

---E4 modified the requirements of punch shape (see 6.3, 8.3 of the.2008 edition);

--- Deleted the stability of the peel force of the E5 cabled fiber and moved to GB/T 7424.23 (see Chapter 9 of the.2008 edition);

--- E6 deleted the repeated bending test of the optical cable in Figure 9 (see 10.3 of the.2008 edition);

--- E6 adds the requirement that the bending radius should not be greater than 20 times the diameter of the optical cable or the minimum mandrel radius (see 7.3);

--- E6 added "The mandrel with radius R should be rotated when bending" (see 7.3);

--- E7 added "Table 1 Typical Test Maximum Torsion Length" (see 8.4);

--- E7 added "or 90° (torsion length is 50% of Table 1)" (see 8.4);

--- E7 deleted "Tension imposed by Table 1" (see 11.4 of the.2008 edition);

---E8 added the description "This is a special test for special optical cables, such as elevator optical cables or similar optical cables" (see 9.1);

---E8 has increased the diameter requirements of pulley A and pulley B, and the requirements for the distance between each other (see 9.3);

--- E10 has added the calculation formula (1) of the equivalent ring diameter (see 10.4);

---E11 has added the double helix winding method in the curved E11A winding (see 11.4.1);

---E11 added "Figure 14 bending test device" (see 11.3);

--- Deleted "E12 cut-through resistance" (see Chapter 15 of the.2008 edition);

---E13 deletes the requirements of No. 4 or No. 7 bullets [see the.2008 edition of 16.3.2c), 16.4.2d)];

--- Modify the name of E17, from "rigid" to "bending rigid" (see Chapter 13, Chapter 17 of the.2008 edition);

---E17 has added a description of the test characteristics (see 13.1, 17.1 in the.2008 edition);

---E17 has added the test name, E17A is three-point bending, E17B is cantilever bending, and E17C is C-shaped bending (see 13.3,

13.4, 13.5);

--- In E17, the figure "Example of test results of applied force and displacement" in E17A is modified, and the transition zone between elastic and inelastic is given

(See Figure 19 in Chapter 13, Figure 21 in Chapter 17 of the.2008 edition);

---E17 has added the "definition of spacing factor" (see 13.5.3);

---Modified the name of E18, from "bending under tension (over pulley test)" to "bending under tension and over pulley test" (see

Chapter 14, Chapter 18 of the.2008 edition);

---Modified the name of E18A for bending under tension (see 14.1, 18.1 of the.2008 edition);

---Modified the name of E18B to the pulley test (mainly applicable to OPGW, OPPC, ADSS, OPAC optical cable) (see 14.2,

18.1 of the.2008 edition);

--- E18 has added the requirement that "the distance between point A and point B should be at least three times the pitch length" (see 14.1.2, 14.2.2);

--- E18B has added three pulleys "arranged in a straight line" (see procedure 2 in 14.2.3);

---E19 has added a regulation of 107 vibrations (see 15.4);

--- Increased the pull-out force of the E21 plug-in cord optical cable sheath (see Chapter 17);

--- Increased the compression displacement of the coated optical fiber in the E22 patch cord optical cable (see Chapter 18);

---Added E23 microtubule pipeline verification test (see Chapter 19);

---Added the installation test of the optical cable in the E24 microtube (see Chapter 20);

---Added E25 tear rope function test (see Chapter 21);

---Added E26 dancing (see Chapter 22);

---Added E27 indoor simulation installation test (see Chapter 23);

---Added the mechanical reliability test of E28 optical cable and optical fiber (see Chapter 24);

---Added the optical unit pumping test during E29 jumper (see Chapter 25);

--- Increased the friction coefficient between E30 optical cables (drum method) (see Chapter 26);

---Added E31 microtube clear space test (under consideration) (see Chapter 27);

---Increase the creep under E32 alternating tension (applicable to ADSS optical cable) (see Chapter 28);

--- Increased the performance of multiple coiling and unwinding of E33 optical cable (see Chapter 29);

--- Increased the coefficient of dynamic friction between E34 optical cables (plate method) (see Chapter 30).

This part uses the redrafting method to modify and adopt IEC 60794-1-21.2020 ``Optical Cable Part 1-21.General Specification Optical Cable Basic Test

Test Method Mechanical Performance Test Method".

Compared with IEC 60794-1-21.2020, this part has many structural adjustments. Appendix A lists this part and IEC 60794-

1-21.2020 chapter number comparison list.

Compared with IEC 60794-1-21.2020, this part has technical differences. The corresponding technical differences and their reasons are given in Appendix B

List.

This section also made the following editorial changes.

--- Modify the standard name to "General Specification for Optical Cables Part 21.Basic Test Methods for Optical Cables, Mechanical Performance Test Methods";

---E1 equipment 3.3.b) added "Note. When the test site permits, the number of pulleys should be reduced as much as possible to make the optical cable close to

Actual straight laying state";

---E6's 7.3 equipment adds a note about the friction between the optical cable and the mandrel;

---E7's 8.4 program adds a note about the description of the twisted length;

---E32's 28.1 purpose added note 2 of the difference of different methods;

---Informative appendix C, typical test curves and analysis of tensile strain and load of optical fibers and cables has been added.

3.1 Purpose

This test is suitable for testing the attenuation of the optical cable under test, the elongation strain of the optical fiber, and/or the strain of the optical cable under a specific tensile force.

As a function of the load, this load may occur during installation or operation. The intent of this test is non-destructive.

3.2 Specimen

Unless otherwise specified in the relevant specifications, the tested length is the sum of the length of the optical cable between the entry point of two chucks and the circumference of a chuck.

The length is not less than 50m. For optical cables that require special anchoring (such as OPGW, ADSS, thick steel wire armored optical cables, etc.), the tested length is not small

At 25m.

Excessively short length specimens in the tensile test will affect the measurement accuracy. The length indicated above is the minimum length given for this test.

The total length of the sample should be greater than the length of the test, in order to clamp and connect to the measuring equipment.

3.3 Equipment

The test equipment is shown in Figure 1 and Figure 2.Equipment includes.

a) An attenuation measuring device for measuring attenuation changes (see GB/T 15972.40), and an optical fiber elongation strain measuring device (see