What tests are needed for wires and cables

1. Electrical performance test

Mainly there are conductor DC resistance, insulation resistance, product voltage test and insulated wire voltage test, each of which is very important. The conductor resistance directly reflects the electrical transmission function of the cable, and directly affects the temperature, life span, voltage drop and operational safety of the cable during live operation. It mainly looks at the information and cross-sectional area of the wire and cable. If the conductor data is not good or the cross-sectional area is severely insufficient, the conductor DC resistance will severely exceed the standard. When this kind of wire and cable is laid in the line, it will increase the loss when the current passes through the line, causing the cable conductor to heat itself, causing the insulation of the covered conductor to age and crack, causing the power supply line to leak, short circuit, and even cause fire, endangering personal and industrial safety. This standard has strict rules on the DC resistance value of different standard cable conductors, which shall not be greater than the value of this standard rule.

2. Mechanical function test

The cable factory reminds us to study the tensile strength and elongation of insulation and sheath plastic materials before and after aging, as well as bending test, bending test, load core cracking test, insulation core tearing test, static bending test, etc. The tensile strength before and after aging and the elongation at break before and after aging are important and fundamental guidelines for cable insulation and sheath data, and are required to be used as wire and cable insulation and sheath data. They have satisfactory tensile strength, are not easy to crack, and have a certain degree of flexibility. Aging refers to the ability of insulation and sheath data to maintain their original functions under high temperature conditions. Aging should not severely affect the tensile strength and elongation of the data, which will directly affect the service life of the wire and cable. If the tensile strength and elongation at break are unqualified, the sheath or insulator will easily crack during the construction and installation of the cable. Perhaps the sheath and insulation of the cable used in light and thermal environments will become brittle and cracked, leading to exposure Of live conductors and risk of electric shock.

3. Insulation and sheath data function experiment

Including thermal weight loss, thermal shock, high temperature pressure, low temperature bending, low temperature stretching, low temperature impact, flame retardant functions, etc. These are all to study the insulation and sheathing functions of plastic materials. For example, the thermogravimetric test is to detect the degradation and volatilization degree of the data after aging at 80℃ for 7 days; the thermal shock test whether there are cracks on the insulation surface after special winding at 150℃ for 1h; the high temperature pressure test insulation data after high temperature and cooling; all low temperature experiments Generally refers to the change of its mechanical properties at -15°C. It is to test whether the wire and cable data becomes brittle, cracked or broken in a low temperature environment.

4. Mark inspection

The standard requires that the wire and cable packaging should be accompanied by a label or logo, indicating the product model, standard, standard number, manufacturer name and place of origin. The standard includes rated voltage, number of cores, and nominal conductor cross-section, etc. The appearance of the cable shall be printed with continuous marks of the manufacturer's name, product type and rated voltage. The mark distance is ≤200mm (insulation appearance) or ≤500mm (sheath appearance), and the content of the mark should be intact, clear and scratch-resistant. This requirement makes it easy for users to understand the types, standards and voltage levels of wires and cables to prevent laying errors. In addition, with regard to insulated cores, especially the yellow/green two-color cores commonly used in electrical product power cords, the colors recommended by the standard should be preferred. This special two-color wire is dedicated to grounding. The yellow/green matching code also has the following rules: For each insulated core with a length of 15mm, one color should cover at least 30% and not more than 70% of the insulated core, and the other color should cover the insulated core.

5. View of structure size

Including insulation and sheath thickness, overall dimensions, etc. The thickness of the insulation and sheath has an important effect on how much voltage the cable can withstand and its mechanical function. Therefore, with regard to wires and cables of different standards, the standards have strict rules on thickness, which should not be lower than the rule value of the national standard. If the insulation thickness of the wire and cable is too thin, it will severely affect the safety of the cable, and cause the exposed wires to cause cable breakdown, leakage and other safety hazards. Of course, the thicker the better, it should not affect the device. Therefore, the standard sets another size requirement to limit this.