Author: Noyafa–Cable Tester Manufacturer
What are the general inspection points for cables? 1. Measurement of wire DC resistance: For wires and cables, the conductor part is the most important part. The conductive core of the wire and cable mainly transmits electrical energy or electrical signals. What are the general inspection points for conductors and cables? 1. Measurement of wire DC resistance: For wires and cables, the conductor part is the most important part.
The conductive core of the wire and cable mainly transmits electrical energy or electrical signals. The resistance of the wire is the main indicator of its electrical performance. Now the standard stipulates: to detect whether the DC resistance or resistivity of the wire core exceeds the value specified in the standard. The main purpose of this inspection is to find some defects in the production process: such as wire breakage or part of the single wire breakage; wire cross-section does not meet the standard; product length is incorrect, etc.
In addition, for power cables, this test can not only detect the condition of the conductor, but also detect whether the conductor has an impact on the allowable current carrying capacity in the operation of the wire and cable products. 2. Test of insulation resistance: Insulation resistance is an important indicator reflecting the insulation characteristics of wire and cable products. It is closely related to the electrical strength of the product, dielectric loss, and the gradual deterioration of insulation materials under working conditions. Determination of insulation resistance can find defects in the process: such as the insulation is dry and impervious or the sheath is damaged and damp; the insulation is polluted and mixed with conductive impurities; the insulation layer is cracked due to various reasons, etc.
For communication cables, if the insulation resistance between wires is too low, it will also increase loop attenuation, crosstalk between loops, and long-distance power supply leakage on the conductive core. Therefore, the insulation resistance should be higher than the specified value. In the operation of wires and cables, it is often necessary to detect insulation resistance and leakage current as the main basis for continued safe operation. 3. Measurement of capacitance and loss factor: When AC voltage is applied to the cable, current flows. When the amplitude and frequency of the voltage are constant, the magnitude of the capacitor current is proportional to the capacitance (Cx) of the cable.
For ultra-high voltage cables, the current of this capacitor may reach a value comparable to the rated current, which becomes an important factor limiting the cable capacity and transmission distance. Therefore, the capacitance of the cable is also one of the main electrical performance parameters of the cable. In the AC electric field, the insulator in the cable will form dielectric loss due to leakage current and various polarizations.δ) to indicate that it not only wastes electric energy, but also makes the medium (insulator) heat up and accelerates insulation aging, so TANδIt is also one of the main parameters of the cable.
Through the measurement of capacitance and loss factor, various insulation deterioration phenomena such as insulation damping, insulation layer and shielding layer falling off can be found, so no matter in cable manufacturing or cable operation, capacitance and loss tangent value are measured. For high-voltage cables, the measurement of capacitance and loss factor is carried out under their working conditions, that is, power frequency and high voltage. Cable fault detector manufacturer Shenzhen Noyafa Electronic Technology Co., Ltd.
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