NOYAFA Electronic specializing in testing instruments and cable testers for 16 years
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NOYAFA Electronic specializing in testing instruments and cable testers for 16 years
Author: Noyafa–Cable Length Tester
Key points of cable inspection What are the general inspection points of cable inspection? Key points of cable inspection. 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 primary goal of its electrical performance, and now the specification stipulates: to detect whether the DC resistance or resistivity of the wire core exceeds the value specified in the specification.
The primary purpose of this inspection is to find some defects in the production process: such as wire cracking or part of the single wire cracking; wire cross-section does not meet the specification; 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 of the wire and cable products in operation. 2. Test of insulation resistance: Insulation resistance is an important goal of 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 insulating materials under working conditions.
Determination of insulation resistance can find the shortcomings in the process: such as the insulation is dull 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 is required to 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 primary basis for continued safe operation.
3. Measurement of capacitance and loss factor: When the cable is added with an AC voltage, there will be current flowing. When the amplitude and frequency of the voltage are constant, the size 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 constraining the cable capacity and transmission distance. Therefore, the capacitance of the cable is also one of the primary electrical performance parameters of the cable.
In the communication electric field, the insulator in the cable will form dielectric loss due to leakage current and various polarizations.δ) to show that it not only wastes electrical energy, but also makes the medium (insulator) heat up and accelerates insulation aging, so TANδIt is also one of the primary 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 production 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 its working conditions, that is, power frequency and high voltage.
What are the general inspection points for cables? Cable inspection focus. Shenzhen Noyafa Electronic Technology Co., Ltd.
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