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The motor wiring manufacturer has brought you the basic performance test of the wire and cable

Posted On:2017-12-19 9:00:54

Method of inspection
Routine test: is the manufacturer of all finished cable to carry out the experiment. Its purpose is to check whether the product quality meets the requirements of the technical conditions in order to find accidental defects in the manufacturing process. It is a non-destructive experiment, such as the DC resistance of the wire, insulation resistance time. And pressure test partial discharge detection.
Type test: is that the manufacturer regularly conducts comprehensive performance testing of the product, especially for a new product before it is finalized in bulk production. Or when there is a change in the structure, material, and main process of a product that may affect the performance of the cable. Through the type test: It can be tested whether the product can meet the requirements of operation, and can be compared with the old product. For example, thermal aging properties of insulation and sheath, long-term stability tests of power cables.
Acceptance test: The acceptance test of the cable after the cable is installed and laid in order to check the installation quality and find possible damage during construction. For example, pressure test after installation.
Pilot projects
1, the measurement of direct current resistance of wire
Automobile wire beam manufacturers said that the lead wire core of wire and cable mainly transmits electrical energy or electrical signals. The resistance of the wire is the main indicator of its electrical performance. When the AC voltage acts, the wire core resistance is large due to the skin effect and the adjacent effect surface is larger than the DC voltage, but the difference between the two is small when the electric eye frequency is 50Hz. The standard now stipulates that the test can only require the DC resistance or resistivity of the wire core to exceed the specified value in the standard. Through this inspection, some defects in the production process can be found: such as wire fracture or part of the single wire fracture; The cross section of the wire does not meet the standard; The length of the product is not correct, etc.. For power cables, it is also possible to check whether it will affect the allowable load flow in the operation of wire and cable products. The measurement of conductor DC resistance includes single-arm DC resistance method and two-arm DC bridge method. The latter has higher accuracy than the former. Test steps are also more complicated than the former.
2, insulation resistance test
Insulation resistance type reflects the important index of insulation characteristics of wire and cable products. It is closely related to the resistance strength of the product, the loss of medium, and the gradual deterioration of insulation materials in the working state. For communication cables, the low insulation resistance between wires will also increase the loop attenuation, the concatenation between circuits, and the long-distance power supply leakage on the lead wire core. Therefore, the insulation resistance is required to be higher than the specified value. Determination of insulation resistance can be found in the process of defects, such as insulation drying or moisture damage; Insulation is contaminated and there are conductive impurities mixed; Insulation layer cracking caused by various reasons. In the operation of wires and cables, insulation resistance and leakage current are often detected as the main basis for continued safe operation. At present, the measurement of the insulation resistance of wire and cable, in addition to the ohmmeter(rocker), is commonly used for the high resistance method(voltage-current method).
3, measurement of capacitance and loss factor
The car cable manufacturer said that the cable plus the AC voltage has a current flowing through. When the voltage is of a certain magnitude and frequency, the capacitance current is proportional to the capacitance of the cable(Cx). For ultra-high voltage cables, the current of this capacitor may reach a value that can be compared with the rated current, which is an important factor in 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.

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