The selection of qualified wire and cable products is related to the safety of people's production and life. For ordinary consumers, in addition to mastering how to select qualified wire and cable products, it is necessary to understand the routine monitoring knowledge of wire and cable. In the quality detection of wire and cable, there are mainly the following important indicators. The following Qingdao wire and cable manufacturer to introduce you:

Insulation resistance test:

The insulation resistance type reflects the important index of the insulation characteristics of wire and cable products, which is closely related to the electrical strength of the product, the loss of the medium, and the gradual deterioration of the insulation material in the working state. For communication cables, too low insulation resistance between wires will also increase loop attenuation, cross-talk between loops and long-distance power supply leakage on the conductive wire core, so the insulation resistance should be higher than the specified value.

Measuring insulation resistance can find defects in the process, such as dry insulation or sheath damage and moisture; Insulation is contaminated and conductive impurities are 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 whether they can continue to operate safely.

At present, in addition to the measurement of the insulation resistance of wire and cable, in addition to the ohmmeter (swing meter), the commonly used galvanometer comparison method and high resistance meter method (voltage-current method).

Measurement of capacitance and loss factor:

The cable plus AC voltage, there is a current flow, when the voltage amplitude and frequency is certain, the size of the capacitor current is proportional to the cable capacitance (Cx). For ultra-high voltage cables, the current of this capacitor may reach a value that can be compared with the rated current, which becomes an important factor limiting the cable capacity and transmission distance. Therefore, the cable capacitance is also one of the main electrical performance parameters of the cable.

In the AC electric field, the insulator in the cable will form a dielectric loss due to the existence of leakage current and various polarization, expressed by the dielectric loss factor or loss Angle tangent value (TAN), which not only wastes electrical energy, but also causes the dielectric (insulator) to heat up and accelerate insulation aging, so TAN 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 moisture, insulation layer and shield layer shedding can be found, so capacitance and TAN are measured in both cable manufacturing and cable operation. The measurement of high voltage cables, Cx and TAN are carried out under their working conditions, that is, power frequency high voltage, usually using high voltage Schilling bridge, and this year has also begun to use current ratio transformer bridge.

Partial discharge measurement:

There is basically no local power generation for oil-filled cables; Even if the oil paper cable has partial discharge, it is usually very weak such as a few PCS, so these cables can be unexpected partial discharge in the factory test. For extruded cable, not only the possibility of partial discharge, but also the damage of partial discharge to plastic and rubber is more serious, with the improvement of voltage level and the improvement of working field strength, this problem is more serious, so for high voltage extruded cable, partial discharge measurement should be done in the factory test.

There are many methods for measuring partial discharge. The discharge pulse can be measured according to the instantaneous charge exchange generated by discharge (electrical measurement method). It can also measure its voltage according to the ultrasonic wave generated during discharge (acoustic measurement method); The intensity of the light can also be measured according to the light generated by the discharge (photometry). For cables are basically used electrical measurement method.

Qingdao Tianxing Cable Co., Ltd. focus on supporting wire and cable production customization manufacturers, main: exports to more than 40 countries and regions around the world, the annual production capacity of 1 billion yuan. 6000 square meters of storage, standing hundreds of millions of inventory, order demand for rapid distribution and delivery, large prices more favorable. Qingdao cable manufacturer hotline: 16678668098