Insulation resistance reflects the insulation characteristics of wire and cable products, an important indicator, it with the product of the electrical strength, dielectric loss, and insulation materials in the working state of the gradual deterioration of the relationship are closely related. For the communication cable, the line insulation resistance is too low will increase the circuit attenuation, the crosstalk between the circuit and the conductive wire on the long-distance power supply leakage, so the insulation resistance should be higher than the specified value.
Determination of insulation resistance can be found in the process of defects, such as insulation drying impermeable or sheath damage damp; insulation contamination and conductive impurities mixed with a variety of reasons caused by the insulation cracking. In the operation of wires and cables, it is necessary to check the insulation resistance and leakage current as the main basis for whether it can continue to operate safely.
The current wire and cable insulation resistance measurement, in addition to the ohm meter (shake table), the commonly used galvanometer comparison method high impedance meter method (voltage - current method).