The causes of noise in cables include: 1) molecular friction within the dielectric; 2) changes in cable capacitance; 3) the piezoelectric effect of the cable dielectric; and 4) charge generation due to friction between the conductor and dielectric within the cable, i.e., charge separation when contact between the conductor and insulation is broken.
Low-noise cables, which utilize a thin layer of semiconductive material (0.20-0.30mm thick) extruded onto the surface of polyethylene insulation, have seen rapid development. Their noise levels are around 2-3mV. For low-noise cables operating at 400°C, a high-temperature-resistant semiconductive fiber wrapping method can be used, achieving noise levels as low as 5mV.
