Statistical evaluation of telephone noise interference caused by AC power line harmonic currents

A statistical approach is used to evaluate the limits for harmonic currents in AC power lines, the goal being to prevent excessive telephone noise interference voltages in subscriber cables in rural areas. The analysis is based on a Monte Carlo simulation which takes into account the effect of the experimental probability distributions of the relevant parameters. It is shown that under Finnish conditions, the properties of communication cables permit equivalent disturbing phase currents of 8 to 10 A. The digital exchanges permit approximately the same currents. Some new telephone types that have a low balance may make it necessary to limit the currents to a level that is somewhat lower