Impact of Environmental Effects upon Transmission Performance Data Grade Cables

摘要

The performance change of data grade cables is investigated as a function of an environmental treatment. It is shown, that - the temperature coefficient of attenuation increase, using commercially available jacket materials may be substantially higher than indicated in the standards. - the sensitivity to humidity of data grade cables is due to the moisture pick-up of the surrounding jacketing material. This effect is reversible at room temperature and to a large extent also at elevated temperature. - the aging of the jacket material and a migration of the plasticizer into the insulating materials may substantially increase the attenuation. It is shown, that primarily polyolefin insulations are susceptible to plasticizer ingress from the surrounding jacketing material, though at low frequencies, up to approximately 5 MHz, also fluorinated ethylene-propylene insulations are affected as well by aging of the cable. The mechanism leading to this effect could not yet be assessed. The paper focuses on development of test methods to determine the environmental impacts. It is mandatory to specify such test methods, in order to obtain comparable data. Some recommendations are given as to the selection of proper cable designs to minimize the environmental impacts.