Discharge-Resistant Characteristics of the Polyethylenes for Wire and Cable

Surface discharge phenomena associated with unshielded nonmetallic sheathed power cables, particularly in the 3000- to 15 000-volt classifications, have been the subject of considerable research. These cables have induced surface voltages which are responsible for surface leakage currents and associated surface discharges, which combine to form a phenomenon generally referenced as surface-tracking, particularly in the presence of wetted surface contaminants. Unpigmented polyethylenes are highly resistant to surface tracking. However, when formulated for protection from sunlight and weathering, the discharge resistance may be materially reduced. This paper describes the development and evaluation of discharge-resistant thermoplastic or chemically cross-linked polyethylenes.