Application of Special Arresters on 138 kV Lines of Application Power Company
Special zinc oxide series gapped line arresters were installed on Appalachian Power Company 138 kV lines having high tower footing resistance and severe lightning exposure. This effort was part of an experiment to explore means of reducing lightning flashovers in exposed locations where low ground resistances are not feasible. Because of possible future voltage uprating of these lines, the arresters were built in the form of high strength nonporcelain mechanical struts, designed to limit phase conductor swing. This paper describes the field installation of these experimental arresters and their instrumentation and reports operating experience in 1983.
Expulsion protective gaps on 132 kv lines
During the last few years, the expulsion protective gap, consisting of an arrangement of spark gaps inside of fiber tubes and in series with an external gap, has been applied to a few medium voltage transmission lines for protection against outage due to lightning. The first extensive application of such gaps on 2 typical 132 kv lines during the past 2 lightning seasons are presented herewith. These expulsion protective gaps are shown to be an effective device for preventing lightning flashovers of a line and reducing line outage.
Lightning Investigation on a Wood Pole Transmission Line
The purpose of this paper is to report the results of an investigation made on a wood pole line. The entire line was originally very highly insulated. The splintering of the structures by lightning indicated that excessively high voltages were appearing quite frequently. Because of the high insulation a cathode ray oscillograph station was installed on the line. A total of 38 significant surges was recorded, two of these being a five million and a four and one-half million-volt surge. Analysis shows that these high surges were the results of lightning bolts striking the lines causing faults between conductors but not to ground. The data also indicate that harmful effects are caused only by direct strokes. These and current measuring records indicate that currents varying from very low values to 100,000 amperes may readily be obtained. Two methods of protection are dealt with, one utilizes a fuse, the other an expulsion lightning discharge device. The new device operated eight times, all of these operations being successful.