Abstract :
The object of this composite paper is the presentation of a fairly complete description of this 220-kv. system and its operation, together with an account of some work which is being done in preparation for a third line to Big Creek. The first section is descriptive of the system and the flashover troubles, giving a detailed account of the bird theory for the cause of flashovers and of the evidence substantiating that theory, also of the measures being taken to prevent the birds from causing flashovers. The balanced relay protection for the lines and the relay installations to control a flashover or other accidental ground in case the balanced relays are not allowed to function, together with some information obtained from a study of flashovers are contained in the second section. Section three is devoted to a study which is being made to determine the mechanical and electrical characteristics which will give a most economical third line from Big Creek to Los Angeles. Both aluminum and copper conductors of various large sizes and working at various tensions are considered, and tower locations on ten miles of profile were made. Section four reports that vibration, particularly in the longer spans, has apparently caused some failures of ground wires and possibly of conductors. Frequencies of 13 to 30 cycles per second and amplitudes up to one inch have been recorded. The vibrations are believed to be due to air currents, but no means of preventing them has been discovered. In order to minimize the effects of vibration, it is proposed to reduce the weight of the dead end clamps so that the shocks will be transmitted to the tower connections instead of being absorbed at the outer end of the clamps as at present. A new light weight dead end clamp has been designed and is being tested under service conditions. In section five it is concluded that for a high voltage line of large capacity the high cost per mile and heavy tonnage to be transported during construction requi- e careful location work to strike the most economical balance between a straight line and one most easily accessible for construction and maintenance. Right-of-way cost must also be given consideration, together with many other factors which make up the total cost. The complexity of the problem and the large amount of money involved with consequent opportunity for saving, warrant unusual methods of reconnaissance and survey, and purchasing right of way.
