Pipe-type cable cooling system.
Savilonis, Brian J.
NSTAR Gas & Electric Company has identified the need to increase the capacity of two high-pressure fluid-filled pipe type 115 kV circuits in the transmission system. For reliability purposes, 1125 amps are needed when one circuit is in service. The options that were explored that would aid in increasing the ampacity for each circuit included replacing the conductors, replacing the potheads, replacing some of the existing oil with a lower viscosity oil, adding one or two heat exchangers, adding an oil return pipe, installing a completely new third circuit, and various combinations of these options. Schematics for each option were designed to determine circulation and cooling lengths. Flow rate and ampacity calculations were then completed using these lengths to determine the best solutions, as were cost estimates. It was determined that the most cost efficient way to increase the capacity of the circuits and to still be able to produce the 1125 amps needed when one circuit is out of service, is to install a third circuit in conjunction with the two existing ones.
Worcester Polytechnic Institute
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