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Study to determine the basic insulation level requirements for a prototype 1200 kV CGIT cable system

Technical Report ·
DOI:https://doi.org/10.2172/6029702· OSTI ID:6029702

The required lightning impulse withstand characteristics of a prototype 1200 kV CGIT System were studied. It was assumed that lightning overvoltages would be introduced into the CGIT System due to lightning strokes which terminate on the overhead transmission system connected to the CGIT system. A detailed analysis of several proposed configurations for 1100 to 1200 kV transmission lines indicated that the most probable form of lightning overvoltage introduced into the CGIT System would be caused by shielding failures rather than blackflash occurrences. Following this conclusion, a single phase digital transient program was utilized to calculate the transient overvoltages which would appear within the CGIT System for system lengths of 600 ft, 2 miles, 10 miles, and 50 miles. Part of these simulations modeled surge arresters at both ends of a CGIT System representing a cable system interposed in an overhead line or a cable system terminating at an air-insulated substation. A second group of computer simulations modeled a surge arrester at one end only to represent the situation where a CGIT System terminates at a gas insulated station where the disconnects are opened and no arrester is applied within the gas insulation. Two types of surge arresters were modeled in this study: an arrester having protective characteristics extrapolated from present designs and ceramic oxide arresters.

Research Organization:
Westinghouse Electric Corp., Pittsburgh, PA (USA). Advanced Systems Technology Div.
Sponsoring Organization:
USDOE
OSTI ID:
6029702
Report Number(s):
DOE/ET-2061-1
Country of Publication:
United States
Language:
English