Analysis of forced cooling of compressed gas insulated transmission lines. Final report

Technical Report · Wed Dec 01 00:00:00 EST 1976

DOI:https://doi.org/10.2172/7223522· OSTI ID:7223522

Cookson, A. H.; Lapen, R. J.; Kothmann, R. E.

A thermal and cost analysis of forced cooling of buried, compressed gas insulated transmission lines (CGIT) was made. Only direct cooling of the sheath is considered, with water coolant flowing in aluminum pipes integrally extruded or directly bonded to the CGIT aluminum sheath. Both isolated phase and three conductor CGIT systems are considered with maximum voltage rating from 145 to 1200 kV. The lines are the designs and sizes based on present practice of self cooled systems. The CGIT lines have aluminum conductors and sheaths, and are filled with SF/sub 6/ at a pressure of 50 psig. The thermal analysis shows that cooling the sheath is an efficient technique of forced cooling CGIT lines, relying on the efficient thermal processes in the SF/sub 6/ inside the line to convey the heat from the conductor to the sheath. For a maximum sheath temperature of 60/sup 0/C, the current rating can be doubled for all voltage ratings without exceeding the maximum conductor temperature of 100/sup 0/C. Still higher current ratings are possible with reduced maximum sheath temperature at an increase in cooling system costs. The total system costs of installing buried, forced cooled CGIT lines are calculated for the isolated phase and three conductor CGIT lines for 145 kV to 1200 kV at the various current ratings. The total installed cost, including forced cooling and present worth of losses, is lower for the three conductor system by 10 percent to 15 percent at voltage up to 362 kV, and 5 percent lower at 550 kV. At higher voltages the three conductor system will be too large to be practicable.

• Research Organization: Westinghouse Electric Corp., Westborough, MA (USA). CGIT Lab.
• OSTI ID: 7223522
• Report Number(s): EPRI-EL-228
• Country of Publication: United States
• Language: English

Related Subjects

24 POWER TRANSMISSION AND DISTRIBUTION
EHV AC SYSTEMS
GAS-INSULATED CABLES
COST
HVAC SYSTEMS
UHV AC SYSTEMS
COOLING
FORCED CONVECTION
PERFORMANCE
POWER TRANSMISSION LINES
SULFUR FLUORIDES
THERMAL ANALYSIS
UNDERGROUND POWER TRANSMISSION
AC SYSTEMS
CABLES
CONDUCTOR DEVICES
CONVECTION
ELECTRIC CABLES
ELECTRICAL EQUIPMENT
ENERGY TRANSFER
EQUIPMENT
FLUORIDES
FLUORINE COMPOUNDS
HALIDES
HALOGEN COMPOUNDS
HEAT TRANSFER
POWER SYSTEMS
POWER TRANSMISSION
SULFUR COMPOUNDS
200301* - Power Transmission & Distribution- AC Systems
EHV & UHV- (-1989)