Determination of permissible underground power cable installation -- A calculation method on cable ampacity based on heat generation
- Bechtel Power Corp., San Francisco, CA (United States)
In a power plant, it is often necessary to install a medium voltage underground cable system to transport the high capacity of auxiliary transformer power output to switchgear lineups. Installation of high current carrying power cable is often limited by the resistive heat generated by the passage of high current. Because heat dissipation in cable routed underground is affected by the soil temperature, soil resistivity, and cable depth, a systematic analysis is necessary to determine the permissible cable ampacity in each cable among the group of cables in any combination of underground cable and duct arrangements. The calculation will determine the medium allowable ampacity in such a system. Depending on the underground cable and duct arrangements, the current carrying capacity of similar cable systems may be different. The impedance of each phase of a cable will be different in a multi-conductor per phase cable system if the cable and duct arrangements are not symmetrical. The calculation will also determine any unbalanced phase impedances and calculate the unbalanced phase currents.
- OSTI ID:
- 94250
- Report Number(s):
- CONF-950414--
- Country of Publication:
- United States
- Language:
- English
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