Results of outdoor temperature-rise tests on submarine power cables installed under guards on riser pole are presented. Test data were used to determine ampacities for three steel-wire armored distribution class cables under specific solar radiation conditions. The measured data also compared well with results from an existing cable ampacity computer program. Some discrepancies, however, indicated that the program predictions could be improved if eddy-current and hysteresis losses were considered in the calculation method used for single-phase cables on riser poles. For a valid comparison between measurements and calculations, it was necessary to account for limitations in the existing computation method by conditioning some program inputs. Consequently, a technique was developed for deriving a single-valued program input that would represent the effect of time-varying solar radiation. A thermal circuit used to determine the transient response of the cable/guard system is presented, along with values for the thermal parameters of three submarine cables. A revised method used to calculate the external heat dissipation coefficient for vertical cable guards is also described.
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