Development of High-Efficiency RF Amplifier 118 MHz 300 W Module

Abstract

Abstract

Utilizing underground cable for transmission and distribution systems, the system designer has tobe careful about induced voltage and current in metal sheath so that they are not beyond limits. Too highthe induced voltage can be dangerous to equipment or related personnel. Too high the sheath current canproduce heat in the cable which affects the current rating of cable.In this paper, analysis of induced voltages and circulating currents in sheath of high voltage cablesin underground duct bank are carried out so that generalized mathematical model can be obtained. Furthermore,analysis of crossbonding of metal sheath which is usually applied for long cable will be performed.Results of this research will be equations for induced voltages and circulating currents. These equations arein the form of matrices and are general equations such that induced voltages and currents in metal sheath ofhigh voltage underground cables can be calculated regardless of number of feeders or cable formation (flat,trefoil, or other formation). Other than this, type of cables can be different. Currents in core conductors,which are the origin of voltages and currents in metal sheaths, can either be balance or unbalance.

Keywords : Underground cable; High-voltage cable; Metal sheath; Crossbond; General equation