الفهرس 
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Abstract
High voltage underground cables are frequently used to
transmit electrical power from generating stations to load
centers. The maximum current carrying capacity of these
cables is governed by the maximum permissible temperature
of the insulating material. In order to increase cable ampacity,
artificial cooling systems are used so that the insulation
temperature can be kept at its allowable value.
This thesis presents a study of both steady state and
transient thermal performance of artificially cooled cables. A
computer program has been developed to compute thermal
resistances and capacitances as well as temperature
distribution along the cables and the coolant system. In
addition the increase in temperature due to the interruption of
water cooling has been determined. The effect of system
configuration on current carrying capacity has been studied for
both steady state and transient thermal performance.
Furthermore, the maximum allowable time duration for
coolant interruption have been determined for different
cooling systems.
This study shows that the most efficient method to
increase the maximum current carrying capacity is the increase
of the coolant flow rate, but it is limited by the maximum
allowable pressure that the pipes can withstand. Also, from the
system configuration point of view the most reliable one is the
flat formation cooled by two pairs of pipes, relative to the other considered systems. from the thermal transient study,
the obtained results realize that the time required for insulation
system to attain its maximum allowable temperature, after
coolant interruption, is long enough to achieve the repairing of
the cooling system without load interruption.
This thesis consists of six chapters. Chapter (1) is an
introduction. Chapter (2) gives a brief review about artificially
cooled cable systems. Chapter (3) presents steady state and
transient thermal analysis. Chapter (4) Presents steady state
thermal performance. Chapter (5) Presents the transient
thermal performance. Chapter (6) Presents the main
conclusions.
Key Words:
Cable, Artificial Cooling, Current, Performance, Steady
State, Transient, Thermal.