Distribution of Ground Fault Currents Along Transmission Lines -- An Improved Algorithm
The calculation of fault current distribution between ground wires and ground is important for the operation of modern power systems. A new method is presented based on an approach whereby the current distribution is solved through the computation of driving-point impedances. The method is applied to three phase systems with mutual couplings between conductors (phase and ground, respectively) included. Currents computed by this method and methods published in recent literature are compared and are found in good agreement. Results show that the method is more efficient in terms of CPU time and memory space.
Computer-aided calculations of earth potential rise in high voltage overhead lines
High voltage overhead power lines with earth wires comprise towers made of conductive material. Some towers are in locations where people can be expected to be either for a long time or for a short time but very frequently. Evaluation of shock hazard near such towers requires calculation of line-to-earth short-circuit current, earth current and especially earth potential rise. Number of towers in high voltage power lines can exceed 100. Thus, evaluation of effectiveness of protection against electric shock is time-consuming, so computer software for fast calculation of earth potential rise can be useful. This paper presents a method of computerized calculation of earth potential rise and earth current distribution in overhead lines with earth wires. The example results of calculations are presented for two selected cases of transmission system.
Laminar heat or mass transfer in rectangular channels and in cylindrical tubes for fully developed flow: comparison of solutions obtained for various boundary conditions
Abstract A comparison is made of results obtained with various boundary conditions at the wall of the channels. By comparing blood Sherwood numbers for finite wall resistance with those for constant concentration boundary condition only a small variation is found for various points along the blood channel.