Power Capacity of Transmission Lines (Case Study of Coaxial Cable)

Abstract

The matrix of average power over frequency provided for each cable type is often used to evaluate the power capacity of transmission lines. There are two potential failure modes in cables also used to transmit high peak power. One is voltage breakdown; and the other is overheating. The major concern associated with application of peak power is breakdown due to high potential. In this paper, we have used coaxial cables as a case study to evaluate the power capacity of transmission lines. The study shows that the power capacity of transmission line also depends on the cable sizes and types and limited by voltage breakdown which occurs at a field strength of about E_d = 3x10⁶V/m room temperature at sea level pressure.  In addition, if there are reflections on the line or guide, the power capacity is further reduced. It is believed that the power capacity of the transmission line can be increased by pressurizing the line with air or an inert gas, or by using a dielectric.

Keywords: Impedance, Power Capacity, Transmission Line, Voltage Breakdown, Dielectric Strength.