Surge and High-Frequency Propagation in Industrial Power Lines

Laboratory measurements were made on a three-conductor line, with or without steel conduit sheath (typical of single-phase 120/240-V systems), to determine the attenuation of surges and the response to steady excitation at frequencies in the range of 100 Hz-10 MHz. Line length ranged from 75 to 225 m. Impedance matching was maintained at the sending end, while at the receiving end various loads (matched or mismatched) were included. A nonlinear load was also used, illustrating the side effects of connecting a surge protective device at the end of the line.