PROCEDIMENTO DI RILEVAZIONE DEL L USURA DI UNA LINEA IMMERSA IN UN MEZZO CONDUTTORE E RACCHIUDENTE UNA CONDOTTA OD UN CAVO ELETTRICO

摘要

To detect wear in an insulating sheath on the outer surface of a submerged line having metal armouring (1), the line constants R, C, L and G of a line in good condition are used to calculate the apparent impedance Za in accordance with the equations: R being the resistance, C the capacity, L the inductance, G the conductance, Zc the characteristic impedance, Zu the load impedance,w the pulsation, f the frequency of the current, I the length of the line, n the propagation constant according to n = 2ROOT (R+jLw) (G+jCw> the line being considered to be formed between the armouring (1) and the conducting medium surrounding the outer insulating sheath; then during use thereof on the service site in connecting its metal armouring (1) to a measuring apparatus the surrounding liquid providing the return path to a connection (2), in periodically injecting a low frequency current and in measuring the value of its apparent impedance Za whose deviation with respect to the initial apparent impedance signifies wear of the insulating sheath.