Cable Impedance Measurement and Verification Method

This paper present detail description on determining cable parameters of an electrical power cable. A method known as short-open method is employed in this work where the series parameters of a two wire cable are determined by shorting the end of the cable while the shunt parameters are extracted by opening the end terminal of the cable. Network analyzer and LCR meter are utilized in carrying out the short-open method. The measured parameters from both network analyzer and the LCR meter are compared and verified by finding the propagation delay of the cable through an experiment. The propagation delay value from the experiment is compared to a propagation delay value computed from the primary parameters to check for accuracy. The experimental setup constituted of a DSP board, 30kHz buck converter, 150V DC power supply and a 16m power cable. The 16m cable was selected because it was much easier to manage in the laboratory. The cable parameters were extracted at 30kHz frequency which is the same as the buck converter switching frequency. At 30kHz a propagation delay of 84ns was obtained for LCR meter while network analyzer had 83ns. Propagation delay from using the buck converter gave a propagation delay of 84ns which is the same as computed propagation delay value from LCR meter.