Investigation of time-varying magnetic field in thyristor rectifiers of 19kA in Chlor-Alkali industry

This paper investigates the experimental and simulated time-varying magnetic field in a Chlor-Alkali plant. High current rectifier system of 19kA is modeled and analyzed. The performance is compared and evaluated on the basis of exposure guidelines from ICNIRP. The mechanical structure of current carrying conductor is simplified as infinite long busbar model and low frequency harmonic contents up to 65 kHz are considered. Thyristor rectifier generates a significant amount of low frequency magnetic field harmonic contents both at ac and dc bus-bar of rectifier infringing the limit from ICNIRP. Along with simulation analysis the experimental measurement has accurately evaluated the time-varying magnetic field in ac input bus-bar, rectifier block, dc load and bus-bar. The experimental test results partly confirm the proposed concept and simulation results. EMI factor can play a significant role in the optimal design of filter size to meet the exposure guidelines.