Intermittent Energization and Switch Mode Power Supplies

As the proliferation of switch mode power supplies continues around the world, we are finding that in high resistivity applications, intermittent energization (a short duration programmed time on with a usually longer programmed time off), provides improved precipitator performance over full current mode operation. When working with a thyristor or SCR control system, you are limited to a minimum on time of 8.6-10 milliseconds depending on the line frequency versus modern SMPS units that allow the power to be controlled down to .1 milliseconds on to 999.9 milliseconds off. More precise control of charging of the field and finding the natural decay rate allows for better performance with some of the highly resistive coals. For more details, view the Intermittent Energization and Switch Mode Power Supplies technical paper (PDF) authored by Robert Guenther, Joong Seok Yoon, and Fran Skovran of NWL.