Hi,
I am in the process of designing a DIY power supply that is running on a 230V AC. I would like to add a varistor to the circuit as a safety feature for surge protection, but I am not sure what the specs should be. 230V RMS should equal ~325V peak voltage. Should I select a varistor that is rated slightly higher that the peak voltage like 350V or would a 230V, 250V, 275V or 300V varistor work? How do I know which is the best for my application? What should he energy spec (J) be?
Thanks!