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To understand how these various surge suppressors work, let's take a closer look at how three well-regarded companies - ZeroSurge, Richard Gray's Power Company, and Furman Sound - address transient-voltage surges in their products.

ZeroSurge

Leading the series-mode charge is ZeroSurge, which believes that MOV-based designs have significant design flaws that the technology can't overcome. ZeroSurge pioneered the series-mode approach.

The company's patented Wide Voltage Range filters use an input inductor that absorbs the initial surge. Capacitors then gradually release the excess energy to neutral when voltage returns to normal. Unlike MOV-based suppressors, which need to be set at a specific over-voltage level, series-mode filters can track and suppress all excess voltages.

ZeroSurge's Total Surge Cancellation filters use additional winding on the inductor - basically making it a transformer - to generate a canceling voltage that eliminates any residual over-voltage. Because surges are canceled at the output, and because the filters don't wear out, series-mode filters don't have Joule ratings, clamping voltages, or suppressed voltage ratings, which are used as benchmarks in establishing the performance of shunt-based suppressors.