Fault Clearing and Overload Capacity

This is a measure of a unit’s ability to tolerate levels of current higher than the rated current without sustaining short or long term wear or damage. Many electric devices, like motors, magnets, transformers, etc., require a large inflow of current when started (inrush current). A "typical" AC motor has an inrush of 500 to 1000% of the normal current that peaks in a few cycles and then decays to normal levels within 10 to 30 cycles. Power conditioners with ratings like 1000% for 1 cycle might not be good choices for industrial or commercial applications with frequent or large inrush current. For this measurement, the higher the percentage and the longer the time at that percentage, the better the unit should stand up to high inrush applications.

Fault clearing has a relationship with overload capacity in that both describe the ability of the power conditioner to operate for some period of time at current levels above the unit's rating. If a power conditioner cannot pass enough current without tripping or shutting down, downstream equipment and protective devices may not be able to "clear" or reset themselves, thus creating an annoying operational problem.