An increase in voltage applied to equipment above its nominal rating may cause failure of the components
depending upon the magnitude and frequency of occurrence. Electronic devices, including ASDs,
computers, and electronic controllers, may show immediate failure modes during these conditions. (Many
modern electronic devices incorporate integral overvoltage trips in their designs. The actual electronics are
often not disconnected from the source if the device trips and can still incur damage.) Transformers, cables,
busses, switchgear, CTs, PTs and rotating machinery may suffer reduced equipment life over time. A
temporary increase in voltage on some protective relays may result in unwanted operations while others
will not be affected. Frequent voltage swells on a capacitor bank can cause the individual cans to bulge
while output is increased from the bank. The visible light output from some lighting devices may be
increased during a temporary swell. Clamping type surge protective devices (e.g., varistors, silicon
avalanche diodes) may be destroyed by swells exceeding their maximum continuous operating voltage
rating.