Issue link: https://resources.mouser.com/i/1437723
12 Electrical systems and devices are designed to work within an acceptable variance of nominal voltage, which often fluctuates based on internal and external factors. For instance, the standard voltage in a home in the United States is 120 V. That voltage will vary, but any voltage that exceeds a peak of 212 V is considered a power surge. A product designed to run on the standard 120 V must be able to handle normal voltage fluctuations, and some products are also required to survive power surges. As a general rule for most circuits, any voltage above 125 percent of nominal voltage is a power surge. Power surges are additive or subtractive overvoltages that typically last for less than a half cycle of the normal voltage waveform. They cause a disturbance in the waveform that varies in duration from a few microseconds to milliseconds. During that time, the power surge can range from the 125 percent level to many thousands of volts. Studies indicate that 20 percent of transient voltages are external, coming from lightning and power utilities. The other 80 percent come from internal sources, such as load switching and inductive coupling. Voltage surges often reach a circuit through a combination of coupling types, such as a direct connection of circuits (galvanic coupling) and near-field interference (inductive and capacitive coupling, also referred to as electromagnetic interference [EMI]). Understanding the effects of power transients is complicated because of the way different coupling mechanisms can overlap to create damaging transients. Understanding the Engineering Challenges Chapter Two Understanding the Engineering Challenges "Most electrical components have safe working limits– be it voltage, current, power. If any of these are exceeded during a surge–overvoltage, overcurrent, overpower, etc.–then the component is destroyed." George Burlacu, Compliance Engineer, GVA Lighting, Inc.