How important is the joule rating of a power-line conditioner?
It is a common misconception to put too high an importance on the joule rating of a power-line conditioner. A joule is a “watt-second,” which is a unit of energy equal to the work done when a current of one ampere is passed through a resistance of one ohm for one second. What does this mean? First, it is important to note that all surge-suppression devices are nonlinear, particularly an MOV (metal oxide varistor, the most common surge suppression device), meaning that output voltages and currents are not proportional to input voltages and currents. Therefore, the behaviour of an electronic system (power-line conditioner) containing non-linear components is very hard to model, and subsequently attempting to predict its behaviour, under constantly changing operating conditions (transient conditions), is near impossible. Second, to state the joule rating of a power-line conditioner, at best, is misleading, as a power-line conditioner’s joule rating refers to its maximum energy dissipation
