Zero Energy Storage Voltage Sag Correctors for Industrial Applications

Voltage sags represent perhaps the major cause of productivity loss for a wide range of industrial automation equipment and continuous processes. Various solutions are available to provide ride-through and to mitigate the impact of such power disturbances, including products such as UPS, DVR and DySC. Because it is prohibitively expensive to protect against all possible power disturbances, all sag correctors rely on a statistical approach to specifying which events will be protected against, and are based at least in part, on the principle of using stored energy to allow converter operation when a voltage-sag occurs. Based on an exhaustive analysis of significant voltage sags recorded mainly at larger industrial plants, it is seen that a new approach to sag correction can be identified that is more compact, has fewer catastrophic failure modes and potentially lower cost. The concept of a ´zero energy sag corrector´ or ZESC is introduced, with analysis to compare the level of protection provided against other more established sag correctors. It is seen that the ZESC system protects susceptible equipment against over 96% of all power disturbances.