Cost-benefit analysis of solutions protecting industrial processes with variable speed drives against voltage sags

Voltage sags can cause considerable financial damage in industrial processes containing variable speed drives. Many solutions exist to protect these sensitive processes, varying from modifications within the process itself to restructuring the supplying grid. In many cases, the only possibility to reduce the damage is to install mitigation equipment between the grid and the sensitive process such as an Uninterruptible Power Supply (UPS). However, protecting the enure process by a dynamic or static UPS often turns out to be too expensive. In the last decade, alternative mitigation methods have been developed that prevent most of the process outages at a much lower cost This paper analyses these methods and shows how to choose the most cost effective one.