Voltage sags are some of the most common types of power quality disturbances and can cause industrial control devices to fail. Because equipment trips of these widely applied devices can be devastating, the Power Quality Group undertook a testing project to evaluate sag performance for a variety of industrial control devices, such as motor contactors, control relays, small adjustable-speed drives, proximity sensors, and programmable logic controllers. This report will help you to make informed decisions about improving the power system performance, improving equipment ride-through characteristics, and effectively applying power-conditioning equipment to mitigate voltage sag problems. (PQG-2; May 2003; 38 pages)