A Safety Recap for Adjustable Speed Drives: The Sometimes-Overlooked Safety Concerns with Large Systems

Large engineered adjustable-speed-drive (ASD) systems are typically rated above 7 kV, with 5,000 or 10,000 hp considered engineered products and systems (i.e., one-of-a-kind or one-off designs) as opposed to off-the-shelf equipment. As such, they require more attention to application, design, system validation, and commissioning than typical off-the-shelf equipment and systems. Hazards associated with different drive topographies are sometimes overlooked during the design stage. In many cases, the design engineer considers the drive as a "black box" without sufficiently understanding the internal drive design required to identify and mitigate concerns. In some cases, manufacturers' claims may help reinforce this attitude.