Failsafe Motor Control Design to Prevent Runaway Motors

This article provides the background for and summary of key barriers one should consider when analyzing motor control designs in order to prevent runaway motors, especially runaway motor-driven pumps against closed valves with the potential to lead to fire. A Failure Modes and Effects Analysis (FMEA) is used to analyze typical motor control designs with the intent of determining a means of preventing a runaway condition due to failure of any one component. Following the determination of key barriers, the pipeline industry is surveyed to assess the prevalence of each barrier in similar operations and to look for additional best practices not previously documented. Additional challenges are discussed, and conclusions are presented with final recommendations for consideration to avoid runaway motors, especially those that drive pumps with the potential to run against closed valves, possibly leading to fire.