A healthy motor with good Power Quality does not guarantee a reliable system. Overall reliability can be detrimentally influenced by a defective Power Circuit. Studies found that 47% of reduced efficiency in electric motors results from high resistance connections and other Power Circuit anomalies. Power Circuit anomalies create localized heating and degradation that left alone can result in a catastrophic failure or loss of production. Similar to Power Quality, the product of a Power Circuit anomaly is elevated heat. Not only localized heating as a result of the voltage drop across the high resistance connection, but a stator winding temperature increase as a result of the circulating currents flowing though the motor windings in support of the three-phase imbalance. If the motor is already running fully loaded and at design temperature, running with a Power Circuit anomaly can exceed the design temperature, reducing the life expectancy of the motor insulation system.
Power Circuit analysis can be easily performed with the motor running or de-energized (tripped) through In-Rush/Start-Up, Voltage, Current, and Winding Resistance measurements.
To see a detailed discussion about Power Circuit Analysis and Troubleshooting view the Power Circuit Tips – Todd and Noah Podcast. https://www.youtube.com/watch?v=EAuELl2rlFQ
