DC Motor Field – Trend is Your Friend

When discussing motor reliability we often say “Trend is Your Friend”, and this is never more true than if you are troubleshooting a DC motor. A common beginning to troubleshooting a DC motor begins with the operator complaining about sluggish or unusual speed control. If the motor reliability team has baseline MCE® data on the field inductance they will be able to easily identify if the root cause of the speed control problem is a field pole fault. Unfortunately, if there is no baseline inductance data to trend from, the team will be in a tough spot and will be relying heavily on ground wall RTG (Resistance-To-Ground) as a primary indicator of the DC motor health. RTG readings on a DC motor, although an important metric, are all too often the only thing used to determine the life expectancy or asset health of DC motors. The operator may be dealing with shorted turns in the field pole, causing poor or reduced speed control of the DC motor, all the while having perfectly normal and acceptable RTG readings. To see this exact scenario visit the PdMA YouTube channel to see our latest case study, DC Field Failure In A Pulp and Paper Mill.