In 1997, a research project led by Infraspection Institute utilized instrumented motors in a controlled environment to determine the effect of excess force on installed motors. One of the primary goals of this research was to identify a location for collecting reliable temperature data.
From our research it was found that measuring the exterior of the motor bellhousing within 1″ of the output driveshaft consistently produced temperatures that were within 1 to 2 Celsius degrees of the motor windings and the inboard bearing assembly. Temperatures taken at the bellhousing were especially useful for fan-cooled motors since this area was unaffected by convective cooling from the fan.
When measuring motor temperatures, keep the following in mind: