The insulation resistance is a func

The insulation resistance is a function of many variables: the physical properties of the
insulating material, temperature, humidity, contaminants on the surface of the winding’s
insulation, etc. The effects of temperature can be compensated for by converting the IR
value to a standard temperature – 40oC as shown later in this chapter. The effects of
humidity and contaminants can not be readily taken into account. Good judgment must be
used when analyzing IR values from motors that may be wet, dirty, loaded with carbon
dust, etc.