Choosing with the use of catalog data
Using the mean values for power Pmi, torque Mmi and current Imi that were
computed for less demanding conditions a motor can be chosen using catalog
data, whereby the corresponding catalog data may not be less than the computed
averages:
P
mi ≤ Pn, Mmi ≤ Mn, Imi ≤ In
Most motor applications can be assigned to the 9 duty types S1 through S9. In
more complex situations, where a definite selection is not possible, a similar
duty type can be defined and then converted to S1. This method, however,
requires detailed knowledge with respect to thermal time constants and cooling
conditions. The motor manufacturer can supply these data.