An electric motor is designed so that it can provide a nominal torque Cn, at a nominal speed Nn, that is, for a nominal power Pn, we consider the expression Pn = Cn x Nn. It is important to note that the electrical losses, also known as thermal losses, change according to the square of the resistant torque, which is the load. CEA30006
If the required work of the driven machine is likely to have temporary overloads, the power of the electric motor must be a little higher than the required power. It is also important to restrict the increase in losses by performing a correct maintenance of the machines and their mechanical drive components, such as adjustment of clearances, proper lubrication and checking of alignments.
In a well-sized motor, the rugged torque must be less than the nominal torque, but if it is equal to or slightly higher, the resulting heating will be considerable. In this way, a motor considered underloaded will present a sensible reduction in the yield. The ideal loading would have to match the workload that will be done, which is often not easy to define.