YPE html PUBLIC “-//W3C//DTD XHTML 1.0 Transitional//EN” “http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd”> Induction motors, both single and polyphase, are designed for use with a particular frequency of AC power. Occasionally we’re confronted with a ‘wrong’ frequency motor. In this article I’ll help you understand the ramifications. There are a large number of interacting relationships in a motor’s design. There are first order, second order and probably even third order aspects that are all balanced to produce a dependable motor with the desired characteristics. 1) Rotational speed is a direct function of the power frequency. Very simply, if you drop the frequency, the motor will slow down. Conversely, if you raise the frequency, the motor will speed up. The speed change that results will be proportional to the frequency change. 2) Cooling is a direct function of rotational speed. The motor’s fan is attached to the motor’s spinning rotor so it will experience the same speed-up or slow down the motor does. If the motor slows down, its cooling will drop (and at a faster rate than the slow d...