When choosing a electric motor for an application, a primary consideration is the speed range it’ll be operated in. When a motor is operate substantially slower than its ranked base speed, a number of 
potential adverse effects will come into enjoy, including reduced cooling performance, reduced power efficiency and a alter in the motor’s speed and torque features. To mitigate this problem, some motors and speed controllers have been designed especially to drive lots at low speeds with specific control.
Most domestic and industrial motor applications use 3-phase asynchronous induction motors, which operate at a speed that is determined by the frequency of the supply power. When a credit card applicatoin operates at a continuous speed, the only thing that is required could be a gearbox or quickness reducer that brings the engine speed down to the required level. However, many applications need the swiftness of the electric motor to be various during operation.
This is normally achieved utilizing a VFD or Adjustable Frequency Drive, which controls the speed by modifying the frequency fed to the motor. Selecting the most appropriate motor and VFD type depends upon a number of factors, however, it’s important to initial look at the way the characteristics of a electric motor change when the velocity is reduced.
A motor usually includes a base speed, specified by the manufacturer, that it is certainly made to operate at. However, if a electric motor is managed below the base speed, it may experience reduced performance of the coolant system. Especially with frequently used Totally Enclosed Lover Cooled (TEFC) and ODP (Open Drip Proof) motors, where the cooling program consists primarily of a shaft-mounted lover, a reduction in speed outcomes in decreased airflow over the motor and lack of cooling, and high temperature buildup occurs. Particularly when the motor is operated with full torque at low speeds, heat can speed reducer gearbox quickly build up inside the motor to harmful levels.