These motors are made for the application requirements of variable speed drive systems. You can expect both the subsequent types of motors:

• Constant Torque: Motors specifically designed to handle constant torque loads, such as for example conveyors, positive displacement pumps, cranes, etc.
• Variable Torque: Motors particularly designed to handle variable torque loads such as pumps and fans.
Due to quick switching and reflections in the cables, motors are at the mercy of more voltage stress in the windings when fed by frequency converters than with sinusoidal supply voltage. The result of these voltages can be an increase as high as 2.5 times the motor’s nominal voltage. This stresses the motor winding insulation and can cause it to breakdown, resulting in feasible sparking. ABB recommends:

Between 500 V or more to 600 V, the motor needs to have reinforced winding insulation, or the drive must have a du/dt filter.
Above 600 V, the motor needs to have reinforced winding insulation and the drive is required to possess a du/dt filter.
If the cable duration between the drive and motor is greater than 150 meters and the voltage is between 600 and 690 V, the engine must have reinforced winding insulation.
A variable-frequency drive is something for controlling the rotational velocity of an alternating electric current electric electric motor. It regulates the frequency of the electrical power supplied to the motor. A adjustable frequency drive is certainly a specific kind of adjustable-swiftness drive. Variable-frequency Variable Drive Motor drives are also called adjustable-frequency drives (AFD), variable-acceleration drives (VSD), AC drives, or inverter drives.

Automatic frequency control consist of an primary electrical circuit converting the alternating electric current into a direct current, then converting it back to an alternating electric current with the required frequency. Internal energy loss in the automated frequency control is ranked ~3.5%
Variable-frequency drives are trusted on pumps and machine tool drives, compressors and in ventilations systems for large buildings. Variable-frequency motors on fans save energy by allowing the volume of air flow moved to complement the system demand.
Reasons for employing automatic frequency control can both be linked to the functionality of the application and for saving energy. For example, automatic frequency control is used in pump applications where the flow is definitely matched either to volume or pressure. The pump adjusts its revolutions to confirmed setpoint with a regulating loop. Adjusting the circulation or pressure to the actual demand reduces power usage.
An AC motor velocity control-also known as a variable frequency drive, adjustable frequency drive, variable acceleration drive, adjustable velocity drive and AC inverter-is an electro-mechanical object that can be used to change the output speed of an AC engine by adjusting the insight frequency in to the motor.