These motors are created for the application requirements of variable quickness drive systems. We offer both the following types of motors:
• Constant Torque: Motors particularly designed to handle constant torque loads, such as conveyors, positive displacement pumps, cranes, etc.
• Variable Torque: Motors specifically designed to handle variable torque loads such as for example pumps and fans.
Due to speedy switching and reflections in the cables, motors are at the mercy of more voltage tension in the windings when fed by Variable Drive Motor 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 electric 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 will need to have a du/dt filter.
Above 600 V, the motor will need reinforced winding insulation and the drive is required to have a du/dt filter.
If the cable length between your drive and engine is higher than 150 meters and the voltage is between 600 and 690 V, the engine will need to have reinforced winding insulation.
A variable-frequency drive is a system for controlling the rotational velocity of an alternating current electric motor. It settings the frequency of the electrical power supplied to the engine. A adjustable frequency drive can be a specific kind of adjustable-speed drive. Variable-frequency drives are also called adjustable-frequency drives (AFD), variable-speed drives (VSD), AC drives, or inverter drives.
Automatic frequency control consist of an primary electrical circuit converting the alternating current into a direct current, then converting it back to an alternating electric current with the required frequency. Internal energy reduction in the automated frequency control is ranked ~3.5%
Variable-frequency drives are widely used on pumps and machine tool drives, compressors and in ventilations systems for large buildings. Variable-frequency motors on fans save energy by permitting the volume of surroundings moved to complement the system demand.
Reasons for employing automatic frequency control can both be related to the features of the application and for saving energy. For example, automatic frequency control is utilized in pump applications where the flow is usually matched either to quantity or pressure. The pump adjusts its revolutions to confirmed setpoint via a regulating loop. Adjusting the movement or pressure to the real demand reduces power consumption.
An AC motor swiftness control-also known as a adjustable frequency drive, adjustable frequency drive, variable speed drive, adjustable acceleration drive and AC inverter-is an electro-mechanical object that can be used to change the output velocity of an AC engine by adjusting the input frequency in to the motor.