These motors are designed for the application requirements of variable velocity drive systems. We offer both the subsequent types of motors:
• Constant Torque: Motors particularly designed to handle continuous torque loads, such as for example conveyors, positive displacement pumps, cranes, etc.
• Variable Torque: Motors specifically designed to handle variable torque loads such as pumps and fans.
Due to speedy switching and reflections 
in the cables, motors are subject to more voltage stress in the windings when fed by frequency converters than with sinusoidal supply voltage. The effect of these voltages is definitely an increase as high as 2.5 times the motor’s nominal voltage. This stresses the engine winding insulation and will cause it to break down, resulting in possible 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 have got a du/dt filter.
If the cable duration between your drive and engine is higher than 150 meters and the voltage is between 600 and 690 V, the electric motor must have reinforced winding insulation.
A variable-frequency drive is a system for controlling the rotational velocity of an alternating current electric engine. It handles the frequency of the electrical energy supplied to the engine. A variable frequency drive is a specific type of adjustable-speed drive. Variable-frequency drives are also known as adjustable-frequency drives (AFD), variable-rate drives (VSD), AC drives, or inverter drives.
Automatic frequency control consist of an primary electric circuit converting the alternating current into a immediate current, then converting it back into an alternating current with the required frequency. Internal energy reduction in the automatic frequency control is ranked ~3.5%
Variable-frequency drives are trusted on pumps and machine tool drives, compressors and in Variable Drive Motor ventilations systems for large buildings. Variable-frequency motors on enthusiasts save energy by permitting the volume of air flow moved to complement the system demand.
Reasons for employing automated frequency control can both be related to the functionality of the application form and for saving energy. For instance, automatic frequency control is used in pump applications where the flow is matched either to volume or pressure. The pump adjusts its revolutions to a given setpoint via a regulating loop. Adjusting the movement or pressure to the actual demand reduces power usage.
An AC motor velocity control-also referred to as a adjustable frequency drive, adjustable frequency drive, variable speed drive, adjustable rate drive and AC inverter-is an electro-mechanical object that can be utilized to change the output quickness of an AC motor by adjusting the input frequency in to the motor.