These motors are made for the application requirements of variable quickness drive systems. We offer both the subsequent 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 pumps and fans.
Due to rapid switching and reflections in the cables, motors are subject to more voltage stress 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 motor winding insulation and may cause it to break down, resulting in possible sparking. ABB recommends:
Between 500 V and up 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 will need reinforced winding insulation and the drive is required to have a du/dt filter.
If the cable duration between the 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 something for controlling the rotational acceleration of an alternating electric current electric electric motor. It controls the frequency of the electrical energy supplied to the engine. A adjustable frequency drive is definitely a specific type of adjustable-quickness drive. Variable-frequency drives are also called adjustable-frequency drives (AFD), variable-velocity drives (VSD), AC drives, or inverter drives.
Automatic frequency control contain an primary electric circuit converting the alternating current into a immediate current, then converting it back to an alternating current with the mandatory 
frequency. Internal energy reduction in the automated frequency control is ranked ~3.5%
Variable-frequency drives are widely used on pumps and machine device drives, compressors and in ventilations systems for large buildings. Variable-frequency motors on supporters save energy by enabling the volume of atmosphere moved to match the system demand.
Reasons for employing automated frequency control may both be linked to the functionality of the application form and for conserving energy. For instance, automatic frequency control is used in pump applications where in fact the flow is usually matched either to quantity or pressure. The pump adjusts its revolutions to confirmed setpoint via a regulating loop. Adjusting the stream or pressure to the actual demand reduces power usage.
An AC motor speed control-also referred to as a adjustable frequency drive, adjustable frequency drive, variable swiftness drive, adjustable speed drive and AC inverter-is an electro-mechanical object that can be utilized to change the output swiftness of an AC motor by adjusting the input frequency into the motor.