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 frequency converters than with sinusoidal supply voltage. The result of these voltages can be an Variable Drive Motor increase of up to 2.5 times the motor’s nominal voltage. This stresses the engine winding insulation and may cause it to break down, resulting in possible sparking. ABB recommends:
Between 500 V 
or more to 600 V, the motor will need 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 length between the drive and electric motor 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 swiftness of an alternating current electric motor. It controls the frequency of the electrical power supplied to the engine. A adjustable frequency drive can be a specific type of adjustable-quickness drive. Variable-frequency drives are also known as adjustable-frequency drives (AFD), variable-rate drives (VSD), AC drives, or inverter drives.
Automatic frequency control contain an primary electrical circuit converting the alternating current into a immediate current, after that converting it back into an alternating current with the mandatory frequency. Internal energy loss in the automated frequency control is rated ~3.5%
Variable-frequency drives are trusted on pumps and machine tool drives, compressors and in ventilations systems for huge buildings. Variable-frequency motors on supporters save energy by permitting the volume of air flow moved to complement the system demand.
Reasons for employing automated frequency control can both be linked to the efficiency of the application form and for conserving energy. For example, automatic frequency control is used in pump applications where in fact the flow is certainly matched either to volume 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 swiftness control-also referred to as a adjustable frequency drive, adjustable frequency drive, variable rate drive, adjustable swiftness 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.