These motors are created for the application form requirements of variable quickness drive systems. You can expect both the following types of motors:
• Constant Torque: Motors specifically designed to handle continuous 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 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 effect of these voltages is definitely an increase of up to 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 will need 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 must have got a du/dt filter.
If the cable duration between the drive and electric motor is higher than 150 meters and the voltage is between 600 and 690 V, the motor will need to have reinforced winding insulation.
A variable-frequency 
drive is something for controlling the rotational swiftness of an alternating current electric electric motor. It regulates the frequency of the electrical power supplied to the electric motor. A adjustable frequency drive is a specific kind of adjustable-swiftness drive. Variable-frequency drives are also known as adjustable-frequency drives (AFD), variable-velocity drives (VSD), AC drives, or inverter drives.
Automatic frequency control contain an primary electrical circuit converting the alternating current into a direct current, then converting it back to an alternating current with the mandatory frequency. Internal energy loss 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 huge buildings. Variable-frequency motors on followers save energy by Variable Drive Motor permitting the volume of atmosphere moved to complement the system demand.
Reasons for employing automatic frequency control may both be related to the functionality of the application form and for conserving energy. For instance, automatic frequency control is utilized in pump applications where the flow is definitely matched either to volume or pressure. The pump adjusts its revolutions to a given setpoint with a regulating loop. Adjusting the circulation or pressure to the actual demand reduces power usage.
An AC motor swiftness control-also referred to as a variable frequency drive, adjustable frequency drive, variable acceleration drive, adjustable speed drive and AC inverter-is an electro-mechanical object that can be utilized to improve the output speed of an AC motor by adjusting the insight frequency into the motor.