Adjustable frequency drives arealso known as adjustable speed drives, variable frequency drives, variable speed drives, VFDs andinverters.
Adjustable frequency drives are solid state electric motor control systems designed to control the speed of an electric motor. Adjustable frequency drives can reduce energy costsup to 50% by speed reduction on electric motorswhere the full speed of the electric motor is not needed. Drivefunctions allow an AC electric motor to only operate when neededwhich allows an electric motor to last longer.Technology has allowed adjustable frequency drives to reduce in cost and physical size and has improved performance through advances in semiconductor switching devices, simulation, control techniques, control hardware, and software.
Approximately one third of electrical energy in the world is supplied by electric motors in fixed-speed centrifugal pump, fan, and air compressor applications. These fixed-speed applications do not usually require full load speed of the electric motor theyre operating. By installing adjustable frequency drives to these applications, electric motor speeds are reduced and power costs can be reduced by 50% or more.Properly applied adjustable frequency drives withelectric motorswill significantly reduce energycosts for variable torque loads such as fans, blowers, and pumps.Blowers are often used with dampers to control air flow that operate either manually or automatically. When dampers are closed, 50% of the electric motor current will drop to approximately 60% of full load nameplate current. By utilizing adjustable frequency drivesin blower applications, the current draw of the motor will be reduced 30% for every 10% drop in speed. Electric motors controlled byadjustable frequency drives at 50% speed will draw approximately 20% of the electric motor full load current.
Adjustable frequency drives are also used on rotating equipment toreduce amperage spikes upon start up of large electric motors.Adjusting the acceleration and deceleration time of electric motors can extend the lifespan of an electric motor. Using a drive on an electric motor provides the ability to increase or decrease the frequent starting and stopping of an AC electric motor. Limiting the starting and stopping of a motor and controlling the ramp up and ramp down speed of amotor allows for decreased wear on an electric motor.Choosing the right drive for an application can helprotating equipment by providing less wear on the electric motors where applied.Adjustable frequency drivesare used in AC servo systems, air compressors, conveyor systems, lathes, mills, plastic extrusion, slitter lines, bottlers, packaging lines, pharmaceutical production, food processing, HVAC systems, waste water treatment systems, submersible pumps, fans, blowers, and many more electric motor applications.