Variable frequency drives (VFDs) can save energy and help you develop a continuous-flow manufacturing process. Benefits include:
• Increased energy savings for pumps and fans
• Improved process control
• Reduced mechanical stress through soft start capability
• Payback periods are often less than a year
Energy savings for pumps and fans
(The systems approach)
In most facilities, centrifugal pumps and fans run at fixed speeds. An automatic valve or some other mechanical means varies fluid flow rates. By using a VFD, motor speeds can be regulated electronically. Adjusting pump or fan speed to a desired flow rate can result in energy savings many times that of the motor alone.
Improved process control
The throughput rates of most industrial processes are functions of many variables. For example, throughput in
rubber extrusion or continuous metal annealing depends on, among others, the material characteristics, the crosssectional area of the material being processed and the temperature of one or more heat zones. If a plant uses constant-speed motors to run conveyors on the line, it either must run without material during the time required to change temperature in a heat zone or produce scrap during this period.
When using a VFD, the time needed to change speed is significantly less than the time it takes to change heat-zone
temperature. By adjusting the material flow continuously to match heat zone conditions, a plant can operate continuously. The results are decreased energy usage and less scrap.
Reduced mechanical stress
Drives reduce mechanical stress on process systems by employing soft starts. Starting a motor without soft start
increases stress on the mechanical system. Belts slip and squeal and chains jump.
Reduced-voltage and –frequency starting decreases this mechanical stress. VFDs vary output voltage along with
output frequency. Output voltage varies with the frequency to control a motor’s torque and speed. Controlling torque
and speed results in a soft start as the motor’s speed accelerates based on a pre-programmed rate. Acceleration
time in most VFDs may be varied from 5 to 360 seconds. In short, a VFD inherently offer soft starts.
Contact your Applied® Account Manager to discuss the variable frequency drive best for your application.