Reduce Energy Costs Up To 60% Using A Variable Frequency Drive (VFD)
Tuesday, November 11, 2008 13:01A properly applied Variable Frequency Drive (VFD) will significantly reduce operating costs. This is particularly true for variable torque loads such as:
- Fans
- Blowers
- Pumps
Blowers, for example, are often used with dampers to control air flow. These dampers may be operated either manually or automatically. When dampers are closed, 50% motor current will drop to approximately 60% of Full Load nameplate current. By utilizing a Variable Frequency Drive (VFD) in this application, current draw in the motor will be reduced 30% for every 10% drop in speed. The same motor operating from a Variable Frequency Drive (VFD) at 50% speed will draw approximately 20% of FLA.
An example application:
A 10 HP AC motor rated 90% efficient running across the line with the dampers operating between 50 – 70% for 2000 hours per year will require 11,996 KWH. If your KWH charge is $.08 per KWH, the cost to run this motor will be: $1,248.00 annually.
The same motor operating from an ASD between 50 – 70% speed for 2000 per year will require 4,676 KWH. Operating cost at the same KWH rate will be: $ 432.00 per year. This represents a savings of $ 816.00 per year and should be enough to pay for the investment into a drive and installation costs in the first 12 months of operation.
If the application operates more hours than in this example and/or the KWH charge is higher the savings will compound very fast.
Reduce Energy Costs Up To 60% Using a Variable Frequency Drive
Another factor to consider is mechanical wear. Because the motor and blower in this application is running at a lower speed mechanical wear will be proportionally less. You should also expect less vibration and heat that may affect other equipment nearby.
Most VFD’s will accept a 4-20 Ma input signal for speed reference and control. Most pressure transducers and automatic controllers can be wired directly into the same control position as your automatic damper. (also 4 – 20 ma)
The same theory will apply to all variable torque loads. A variable torque load is one that the load on the motor shaft increases when speed increases, or decreases when the speed decreases.
Joe Chamberlin
http://www.vfddistributing.com
Our Company offers Energy Reduction Analysis Services to Customers seeking to reduce their overall energy consumption. Feel free to contact us if you wish to have us calculate the possible savings you may receive from utilizing the energy efficiency of Variable Frequency Drives.
Have Questions about Variable Frequency Drives? Feel Free to Leave a Comment for this Post or Contact Us through our Website at http://www.vfddistributing.com/. Interested in Purchasing a Variable Frequency Drive for your Application?
