By Alan Wharton
Technology improvements have made Variable Frequency Drives (VFDs) a more reliable and cost effective method of speed control. With the advancements of VFDs in recent years, they have evolved into highly sophisticated digital microprocessor controllers and high frequency power devices.
Now that VFDs have become so accepted in the industrial market, the potential for retrofits and new project installations remain very high. Demand for energy savings and process control will continue to provide double-digit growth for many years to come—and the two most common applications for maximum energy savings remains in centrifugal pumps and fans. With the recent requirements to reduce the overall demand on the power grid, there are many utility companies providing rebates and cost-sharing programs that, in some cases, will provide product at virtually no cost to the user.
History has shown that although you can achieve two to six percent energy savings with premium efficient motors over standard efficient (EPACT) motors, VFDs can provide up to 35 percent savings if applied properly. In many cases pumps and fans are sized according to worst-case-scenario using maximum flow conditions or by using a “rule of thumb” approach to apply a 20 percent oversizing formula. It is important to evaluate the complete application and system characteristics to determine the potential savings available.
In addition to energy savings, other benefits include the reduction and/or elimination of motor starters, less stress on the motor windings and bearings, and a decrease in stress and wear on the pump or fan itself. Taking all of this into consideration will equate to a smoother, longer lasting, more controllable and more efficient operation process.
Please contact OTP Industrial Solutions to receive technical assistance on how to apply VFDs to your application or to evaluate your process to determine potential energy and cost savings opportunities.