- High horsepower (greater than 15 to 30 hp)—the higher the pump horsepower, the more cost-effective the ASD application.
- Load type—Centrifugal loads with variable-torque requirements (such as centrifugal pumps or fans) have the greatest potential for energy savings. ASDs can be cost-effective on positive displacement pumps, but the savings will generally not be as great as with centrifugal loads.
- Operating hours—In general, ASDs are cost-effective only on pumps that operate for at least 2,000 hours per year at average utility rates.
- High utility rates—higher utility energy charges provide a more rapid payback on an investment in an ASD.
- Availability of efficiency incentives—where they are available, electric utility incentives for reducing energy use or installing energy-saving technologies will reduce payback periods.
- Low static head—ASDs are ideal for circulating pumping systems in which the system curve is defined by dynamic or friction head losses. They can also be effective in static-dominated systems—but only when the pump is carefully selected. A thorough understanding of pump and system interactions is critical for such applications.
July 26, 2007
ASDs are ideally suited for variable-torque loads from centrifugal pumps, fans, and blowers when the system load requirements (head, flow, or both) vary with time. Conditions that tend to make ASDs cost-effective include the following: