The Reliability Files

State-of-the-Art Control: Save Energy As You Maintain Normal Motor Speed

EP Editorial Staff | July 19, 2013


Electric motor efficiency, as stated by the manufacturer, often puts customers and operators at ease assuming that a 70% or higher efficiency DOES NOT waste much energy. What many users don’t realize, however, is that electric motors only achieve the rated efficiency when operated at 100% of rated horsepower.  

Across industrial applications, electric motors operate well below the rated horsepower, with the average motor operating at 63%.  Studies indicate that the most common single-phase electric motors operate at partial loads, often at as little as 35% of rated horsepower, especially in applications such as conveyors and wood- or metalworking. A typical 3/4 horsepower capacitor-start induction-run (CSIR) motor is rated 68% energy-efficient at full load.  Unfortunately, the same CSIR motor operating at 35% of full load is typically only 44% energy-efficient. Therefore, most customers aren’t achieving the rated efficiency. This translates into wasted energy, which is often not understood—but always paid for.

The Dayton® Energy-Saving Soft-Start Motor Controller detects when a motor is not fully loaded and reduces the voltage and current fed to the motor, thus conserving energy while maintaining normal motor speed. This characteristic distinguishes it from traditional soft starters that only save energy at startup and Variable Frequency Drives (VFDs) that reduce motor speed. Its patented phase-angle technology doesn’t significantly reduce the RPM of connected motors, thus making The Dayton® Energy-Saving Soft-Start Motor Controller is ideal for constant-speed variable-torque applications, including conveyors, grinders, granulators, drills, mills, saws and many other motor applications.

0713relfiles3smallReturn On Investment
Tests conducted by Rocky Research, a leader in thermal and energy management design for over 25 years, determined that the Dayton® Energy-Saving Soft-Start Motor Controller can reduce the power consumption of a common 3/4 horsepower CSIR electric motor by up to 40%. It’s important, though, to also take into account the other benefits of the controller when considering the total return on investment.  

When an electric motor is 50% efficient, it means 50% of the electrical power put into the motor becomes mechanical power and the other 50% turns into heat. The Dayton® Energy-Saving Soft-Start Motor Controller keeps a motor’s mechanical output nearly the same, while reducing motor overheating. The reduced level of motor overheating, in turn, results in increased motor life. The soft-start capability of this motor controller reduces mechanical wear on attached and connected equipment by avoiding abrupt starts and associated jerking. The soft-start feature also reduces the current inrush to the motor—something that improves electrical-grid stability.

Finally, a major distinction between the Dayton® Energy-Saving Soft-Start Motor Controller and other soft-starters is that it improves the power factor of the motor any time during run operation. It also provides motor overload protection, which helps prevent damage to the motor and attached equipment. To learn more about the Dayton® Energy-Saving Soft-Start Motor Controller and the many technical and operating-cost benefits it offers, visit MT

Exclusively from Grainger
Lake Forest, IL





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