Completed installation. The entire retrofit took less than a day.
Click here to enlarge imageAt the Rock Creek facility, a MagnaDrive ASD was installed on one of two 60 hp motors and pumps supplying digester biosolids to four belt presses where they are pressed and de-watered. The system was previously controlled with variable frequency drives. Surprised engineers and operators watched as all four presses were brought online with only one pump, negating the need for a second pumping system and the associated equipment and space. Vibration and shaking experienced with the VFD-controlled system were eliminated.
Energy audit data showed less than 10 hp needed to supply full flow to four presses, allowing the motor and the MagnaDrive ASD to be subsequently downsized from 60 hp at 1800 rpm to 20 hp at 1200 rpm. This reduced energy demand from 9.6 kW draw for two 60 hp motors running on VFDs, to 5.5 kW draw for one 20 hp motor running the pump through the MagnaDrive ASD - a reduction of nearly 28 percent. In addition, closing the bypass valve that had been continually open demonstrated an additional 23 percent decrease in energy use.
Over time, the magnetic ASD significantly reduced maintenance and replacement costs and avoided the commonly cited problems of VFDs, including harmonics, noise, heat and space limitations. The motor size reduction was another key benefit, as engineers were given the freedom to control the load with a motor sized for running - rather than start-up. WW/
About the Author: Ken Black, PE, is Senior Applications Engineer for MagnaDrive Corporation. To learn more about this new technology, contact Black at 206.694.4731