In most pump applications, motors do not need to run at full throttle to get the job done. Yaskawa's Michelle Bartlelson reminds us that, on average, these motors can meet demand by running at just 70 percent of shaft speed. The additional system capabilities, she writes are usually reserved to accommodate future expansions or infrequent increased load demands. And that's where a VFD can help. Various controllers can be used to run a motor at reduced speed.
A VFD can be used to operate a pump motor at any speed, and operating a pump motor below base speed to meet the requested demand can show significant energy savings. There is a whole article about it in Modern Pumping Today magazine.