VARIABLE SPEED DRIVE GUIDES
These articles will help you understand how to use variable speed drives on pumps and when.
This book "Variable Speed Pumping, a guide to successful applications" by the Hydraulic Institute is excellent. This version is a summary of the book that is made freely available by The Hydraulic Institute on the web. The full version of the book is available on their web site www.pumps.org.
Another good book "Variable Speed Driven Pumps, best practice guide" by the British Pump Manufacturers Association (BPMA) is also made available freely on the web. You can visit their web site at www.bpma.org.uk.
Also see articles on variable speed on this web page: pumpworld.htm