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I have had the same question for years and years. Unfortunately,
the only motor part load efficiency curves available are for constant speed
motors a various percent loading, where frequency remains constant.
To my knowledge... and this was confirmed by a recent Engineered Systems magazine article (August 2003). In this article, "How to Calculate Motor Efficiency for Variable Speed Centrifugal Pumps" by Burt Rishel, Burt states there are no part load motor efficiency curves available in the industry. I agree with Burt recommendation... they should be developed and would be quite useful. Burt is an elder pump guru who has been around since time began, as is considered by many as an authority on pumping systems. Which is why Burt stated the best one can expect when comparing caclulated part load energy use on a variable speed pump (or fan) to field measured part load results are +/- 10%. If by chance you should come across such curves, I'd certainly be interested in seeing them.
Alec Stevens wrote: Hello, Does anyone know of published research that relates motor efficiency to percent load as well as drive frequency?We have motor curves for efficiency vs. percent load, but these curves all assume a nominal speed that is being maintained as load decreases. What happens to your motor efficiency when you are also changing the drive frequency? Thanks for any leads.Sincerely, Alec Stevens, PE ====================================================== You received this e-mail because you are subscribed to the BLDG-SIM@xxxxxxxx mailing list. To unsubscribe from this mailing list send a blank message to BLDG-SIM-UNSUBSCRIBE@xxxxxxxx |