Motor Efficiency Loss
Motor Efficiency Loss
(OP)
Hi All,
We have a 460 V, 100 HP compressor motor that is running at about 50% of rated load. What kind of efficiency losses are typical when running at this low of a load?
Please let me know if you need more information.
Thanks.
We have a 460 V, 100 HP compressor motor that is running at about 50% of rated load. What kind of efficiency losses are typical when running at this low of a load?
Please let me know if you need more information.
Thanks.






RE: Motor Efficiency Loss
RE: Motor Efficiency Loss
Seems like max efficiency in this size range generally occurs around 3/4 load.
RE: Motor Efficiency Loss
It is very useful.
RE: Motor Efficiency Loss
RE: Motor Efficiency Loss
respectfully
RE: Motor Efficiency Loss
RE: Motor Efficiency Loss
Efficiency if defined in terms of real power, but in the end most of us don't just want efficient use of watts, but efficient use of money. You must consider pf penalties to get there.
RE: Motor Efficiency Loss
Compressor motors (as this case is) are sized based upon the worst anticipated operating conditions where they may not always run at these conditions. I have attached another paper on motor efficiencies. Take a look at Figure 3 which gives motor power factor versus loading.
Again to summarize, do not intentionally oversize motors but if the motor loading is 50% or over then you will most likely find a better way to spend your money. EEtheEE should make certain that he measured loading in kW not in amps although this paper indicates about 50% amps at 50% load.
RE: Motor Efficiency Loss
RE: Motor Efficiency Loss
Attached is a section from a Siemens standard motor catalogue (M11) indicating efficiency and PF at full, 3/4,1/2,1/4 and also 5/4 load. It should give some indication as a guide for others.