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Electric Motor Efficiency
2

Electric Motor Efficiency

Electric Motor Efficiency

(OP)
What are typical motor efficiencies? or where can I reference this information?  

RE: Electric Motor Efficiency

Depending on what motor you are looking at, effeciencies can vary from as low as 10-15% for a shaded pole motor to as high as 90-95% for some DC motors and brushless DC's.

RE: Electric Motor Efficiency

2
Induction motor efficiency could varies mainly with the motor HP rating and less degree with the type of manufacturing technology that had been used historically

Roughly the efficiency could be suggested in average as follow:
  
Rating                                 Full Load
  (HP)                              % Efficiency

< 5                                       75-80
5-25                                      80-88
25-200                                     86-92
200-1000                              91-93
>1000                                     93-95


The efficiency of modern units could be improved in few percents.

RE: Electric Motor Efficiency

Suggestion to the previous posting: The efficiencies appear to be on the lower side. Is there any reference available?

RE: Electric Motor Efficiency

Dear colleagues:

Per Jbartos suggestion, the average efficient for induction motors presented in the previous thread are supported by the enclosed references:

a- Paul M. Anderson, “ ANALYSIS OF FAULTED POWER SYSTEMS” .IEEE Power Engineering Series, Table 6.3

b- R. Doughty, R. Puckett and D. Brethauer “The Impact of Efficiency on the Economics of New Motor Purchase, Motor Repair and Motor Replacement”, IEEE Transactions on Industry Applications, Vol. 30, No 6, Nov/Dec 1994. (Fig 7.: Energy efficient electric motors systems, Three phase four pole –1955-1993).

The values of reference "a" are in agreement with the values of reference "b" for standard motor manufactured after 1993.

The enclosed values have been reasonably comparable with recent motor data used in power plant and industrial applications. However, any recent or accurate references are welcome.

RE: Electric Motor Efficiency

Suggestion: Without much effort, one can open Baldor Electric Motor catalog, e.g. 501 dated December 19, 1994, page 80 where for example 3HP, 1425 RPM, Cat. No. M3211T-50 has listed efficiency 84% at full load. Page 72 lists three phase 575V motor, 3HP, 1760 RPM, Cat. No. EM3211T-5 with the full-load efficiency of 89.5%. These are just samples for comparisons with the first row stating: HP < 5 ~  % Efficiency 75-80
I see that above posting data on the lower side.
Other motor manufacturer catalogs could be cited.

RE: Electric Motor Efficiency

Jbarto,

I found an other source with the following approximate samples of standard motor efficiency to share with all of you.
                
   Speed:             900 RPM    
____________________________________________________
                              NEMA                    IEEE
HP Range    OLD     EPACT       PREMIUM     481
1-5        72.0-84.0   74.0-85.5  75.5-86.5      -
7.5-25        85.5-89.5    85.5-89.5  86.5-90.2      -
30-200        90.2-94.1    91.0-94.1  91.7-94.5      -
250-500        94.5-             95.4         -
____________________________________________________                            
                
                
   Speed:             3600 RPM    
____________________________________________________
                               NEMA                    IEEE
HP Range    OLD     EPACT       PREMIUM     481
1-5     78.5-85.5  75.5-87.5  75.5-86.5     77.0-88.5
7.5-25   85.5-89.5  88.5-91.0  88.5-91.7     89.5-91.7
30-200   89.5-94.1  91.0-95.0  91.7-95.0     91.7-95.4
250-500       95.4     95.0-95.8    95.4           --    
______________________________________            


RE: Electric Motor Efficiency

cuky - definitely star-worthy.

RE: Electric Motor Efficiency

Thank you Cuky for your posting. I guess the source is confidential. Another, star from me too.

RE: Electric Motor Efficiency

Jbartos and all:

Sorry for the late response in regard the source for motor efficiency. The sources used are all are of public domain as shown below:

Standards:
a-NEMA MG-1  (Tables 12-10,12 &13)  (Hard copy)
b) EPAct : Federal Minimum Standard  
    http://www.usmotors.com/What%27s%20New/news003.htm
    http://www.reliance.com/prodserv/motgen/b7087_5/b7087_5_8.htm#APPENDIX%201
c)IEEE: Std 841-2001for severe duty motors.  (Hard copy)

References:
1- Induction Motor Efficiency Standards-J. Douglas, Univ of Washington
2- Motor efficiency - Oak Ridge National Lab ORNL-TM-13237
3- Energy Efficient Electric Motor - BPA DOE/GO 10096-290
            
 Related sites:

http://www6.dwp.ci.la.ca.us/energyadvisor/EA_35fig.html

http://www.energy.wsu.edu/industry/files/02_029.pdf

http://www.motor.doe.gov

RE: Electric Motor Efficiency

Thank you Cuky for the references that make your posting very valuable.

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