I would like to know the relative e

[ralft]

I would like to know the relative efficiency of a 5 HP single phase vs. a 3 phase induction motor. The application is an air conditioning compressor (hermetically sealed motor). The same question would apply to a quirrel cage fan motor 1 HP.

 

[electricpete]

Generally the three phase will be more efficient.

Pick out specific motors of interest and see for yourself:

http://www.reliance.com/cgi-bin/mtrquery.pl#modelchar

 

[ralft]

Thanks for the reference but I couldn't find any info on 1 phase motor efficiency. Instead, they seem to consistently say "single phase motors are not required to meet EPAct efficiencies".

 

[busbar]

Have you tried contacting high-volume consumer-grade OEMs for their take on the matter? Induction motors for hermetic refrigeration would be considered fairly specialized. In the US, try Tecumseh and Copeland.

 

[electricpete]

http://www.reliance.com/pdf/pdf/aced/M8068.pdf

1 horsepower, 1800rpm single phase motor. 72% efficient at full load.

busbar is right that none of the motors in this catalog are hermetic.

 

[jbartos]

Suggestion: Visit

http://www.baldormotors.com

etc. for more info

 

[ralft]

Thanks for the suggestion, jbartos, but I couldn't find any effciency info for single phase motors.