Electrical Gurus - How to calculate motor amperage

[BassBomb]

I have motor/fan information (Horsepower, RPM, Voltage, Phase, Hz)... How can I determine the running amperage based on these parameters?

 

[Canun]

There used to be a conversion chart for household voltages and horsepower. Been out of that game for a long time though, and don't remember otherwise.

 

[Fiat1]

(single phase) locked rotor current = HP x KVAhp (code letter)x1000 /voltage

(3 phase) Locked rotor current = hp x KVAhp (code letter) x 1000/ voltage x 1.73

Or NEC motor tables 430 XIV

 

[BoomerD]

Probably too many variables to get an exact amperage, but there are calculators that should get you close...or get an average amperage for a motor type.

http://www.shipcopumps.com/MathWizard/mw_motoramperage.asp

http://www.cerusind.com/amperagecalc.asp

http://www.veris.com/calculator.aspx

I know there are actual formulas that these are based on...

http://www.elec-toolbox.com/Formulas/Motor/mtrform.htm

http://www.sawmillcreek.org/showthread.php?6316-Formula-for-converting-HP-to-AMPs-or-Visa-Versa

http://answers.yahoo.com/question/index?qid=20070928193543AAhM6GU