Power Calculations & Formulas
Below is a quick reference guide of some power calculations and formulas. If you have any questions about computing your power needs, do not hesitate to give us a call or send us an email.
Power Factor (P.F.) Formula
Single Phase |
Three Phase |
kW / kVA |
kW / kVA |
kW Formula
Single Phase |
Three Phase |
(Volts x Amps x P.F.) / 1000 Or kVA x P.F. |
(1.73 x Volts x Amps x P.F.) / 1000 or kVA x P.F. |
kVA Formula
Single Phase |
Three Phase |
(Volts x Amps) / 1000 Or kW / P.F. |
(1.73 x Volts x Amps) / 1000 or kW / P.F. |
Amperes – When kW is Known Formula
Single Phase |
Three Phase |
(kW x 1000) / (Volts x P.F.) |
(kW x 1000) / (1.73 x Volts x P.F.) |
Amperes – When kVA is Known Formula
Single Phase |
Three Phase |
(kVA x 1000) / Volts |
(kVA x 1000) / (1.73 x Volts) |
Required Prime Mover Horse Power Formula
kW / (Alternator Efficiency x 0.746) |
Frequency (Hertz) Formula
(Number of Poles x R.P.M.) / 120 |
Revolutions Per Minute (R.P.M.)
(Hertz x 120) / Number of Poles |
Voltage Regulation (in%) Formula
(No Load Voltage – Full Load Voltage x 100) / Full Load Voltage |
Speed Regulations (in%) Formula
(No Load R.P.M. – Full Load R.P.M. x 100) / Full Load R.P.M. |
Voltage Dip Factor (Motor Starting) Formula
(100% - Voltage Dip%) / 100 |