Re: Convert volts/amps into kilowatt hours

[don cole]

I have well pump 9 amps 230 volts 3 phase 3 HP

How many kw would it use per hour

[JohnS]

Originally Posted by don cole

I have well pump 9 amps 230 volts 3 phase 3 HP

How many kw would it use per hour

In three phase power, you need to know whether the voltage is specified line-to-line or line-to neutral, and whether the three phase currents are equal. Assuming line to line voltage and equal phase currents,

line to neutral is 230/sqrt(3) V
Power is 3*9 A * 230/sqrt(3) V = 3585 W or about 3.6 kW

For each hour of operation, it will draw 3.6 kWh.

The 9 A may represent starting current and not be a continuous draw. The results above imply fairly low efficiency. 3 HP is 2238 W mechanical power at the shaft, and 2238 W/3585 W is 62.4% efficiency, fairly poor for a 3 phase motor. You may wish to measure line current and see if efficiency is this poor or the 9 A occurs only at starting. At 80% efficiency (pure guess, but reasonable) in continuous operation, the motor should only draw about 2800 W, or barely over 7A running current

[QUOTE=don cole;76070]I have well pump 9 amps 230 volts 3 phase 3 HP

How many kw would it use per hour @3hp 20watts