What is the kva for 7.5 hp 3 phase motor for 1 hour?

Answer 1

1 hp is generally around 750 watts, so you can expect a 7.5hp motor at full load to be ~5.6kW.

If lightly loaded, the motor will draw less current, thus less wattage. Also, you cannot calculate current directly from the kW rating and voltage (so full load current will not be 5600/230 = 24.3Amps), as motors are not 100% efficient, and do not have 1.0 power factor. I'd expect the full load amperes to be greater than the kw/voltage value by 20-30%.

I looked up a Baldor motor stated to be 7.5hp, and it was ~7kVA, 5.6kW at full load.

Another Answer

You don't specify whether you want to know the machine's output power or its input power.

The rated power of a motor is always its output power. In North America, this is expressed in horsepower whereas, in the rest of the world, this is expressed in watts (in practice, kilowatts). As 746 W is equivalent to 1 horsepower, then a 7.5 horsepower motor is equivalent to 5.6 kW.

If you wish to determine the rated input power to a machine, which is always larger than its output power, then you must know its efficiency at its rated output power. Divide the output power by the efficienty (expressed as a per unit value).

Answer 2

7.5 horsepower is the machine's output power; without knowing its efficiency, you cannot determine its input (true) power.

To determine its apparent power, you will need to know its input power and its power factor.