Converting kW to kVA when selecting a generator.
Power ratings can be expressed in many different forms such as kilowatts and watts, amps or amperes, kilovolts and volts, and also in kVA.
Away from the diesel generator industry, the term Kilo-volt-amperes or kVA is not very well known.
Kilowatt or kW is the more common term and is how electrical items in your home and business are rated, it is also the units usually quantified on your electricity bill so it is much more relatable but what is kVA?
We tend to refer to kW as actual power, it is the amount of power that is converted into an output.
We can call the kVA a measure of apparent power: it describes the total amount of power being used by a system.
If a system is 100% efficient system kW would equal kVA exactly. In reality, electrical systems do not work at 100% efficiency and all of the system’s apparent power is not being used for useful work output.
Remember the fundamentals that one kVA is equal to 1,000 volt amps. Whereas a volt is for measurement of electrical pressure an amp is a way of measuring electrical current. A term called apparent power is equal to the product of the volts and amps.
Diesel Generators generally have a power factor of 0.8.
In other words, the actual power is approx. 0.8 of the apparent power.
Whilst there is a slight variation from one generator to another generator, 0.8 is the accepted power factor when calculating actual power output when purchasing diesel generators.
By knowing this it is easy to convert kVA to kW using a power factor of 0.8 as the efficiency level of the electrical system in question.
Electrical efficiency is expressed as a power factor in between 0 and 1, therefore the closer the power factor is to 1, then the more efficiently the kVA is being converted into actual kilowatts.
If you do know your kVA and your kW output you can calculate a precise Power Factor by dividing the kW by the kVA.
pf = kW/kVA
The formula for converting kVA into kW is:
Apparent power (kVA) x power factor (pf) = actual power (kW)
100 kVA x 0.8 = 80 kW
The formula for converting kW into kVA is:
Actual power (kW) / power factor (pf) = apparent power (kVA)
1000 kW /0.8 = 1250 kVa
Use our kW to kVA calculator on our homepage to work out the kVA for the generator you require.
If you know how much kW you need and want to know what kVA you need from a diesel generator:
Use our kVA to kW calculator on our homepage to work out the actual power that you will get from our generators.
If you know the kVA and want to know the expected power output from the generator:
In case you still need help in working out which powered diesel generator is right for you: