What is the difference between Power Factor and kVA?
In the world of diesel generators, there are two jargon terms that you will always see: kVA and power factor. If someone asked you what your power needs are, you might have also got asked to quote kVA and power factor details.
If you're not too sure what they mean, or what the difference is between those two terms, don't worry: you are not alone! The purpose of this article is to give you a real understanding of kVA and power factor.
Here is what you need to know:
What is kVA?
You will no doubt be aware that power ratings get expressed in different forms like watts, amps, volts, and so on.
One of those power ratings that often gets used when describing diesel generators is kVA. The term is an abbreviation of "kilo Volt Amperes" in case you wondered!
At home, you will get sent electricity bills measured in kW (kiloWatts). So, if that is the case, why aren't diesel generators measured by kW as well? The answer is simple: kW is a measure of actual power, while kVA is "apparent" power.
Your home will have a meter that counts the electricity consumed, measured in kW. But, kVA is a measure of apparent power output.
A fact about electricity is that power supply systems are never 100% efficient. That is because losses occur through load, heat, conduction, and so on.
What is power factor?
So far, you have an understanding of kVA and kW, and the difference between the two. The other question to answer is this: what is power factor?
In layman's terms, the power factor is the ratio of real power (kW) absorbed by the apparent power (kVA). It's a type of measurement used only on AC systems (as opposed to DC). The power factor only has values between zero and one and measured to one or two decimal places.
A simple way to make sense of power factor is by using a pint of beer as an analogy:
- The pint glass is apparent power (kVA). It is the power getting delivered;
- The beer is active power (kW). It's the energy needed to run things;
- The foam is reactive power (kVAR). In other words, it is wasted energy.
No electrical circuits are 100% efficient. If they were, you wouldn't have any reactive power (i.e., the foam in the pint glass). That's why we need to calculate the power factor in diesel generator systems.
Formulas for calculating kVA and Power Factor
When you need to get the best diesel generator for your needs, it's essential to do some calculations. There are some formulas you can use to figure out the kVA and power factor.
Before you start, it's important to note that diesel generators have a power factor of 0.8.
Formula for calculating kW:
- Apparent power x power factor = actual power;
Formula for calculating kVA:
- Actual power / power factor = apparent power.
By knowing the above power values, you can ensure you get the right diesel generator for your needs.