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Difference between kW and kVA
In any electric circuit (AC or DC), the electric power is one of the major electrical quantity. The electrical power is broadly classified into three types namely active power, reactive power and apparent power.
These three types of electric powers are measured in different units. Where, the active power is measured in Watts (W), the reactive power is measured in Volt Ampere Reactive (VAR) and the apparent power is measured in Volt Ampere (VA). But in practice, these powers are measured in larger units, i.e., kW (kilo-Watt), kVAR (kilo Volt Ampere Reactive), and kVA (kilo Volt Ampere).
Read through this article to understand how kW is different from kVA. Let's start with some basics of kW and kVA, the relation between kW and kVA, so that it becomes easier to understand the differences between them.
What is kW?
kW is short for kilo Watt. It is the unit of measurement of active power or real power or true power. kW gives the measure of how much average power an electrical device consumes. 1 kW of electric power is equivalent to 1000 watts. Thus, kW can be converted into Watt simply by multiplying the numerical value in kW by 1000, i.e.
$$\mathrm{1\:kW\:=\:1\:\times\:1000\:W\:=\:1000\:W}$$
In DC circuit, the Watt or kW is used to measure the average DC power, whereas in an AC circuit, it is used to measure the active or real part of the total AC electric power.
kW is the unit of power which is used to define the load type electrical devices such as motors, lamps, irons, heaters, etc.
What is kVA?
kVA stands for kilo Volt Ampere. kVA is the unit of measurement of apparent electric power in the AC circuit. kVA is a large unit of apparent power, its base unit is VA (Volt Ampere). kVA is the term which is related to AC circuit only. There is no such thing in a DC circuit, because in a DC circuit, the total power is measured in watts or kW.
Just like kW, kVA may also be converted into VA by multiplying it by 1000, i.e.
$$\mathrm{1\:kVA\:=\:1\:\times\:1000\:VA\:= \:1000\:VA}$$
Generally, kVA is used to represent the rating of such electrical devices that act as source such as alternators, generators, transformers, inverters, etc.
Difference between kW and KVA
Both kW and kVA are the units of measurement of electrical power, but they are different from each other. The major differences between kW and kVA are given in the following table −
| Basis of Difference | kW | kVA |
|---|---|---|
| kW stands for kilo-Watt. | kVA stands for kilo Volt Ampere. | |
| Description | The kW is the unit of measurement of average power in DC circuit and active (or real) power in AC circuits. | kVA is the unit of apparent power in AC circuits. |
| Relevant circuit | kW is term related to both AC and DC circuits. | kVA is only relevant in AC circuits. It is not used in DC circuits. |
| What it is? | kW is the measure of active power consumed by an electrical load. | kVA is the measure of total power delivered by a source (ex. generator) to the load. |
| Dependency on power factor | kW is directly proportional to the load power factor. | kVA is independent of the power factor of load. |
| Expression | kW is given by the following expression, $$\mathrm{kW\:=\:1000\:\times\:V\:\times\:A\:\times\:pf}$$ | kVA is given by the following expression, $$\mathrm{kVA\:= \:1000\:\times\:V\:\times\:A}$$ |
| Uses | kW is used to represent the ratings of electrical load devices such as electric motors, electric heaters, iron, lamps, etc. | kVA is used to represent the rating of electrical source devices such as generators, alternators, inverters, UPS, etc. |
Conclusion
The most significant difference that you should note here is that kW represents the amount of electric power consumed by an electric load, whereas kVA represents the total amount of power supplied by a source to an electrical load.
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