The link between kilowatts (kW) & kilovolt-amperes (kVA) is essential in electrical engineering, especially when it comes to understanding power in alternating current systems.
Kilowatt (kW): This is a unit of real power, or actual power transformed into practical work. It represents the amount of power required by electrical equipment to complete tasks.
kVA (kilovolt-ampere): This unit quantifies apparent power, which includes both real and reactive power in an electrical system. It represents the entire quantity of power that passes through the system.
The mathematical relationship
The power factor (PF), which measures the efficiency with which electrical power is turned into usable work output, can be used to express the relationship between kW and kVA. The formulations are as follows:
To convert kVA into kW:
KW = KVA X PF
To convert kW into kVA:
KVA = KW/PF
Where: PF varies from 0 to 1; a PF of 1 represents a perfectly efficient system as all apparent power is turned into real power (123).
Power Factor Implications
In alternating current circuits, the voltage & current can be out of phase, impacting the power factor. Since the PF is equal to one, kW will typically be less than kVA.
In DC circuits, the PF is always 1, hence kW equals kVA under these conditions.
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kW measures useful power.
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KVA is a unit of measurement for total power provided.
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