kVA (Kilovolt-Ampere)

kVA (kilovolt-ampere) is the unit of apparent power, equal to 1,000 volt-amperes. In a single-phase circuit apparent power is voltage multiplied by current; in a balanced three-phase circuit it is √3 multiplied by line voltage and line current. Apparent power combines real power (kW) and reactive power (kvar), and real power equals kVA multiplied by power factor. Transformers, generators and UPS systems are rated in kVA because their heating, and therefore their capacity limit, depends on voltage and current regardless of the load power factor. For example, a generator rated 500 kVA at 0.8 power factor can deliver up to 400 kW. When specifying equipment, the load in kW, the expected power factor, and any motor starting or harmonic currents should all be considered to avoid undersizing.

Examples

• 1,000 kVA distribution transformer rating
• 500 kVA standby generator set at 0.8 power factor
• 60 kVA UPS for a control room

Related terms

Generator A generator converts mechanical energy into electrical energy by electromagnetic induction. In an industrial generating … Power Factor Power factor is the ratio of real power (kW), which performs useful work, to the apparent power (kVA) drawn by an AC loa… Transformer A transformer is a static electrical machine that transfers AC energy between two or more windings by electromagnetic in…

← Back to Glossary