Table of Contents
Generator Power Basics
Electrical generators convert mechanical energy into electrical energy through electromagnetic induction. The power output depends on the voltage, current, and power factor. For three-phase generators, the sqrt(3) factor accounts for the phase relationship between the three windings.
Real power (watts) is the usable power that performs actual work. Apparent power (VA) is the total power drawn from the generator, including reactive power needed to maintain magnetic fields in inductive loads like motors. The power factor is the ratio of real to apparent power.
Power Formulas
Generator Sizing Guide
| Application | Typical Size | Phase |
|---|---|---|
| Home backup | 5-20 kW | Single |
| Small business | 20-100 kW | Three |
| Industrial | 100-2000 kW | Three |
| Power plant | 10-1000 MW | Three |
Frequently Asked Questions
Why is power factor important for generators?
A low power factor means the generator must supply more apparent power (current) than necessary for the actual work being done. This increases winding losses, requires larger conductors, and reduces the effective capacity of the generator. Most generators are rated at 0.8 power factor.
What is the difference between kW and kVA?
kW (kilowatts) is real power — the actual energy doing work. kVA (kilovolt-amperes) is apparent power — the total power the generator must be capable of supplying. The relationship is kW = kVA x Power Factor. Generators are often rated in kVA because their capacity is limited by current and voltage, not by the load's power factor.