Difference Between kW and kVA in Diesel Generators

When selecting a diesel generator, understanding the difference between kW (kilowatts) and kVA (kilovolt-amperes) is crucial for choosing the right power capacity.

1. kW vs. kVA

• kW (Kilowatts) – Represents real power, the actual usable power that performs work (e.g., running motors, lights, and equipment).

• kVA (Kilovolt-Amperes) – Represents apparent power, the total power supplied by the generator (including both real power and reactive power).

The relationship between kW and kVA is defined by the power factor (PF):

kW=kVA×Power Factor (PF)

Most diesel generators have a power factor of 0.8 (80%), meaning: If a generator is rated at 100 kVA, its real power (kW) is 80 kW.

2. Why Does It Matter for Diesel Generators?

• Equipment Compatibility – Some devices (like motors and transformers) require reactive power, so kVA ratings help determine if a generator can handle the load.

• Generator Sizing – If your equipment needs 100 kW, you’ll need a 125 kVA generator (assuming PF = 0.8).

• Efficiency & Cost – A higher power factor (closer to 1.0) means more efficient power usage, reducing fuel costs.

3. Practical Example

A 150 kVA generator with a 0.8 PF delivers:

150kVA×0.8=120kW of usable power

If your load requires 100 kW, this generator is sufficient. But if you need 130 kW, you'll need a larger unit.

Conclusion

• kW = Actual power used by equipment.

• kVA = Total power the generator can supply.

• Power Factor (PF) determines efficiency (typically 0.8 for diesel generators).
  
  

Always check both kW and kVA ratings when selecting a diesel generator to ensure it meets your power needs efficiently.