A generator set is an autonomous power generation system consisting of an internal combustion engine coupled to an alternator. Correct specification is critical to ensure electrical stability, protection of sensitive loads and operational continuity at construction sites, industries and events.
Generator sets are usually specified in kVA (kilovolt-ampere), which is apparent power. However, the active power available in kW depends on power factor (PF).
Basic formula:
kW = kVA × PF
Example: A 100 kVA generator at 0.8 PF delivers 80 kW of active power.
Choosing the wrong regime reduces service life and may void warranties.
Electric motors require starting current 3 to 7 times nominal current. The generator must support this peak without excessive voltage drop.
Inadequate sizing can cause:
For sensitive loads (IT, medical equipment), generators with low harmonic distortion (THD < 5%) are recommended.
Specific consumption varies with applied load. Diesel engines offer better energy efficiency and durability in intensive applications.
Operating below 30% of nominal load for long periods can cause wet stacking (carbon buildup).
The generator set must be sized based on actual installed load, operating profile and load characteristics. Oversizing increases capital cost; undersizing compromises stability and service life. Specification must be technical, based on electrical engineering and demand analysis.
