Choosing the right diesel generator set is not just about total power (kW/kVA). If key load factors are ignored, it can lead to voltage instability, overheating, or generator failure.
This quick guide helps buyers understand how to correctly calculate and match generator load.
Check Your Load Type (Very Important)
Normal loads (easy to handle):
Lighting, heaters, standard motors
Sensitive / nonlinear loads:
UPS systems, battery chargers, LED lighting, inverters
👉 These devices generate harmonics, which can:
- Distort voltage
- Increase generator temperature
- Reduce lifespan
Recommendation:
Choose a diesel generator with stable output (AVR) or increase capacity margin by 10–30%.
Consider Motor Starting Current
Motors require 2–7 times their rated current at startup.
👉 If ignored, it may cause:
- Voltage drop
- Generator shutdown
Best practice:
- Start large motors one by one
- Use soft starters or VFDs
Balance Three-Phase Loads
For 3 phase diesel generators, load balance is critical.
👉 Unbalanced load can cause:
- Voltage fluctuation
- Equipment damage
- Motor overheating
Rule:
Keep voltage imbalance within 2% and distribute loads evenly across phases.
Pay Attention to Power Factor
Most generators are designed for lagging power factor (inductive loads).
However, long cables or special systems may create leading power factor (capacitive loads).
👉 Result:
- Unstable voltage
- Reduced efficiency
Solution:
Add reactors or compensation devices if needed.
Harmonics from Electronic Equipment
If your project includes:
- UPS systems
- Battery chargers
- LED lighting
- Variable frequency drives (VFDs)
👉 Harmonics will:
- Increase heating
- Cause waveform distortion
- Raise neutral current
Recommendation:
Use 2/3 pitch winding generators or oversize capacity.
Avoid Running at Full Load Continuously
Running a generator at 100% load for long periods will:
- Increase temperature
- Shorten service life
- Raise failure risk
👉 Ideal load range: 70%–80% of rated capacity
Ensure Voltage Stability for Sensitive Equipment
For industries like:
- Data centers
- Hospitals
- Telecom
👉 Stable voltage is critical
Recommendation:
Choose generators equipped with:
- AVR (Automatic Voltage Regulator)
- Fast transient response
In real-world projects, generator load is rarely simple. Factors like nonlinear loads, motor starting, and phase balance can significantly affect performance.Choosing the right diesel generator is not just about power-it's about matching your actual working conditions.
