Calculation sequence
Step-by-step method
- Calculate real-power loading from measured kW and rated kW.
- Calculate apparent-power loading and power factor.
- Multiply measured kW by duration and compare with the entered test screen.
CommissioningIntermediateEmergency Power
Generator Load-Test Calculator
Calculate generator real- and apparent-power loading, power factor, and test energy.
Why it matters: A generator test should identify both kW and kVA loading, duration, power factor, and the approved test criterion.
Calculated result
Engineering evaluation
Generator real-power loading (LkW)80 %
- Generator apparent-power loading (LkVA)
- 74.63 %
- Measured power factor (PF)
- 0.857 0–1
- Test-step energy (E)
- 1,200 kWh
Engineering interpretation
The test step represents 80% real-power loading and 74.63% apparent-power loading at power factor 0.8571 for 2 hours. The status compares those values with the entered 80% minimum, 100% maximum real-power loading, and 100% maximum apparent-power loading. Final disposition requires the approved generator test procedure and stable frequency, voltage, temperature, and alarm evidence.
Engineering knowledge center
Understand the calculation—not just the answer
Governing relationships
LkW = Pm/Pr×100
LkVA = Sm/Sr×100
PF = Pm/Sm
E = Pm t
within entered test screen when Lmin ≤ LkW ≤ LkW,max and LkVA ≤ LkVA,max
Current substitution
LkW = 600/750×100 = 80%; LkVA = 700/938×100 = 74.63%; E = 1200 kWh.
Equation legend
Inputs and calculated quantities
- Pr
- Generator real-power rating — kW
- Pm
- Measured real power — kW
- Sr
- Generator apparent-power rating — kVA
- Sm
- Measured apparent power — kVA
- t
- Test-step duration — h
- Lmin
- Entered minimum load — %
- LkW,max
- Entered maximum real-power load — %
- LkVA,max
- Entered maximum apparent-power load — %
- LkW
- Generator real-power loading — %
- LkVA
- Generator apparent-power loading — %
- PF
- Measured power factor — 0–1
- E
- Test-step energy — kWh
Applications
How this calculation is used
Building design
Screen generator utilization under planned test steps.
Construction
Prepare load-bank and integrated-system test records.
Commissioning
Document measured loading and duration against entered requirements.
Quality controls
Assumptions and limitations
Assumptions
- Entered values represent the same stable operating condition.
- Measurements and reference values use consistent units and boundaries.
Limitations
- This is a screening and field-verification tool, not an automatic acceptance decision.
- Project criteria, manufacturer data, governing standards, and measurement uncertainty remain controlling.
Field use
Verification procedure
- Confirm the approved reference values and test boundary.
- Stabilize the system and record calibrated field measurements.
- Review calculation assumptions, uncertainty, and supporting evidence before disposition.
Common engineering mistakes
- Comparing readings taken at different loads, modes, or reference conditions.
- Treating a calculated status as proof of code, contract, or manufacturer compliance.
Technical basis
References and source standards
- NEMA StandardsElectrical equipment terminology, ratings, motor, transformer, and generator performance context; the current applicable standard requires professional review.
- ASHRAE Commissioning ResourcesCommissioning-process context for defining test methods, acceptance criteria, evidence, and owner requirements.
Engineering calculation disclaimer
These engineering tools are provided for educational, preliminary evaluation, field verification, and commissioning support. Results depend on the accuracy of user-entered information and the assumptions stated for each calculation. Every colored status and comparison is a screening indicator only; project criteria, contract requirements, applicable codes, manufacturer instructions, measurement uncertainty, and authorized engineering judgment govern. The tools do not replace project-specific engineering analysis or the judgment of a licensed professional engineer.
Read the full use and limitation statement