PRELIMINARY ENGINEERING TOOL
Third-harmonic neutral-current worksheet
Illustrate equal, coherent third-harmonic addition using measured harmonic components—not total phase current.
Inputs
Calculation steps
I_N,3 = 3 × 20 A = 60.00 A; I_phase,RMS = √(100² + 20²) = 101.98 A
Formula ID: NEUTRAL_EQUAL_THIRD_HARMONIC_V1
- fundamentalCurrentA
- 100
- thirdHarmonicCurrentA
- 20
- thirdHarmonicNeutralA
- 60
- phaseRmsCurrentA
- 101.98039
- thirdHarmonicPctOfFundamental
- 20
Intermediate values are retained without display rounding in the calculation.
Assumptions and references
All three phases must have the same third-harmonic RMS magnitude and phase coherence. The two entered currents are spectral components from the same operating condition. The result is neither total neutral current nor a conductor-sizing value.
How to read the measured harmonic value →UNDERSTAND THE TOOL
What this calculator does
Illustrate addition of equal third-harmonic components in a three-phase four-wire system. It does not infer harmonics from total phase current.
How to use it
- Obtain a power-quality measurement of fundamental and third-harmonic RMS current.
- Use values from the same operating condition and confirm equal phase components are a supportable assumption.
- Review the third-harmonic neutral component and phase RMS result.
- Measure the actual neutral and review the full harmonic spectrum separately.
Fields and meanings
- Fundamental phase current
- RMS current of the 50/60 Hz fundamental on each phase for this equal-phase example.
- Third-harmonic phase current
- RMS current at the third harmonic on each phase—not total RMS or THD percentage.
Review required. Review required. Unequal components, other harmonics and neutral-conductor sizing are outside this worksheet.
Read the full explanation →