Three-Phase Neutral Current and Third Harmonics
Estimate modeled neutral RMS current from fundamental phase-current imbalance and aligned triplen (third-harmonic) phase currents.
Result
Formula
Calculation logicFormula definitions and substituted values.
Fundamental Sum Squares
Phase A fundamental current (A RMS) ^ 2 + Phase B fundamental current (A RMS) ^ 2 + Phase C fundamental current (A RMS) ^ 2
Phase A fundamental current (A RMS) ^ 2 + Phase B fundamental current (A RMS) ^ 2 + Phase C fundamental current (A RMS) ^ 2Fundamental Cross Terms
Phase A fundamental current (A RMS) * Phase B fundamental current (A RMS) + Phase B fundamental current (A RMS) * Phase C fundamental current (A RMS) + Phase C fundamental current (A RMS) * Phase A fundamental current (A RMS)
Phase A fundamental current (A RMS) * Phase B fundamental current (A RMS) + Phase B fundamental current (A RMS) * Phase C fundamental current (A RMS) + Phase C fundamental current (A RMS) * Phase A fundamental current (A RMS)Fundamental Radical
max(0, Fundamental Sum Squares - Fundamental Cross Terms)
max(0, Fundamental Sum Squares - Fundamental Cross Terms)Fundamental neutral current (A RMS)
sqrt(Fundamental Radical)
sqrt(Fundamental Radical)Third-harmonic neutral contribution (A RMS)
Phase A third-harmonic current (A RMS) + Phase B third-harmonic current (A RMS) + Phase C third-harmonic current (A RMS)
Phase A third-harmonic current (A RMS) + Phase B third-harmonic current (A RMS) + Phase C third-harmonic current (A RMS)Estimated total neutral RMS current (A)
sqrt(Fundamental neutral current (A RMS) ^ 2 + Third-harmonic neutral contribution (A RMS) ^ 2)
sqrt(Fundamental neutral current (A RMS) ^ 2 + Third-harmonic neutral contribution (A RMS) ^ 2)Before relying on the result
- Estimate neutral current for unequal fundamental phase currents
- Add in-phase third-harmonic currents to a neutral RMS estimate
- Estimate fundamental and third-harmonic contributions to neutral RMS current using measured phase currents.
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