Phase Academy

Harmonics & Waveform Distortion Lab

Build distorted waveforms by mixing harmonic orders 3 through 13, measure THD and K-factor in real time, and explore how VFDs, rectifiers, LED drivers, and office electronics each create distinct harmonic signatures.

READYINTERMEDIATEIEEE
FOURIER • H3–H13IEEE 519 VALIDATIONK-FACTOR MODELLIVE THD CALC
Launch lab

Overview

Most electrical engineers have heard of harmonics but few can intuitively predict how a specific mix of 3rd, 5th, 7th, 9th, 11th, and 13th harmonic components will distort a waveform, stress the neutral conductor, heat a transformer, or violate IEEE 519 limits. This lab makes all of that visible: drag harmonic-order sliders to add or remove components and watch the composite waveform, THD calculation, and frequency spectrum update in real time. Six presets represent real-world load profiles — Clean Sine, Mild Nonlinear, VFD Industrial, Triplen-Heavy Office, Severe Distortion, and Neutral Stress. The Spectrum tab shows the harmonic bar chart with individual order magnitudes. The Neutral tab models triplen-harmonic addition in a 4-wire system, showing how 3rd-harmonic current from single-phase nonlinear loads adds in the neutral instead of canceling. The Validation tab checks results against IEEE 519 voltage and current distortion limits. Fundamental frequency is selectable at 50 or 60 Hz and load profile affects which limit table applies. K-factor is computed for transformer selection.

App preview

A live look at the app you'll launch — every control on the left drives the visualizations on the right in real time.

Inside the lab

Overview — orients you to what the lab teaches: how individual harmonic orders combine into a distorted waveform, how THD and K-factor are computed, and where IEEE 519 limits come from. Start here to see the roadmap of tabs (Waveform, Spectrum, Neutral, Scenarios, Design Check, Learn) before dropping into the interactive tools.
Waveform Lab — drag sliders for the 3rd, 5th, 7th, 9th, 11th, and 13th harmonic orders and watch the composite time-domain waveform, RMS, crest factor, and live THD update. Toggle 50/60 Hz fundamental and load one of six presets (Clean Sine, Mild Nonlinear, VFD Industrial, Triplen-Heavy Office, Severe Distortion, Neutral Stress) to see how each real-world load type shapes the wave.
Harmonic Spectrum — the same waveform decomposed into the frequency domain as a harmonic bar chart. Each bar is one order's magnitude as a percent of the fundamental, which is exactly what a power quality meter reports. Use it to build intuition for reading a real PQ report and to see why VFDs emphasize 5th/7th while single-phase electronics emphasize triplens.
Neutral / System Impact — models a 4-wire wye system and shows how 3rd/9th/15th (triplen) harmonic currents from single-phase nonlinear loads add in the neutral rather than cancel. Neutral current can exceed phase current, which is the classic office-building overload story. K-factor is shown alongside so you can size a K-rated transformer for the same spectrum.
Scenario Lab — one-click preset load profiles that jump the sliders to representative spectra: 6-pulse VFD, triplen-heavy office, severe distortion, and neutral-stress cases. Great for guided walkthroughs — pick a scenario, then hop to Waveform, Spectrum, and Neutral tabs to compare how each preset looks in every view.
Design Check — validates the current spectrum against IEEE 519 voltage and current distortion limits. It picks the correct limit row based on the load profile and flags individual-harmonic and total-demand-distortion violations, so students see exactly which order pushed the system out of compliance.
Learn Mode — the reference material behind every tab: Fourier decomposition, THD math, K-factor formula, why triplens add in the neutral, and how IEEE 519 buckets loads by short-circuit ratio. Use it as a mini-textbook students can flip back to while experimenting.

What you'll do

  • 01Explain Fourier decomposition and how any periodic waveform can be expressed as a sum of harmonic components
  • 02Predict which harmonic orders a VFD, rectifier, LED driver, and office electronics mix will emphasize
  • 03Calculate THD from individual harmonic magnitudes and relate it to IEEE 519 current and voltage limits
  • 04Explain why triplen harmonics (3rd, 9th, 15th) add rather than cancel in the neutral of a 4-wire system
  • 05Select a K-factor transformer rating given a known harmonic spectrum from a mixed load
  • 06Interpret a frequency spectrum (harmonic bar chart) from a power quality measurement report

Who it's for

EngineerStudentInstructorTechnician

Tags

HARMONICSTHDTOTAL HARMONIC DISTORTIONK-FACTORIEEE 519WAVEFORM DISTORTIONFOURIER3RD HARMONICTRIPLENNEUTRAL OVERLOADVFD HARMONICSRECTIFIERNONLINEAR LOADFREQUENCY SPECTRUMPOWER QUALITY
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