Alternating Current
Total Harmonic Distortion Calculator
This page handles the arithmetic for total harmonic distortion while leaving room to review units, limits, and source conditions.
Check Total harmonic distortion
Small unit changes can move total harmonic distortion; confirm scale before using the result.
What total harmonic distortion means here
This worksheet is for calculate thd from combined harmonic rms. The answer is easier to trust when the entered values describe the same equipment, period, and operating condition.
On Total Harmonic Distortion, keep the waveform basis visible: RMS, peak, frequency, and phase terms are not interchangeable.
If two cases differ in rms of harmonic components, save them as separate runs. A blended entry can hide the reason the total harmonic distortion changed.
Fundamental RMS value and the other entries
On Total Harmonic Distortion, confirm decimal placement and unit scale before using total harmonic distortion; small prefixes can move an electrical result by orders of magnitude.
- RMS of harmonic components. Example value: 12 V. Enter RMS of harmonic components in V.
- Fundamental RMS value. Example value: 230 V. Enter fundamental RMS value in V.
A separate Capacitive Reactance run is cleaner when that result becomes the real design question.
The Total Harmonic Distortion equation
The Total harmonic distortion value and any supporting metrics belong to this same Total Harmonic Distortion case, not to a nearby run with different inputs.
Read the Total Harmonic Distortion equation from the units on this page. A familiar symbol can shift meaning between DC, AC, energy, component, or billing work.
A clean Total Harmonic Distortion result confirms the arithmetic for total harmonic distortion; it does not prove the equipment rating or source data is the right one.
Sample Total Harmonic Distortion run
Using the sample values, RMS of harmonic components = 12 V; Fundamental RMS value = 230 V, the primary result is 5.22%.
This Total Harmonic Distortion one-input test is a scale check, showing direction and sensitivity without turning the changed case into a recommendation.
If the changed rms of harmonic components comes from a real measurement, keep the original Total Harmonic Distortion run so the source of the difference remains clear.
Turning total harmonic distortion into a decision
Use total harmonic distortion as a checkpoint. If it drives a decision, compare a conservative Total Harmonic Distortion case before accepting the number.
On Total Harmonic Distortion, keep the waveform basis visible: RMS, peak, frequency, and phase terms are not interchangeable.
Changing rms of harmonic components while leaving fundamental rms value fixed is a useful way to see which assumption controls the answer.
What not to assume from Total Harmonic Distortion
The harmonic input must exclude the fundamental component.
- Distorted waveforms
- Phase reference mistakes
- Three-phase connection assumptions
When total harmonic distortion is close to a rating, use the stricter review path instead of relying on the extra decimals shown by Total Harmonic Distortion.
Notes to save with Total Harmonic Distortion
Save the Total Harmonic Distortion waveform reference, meter mode, and whether the values are RMS or peak.
| Input set | RMS of harmonic components, and Fundamental RMS value |
|---|---|
| Result | Total harmonic distortion |
| Condition note | The harmonic input must exclude the fundamental component. |
Common Total Harmonic Distortion questions
Can the default values be used as a recommendation?
No. The Total Harmonic Distortion defaults only demonstrate the form. Replace them with measured or rated values for the actual alternating current case.
Which value should be rounded first?
Keep rms of harmonic components at source precision during Total Harmonic Distortion; round total harmonic distortion only where presentation or purchasing requires it.
Should nameplate and measured values be mixed?
Only mix nameplate and measured values in Total Harmonic Distortion when that mix represents the actual case. Otherwise keep them in separate runs.