Total Harmonic Distortion Calculation Formula

THD Formula:

\[ THD = \frac{\sqrt{\sum_{h=2}^{n} (harmonic_h)^2}}{fundamental} \times 100\% \]

Total Harmonic Distortion (THD):

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1. What is Total Harmonic Distortion?

Total Harmonic Distortion (THD) is a measurement of the harmonic distortion present in a signal, defined as the ratio of the sum of the powers of all harmonic components to the power of the fundamental frequency.

2. How Does the Calculator Work?

The calculator uses the THD formula:

\[ THD = \frac{\sqrt{\sum_{h=2}^{n} (harmonic_h)^2}}{fundamental} \times 100\% \]

Where:

\( harmonic_h \) — Amplitude of the h-th harmonic
\( fundamental \) — Amplitude of the fundamental frequency

Explanation: The equation calculates the square root of the sum of squares of all harmonic components divided by the fundamental frequency, expressed as a percentage.

3. Importance of THD Calculation

Details: THD is crucial in power systems and audio electronics to quantify how much distortion a waveform has undergone. Lower THD means better signal fidelity.

4. Using the Calculator

Tips: Enter the fundamental frequency amplitude and comma-separated harmonic amplitudes (all in volts or amps). The fundamental must be greater than zero.

5. Frequently Asked Questions (FAQ)

Q1: What is considered a good THD value?
A: For audio systems, THD below 1% is generally inaudible. Power systems often aim for THD below 5%.

Q2: How many harmonics should I include?
A: Typically up to the 20th harmonic is sufficient, as higher harmonics have diminishing effects.

Q3: What's the difference between THD and THD+N?
A: THD+N includes both harmonic distortion and noise, while THD only considers harmonic distortion.

Q4: Can THD be greater than 100%?
A: Yes, if the harmonics are very strong compared to the fundamental, THD can exceed 100%.

Q5: How does THD affect power systems?
A: High THD can cause overheating, equipment malfunctions, and interference with communication systems.