How to Calculate Harmonic Distortion
What is Harmonic Distortion?
Harmonic Distortion Calculator helps contractors and tradespeople accurately size, spec, and estimate materials and systems.
Formula
THD = √(V₂² + V₃² + ...) / V₁ × 100
Step-by-Step Guide
- 1Measure fundamental and harmonic voltages with power quality meter
- 2Apply the formula using your project measurements
- 3Add required safety factors or waste allowances per code
Worked Examples
Input
V1=120V, V3=6V, V5=4V
Result
THD = √(36+16)/120 × 100 = 6.0%
Common Mistakes to Avoid
- ✕Not applying code-required safety factors or derating
- ✕Forgetting to account for waste and cut losses in material estimates
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