Harmonic Filter Calculator
Calculate the tuning capacitor and inductor values for a single-tuned passive harmonic filter.
Tuning Frequency
300 Hz
Tuning Frequency vs Fundamental Frequency
Formule
## Single-Tuned Harmonic Filter Design A series LC filter tuned to a specific harmonic frequency provides a low-impedance path that diverts harmonic current away from the system. ### Design Steps 1. **Capacitive reactance at fundamental**: Xc = V^2 / kVAR 2. **Inductive reactance at fundamental**: Xl = Xc / n^2 3. **Capacitance**: C = 1 / (omega x Xc) 4. **Inductance**: L = Xl / omega Where n is the harmonic order and omega = 2 x pi x f_fundamental. Filters are typically tuned slightly below the target harmonic (e.g., 4.7th instead of 5th) to avoid resonance with system impedance.
Exemple Résolu
5th harmonic filter, 50 kVAR, 480 V, 60 Hz system.
- 01Tuning frequency: 60 x 5 = 300 Hz
- 02Xc at 60 Hz: 480^2 / 50000 = 4.608 ohms
- 03Xl at 60 Hz: 4.608 / 25 = 0.184 ohms
- 04C = 1 / (377 x 4.608) = 575.7 microfarads
- 05L = 0.184 / 377 = 0.49 mH
Questions Fréquentes
Why tune below the exact harmonic?
Component tolerances and temperature variations can shift the tuning point. Detuning slightly low prevents dangerous parallel resonance.
How many harmonics need filters?
The 5th and 7th are typically the largest for 6-pulse drives. The 11th and 13th may also need filtering for 12-pulse systems.
Can one filter handle multiple harmonics?
A single-tuned filter targets one harmonic. For multiple harmonics, use multiple filter branches or a broadband (high-pass) filter.
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