Harmonics and your PFC system
Harmonics are electrical distortions, generated by modern equipment such as variable frequency drives, that act as silent saboteurs. They compromise the efficiency and lifespan of a power factor correction investment, causing overheating, lowering the power factor and wasting energy. For reliable return, a holistic approach that combines PFC with harmonic mitigation is essential.
- Harmonics are waveform distortions from non-linear loads such as VFDs and LED lighting.
- They lower power factor, overheat equipment, waste energy and can trigger dangerous resonance.
- Standard PFC capacitors can resonate with harmonics, amplifying the problem.
- For reliable savings, combine power factor correction with harmonic mitigation.
Power factor correction is fundamental to reducing demand charges and improving efficiency. But in modern commercial and industrial environments, a hidden threat, harmonics, can undermine those benefits, causing increased losses and potential equipment failure. Harmonics are waveform distortions at multiples of the 50 Hz mains frequency, created by non-linear loads such as variable frequency drives and LED lighting.
Five ways harmonics sabotage your PFC system
- They create distortion power factor: harmonics inject distortion that lowers the overall power factor, combining the regular power factor with Total Harmonic Distortion (THD). More harmonics mean a lower power factor and higher bills.
- They cause overheating: excess current raises the operating temperature of transformers, motors and cables, accelerating wear and the risk of premature failure.
- They increase system losses: the extra current and resistance dissipate energy in the conductors, wasting power and negating the efficiency gains of PFC.
- They trigger resonance: the capacitors in standard PFC banks can resonate with harmonic frequencies, amplifying harmonic levels and causing severe voltage distortion.
- They reduce capacity: the distortion consumes system headroom, leaving less usable capacity on the infrastructure you already have.
Because standard PFC capacitors can make a harmonics problem worse, correction and harmonic mitigation belong together. A combined survey measures the distortion first, then designs correction that accounts for it, using passive or active harmonic filtering where needed.
Why harmonic mitigation is not optional
Left unmanaged, harmonics quietly erode the return on a PFC investment and shorten equipment life. Measuring power quality alongside power factor, and designing for both, is what turns correction into a durable, reliable saving rather than a short-lived one.
What are harmonics?
Voltage or current waveforms at frequencies that are integer multiples of the mains frequency (50 Hz in South Africa). They are created by non-linear loads such as variable frequency drives and LED lighting.
How do harmonics affect a PFC system?
They lower the overall power factor (through a distortion power factor), overheat transformers, motors and cables, increase system losses, can trigger resonance with PFC capacitors, and reduce usable system capacity.
What is distortion power factor?
A metric combining the system's regular power factor with the Total Harmonic Distortion (THD). More harmonics mean a lower distortion power factor and higher bills, even with capacitors installed.
Why is harmonic mitigation not optional?
Because harmonics can undermine the entire PFC investment. A holistic approach, combining correction with passive or active harmonic filtering, protects the equipment and the savings.