A Passive Harmonic Filter is an L-C (inductor-capacitor) network designed to reduce specific harmonic currents in an electrical system by providing a low-impedance path for those harmonics.
Passive Harmonics Filters
Passive Harmonic Filters – Power Quality You Can Trust
At PurityElec, we design Passive Harmonic Filters that improve power quality by reducing harmonic distortion, increasing energy efficiency, and protecting your electrical network. Engineered for reliability and compliance with global standards, our filters are the perfect choice for industrial, commercial, and renewable energy applications where stable, distortion-free power is essential.
Key Features
• Effective Harmonic Mitigation – Reduces Total Harmonic Distortion (THD) to meet IEEE 519 and IEC standards.
• Improved Power Factor – Enhances system efficiency and reduces reactive power charges.
• Rugged Design – Built to withstand harsh environments and continuous operation.
• Energy Saving – Minimizes overheating and losses in cables, transformers, and motors.
• Customizable – Available in multiple ratings and configurations to suit your load profile.
Applications
• Industrial plants with VFDs, rectifiers, or large nonlinear loads
• Commercial buildings with high lighting and IT equipment loads
• Renewable energy systems with inverters and converters
• Data centers, hospitals, and critical infrastructure
• HVAC and large motor-driven systems
| Technical Specifications | |
|---|---|
| Voltage Range | 380V – 690V AC |
| Current Ratings | 10A – 2000A |
| Frequency | 50Hz / 60Hz |
| THD Reduction | Up to 90% (depending on load) |
| Power Factor Improvement | Up to 0.98 lag |
| Standards Compliance | IEEE 519, IEC 61000-3-4 |
| Enclosure | IP20 / IP23 / IP54 options available |
| Cooling | Natural or forced air cooling |
Why Choose PurityElec Passive Harmonic Filters?
With advanced engineering and a focus on performance, PurityElec filters deliver:
✔ Reduced downtime and equipment wear
✔ Lower maintenance and operational costs
✔ Compliance with stringent harmonic distortion regulations
✔ Longer lifespan for sensitive electrical equipment
Frequently Asked Questions
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Q1. What is a Passive Harmonic Filter?
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Q2. Why are Passive Harmonic Filters important?They help:
- • Reduce equipment overheating
- • Prevent nuisance tripping of breakers
- • Improve power factor
- • Reduce losses in transformers, motors, and cables
- • Ensure compliance with utility and international power quality standards
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Q3. Who needs Passive Harmonic Filters?
- • Industries with non-linear loads (VFDs, UPS, rectifiers, arc furnaces)
- • Commercial complexes, data centers, and hospitals
- • Renewable energy plants with inverters
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Q4. How does a Passive Harmonic Filter work?A PHF consists of tuned LC circuits that resonate at a specific harmonic frequency, diverting harmonic currents away from the main system and reducing their impact.
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Q5. Can PHFs filter all harmonics at once?No. PHFs are usually tuned for specific harmonic orders (e.g., 5th, 7th, 11th). Multi-tuned or hybrid configurations can target multiple harmonic orders.
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Q6. What is the difference between tuned and detuned passive filters?
- • Tuned Filters: Precisely tuned to a specific harmonic, but may risk resonance with system impedance.
- • Detuned Filters: Slightly off-tuned to prevent resonance, commonly used with capacitor banks for PF correction.
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Q7. Where are Passive Harmonic Filters installed?
- • At the output of VFDs, UPS systems, or rectifiers
- • Alongside capacitor banks in industries
- • In power distribution networks where harmonics exceed standards
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Q8. Do Passive Harmonic Filters improve power factor?Yes, they often include capacitors, providing reactive power support while filtering harmonics.
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Q9. Are PHFs suitable for variable loads?PHFs work best for steady or predictable harmonic sources. For highly variable or multiple harmonic orders, Active Harmonic Filters (AHF) may be more effective.
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Q10. Which standards are followed for PHF design?
- • IEEE 519 (Recommended limits for harmonics)
- • IEC 61000 series (Electromagnetic Compatibility & Power Quality)
- • Local utility regulations on harmonic levels
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Q11. How do we know if a PHF is needed?
- • Harmonics above permissible levels (THD > 5% for current)
- • Frequent equipment overheating
- • Nuisance tripping of breakers or relay operations
- • Distorted voltage/current waveforms measured during a harmonics audit
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Q12. What are the key benefits of Passive Harmonic Filters?
- • Simple, robust, and low-maintenance
- • Reduces THD in current and voltage
- • Improves equipment lifespan and reliability
- • Cost-effective for targeted harmonic orders
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Q13. What are the limitations of Passive Harmonic Filters?
- • Tuned for specific harmonics only
- • Can cause resonance if not designed properly
- • Not ideal for highly fluctuating loads or multiple harmonic orders
- • Fixed compensation; no dynamic adjustment