Harmonic Filter Chokes

Harmonic distortion in industrial power networks causes increased I²R losses, transformer overheating, and equipment malfunctions. Harmonic Filter Chokes are designed to block high-order harmonic currents, providing low-impedance paths for fundamental frequency while attenuating unwanted harmonics. Our chokes offer superior linear inductance profiles across wide frequency ranges, ensuring your harmonic mitigation system operates with stable impedance characteristics under non-linear loads. 

Rated System Voltage

400 V / 415 V / 480 V / 690 V AC

Tuning Frequency

189 Hz / 210 Hz / 134 Hz for 50 Hz systems

Inductance Tolerance

±5% (measured at rated current and fundamental frequency)

Core Material

CRGO silicon steel / Amorphous core (selected based on harmonic content and losses)

Insulation Class

Class H (180°C thermal endurance, tested as per IEC 60085)

Product Description

Non-linear loads distort current waveforms, resulting in poor power factor and higher demand charges. Our Harmonic Filter Chokes are optimized for detuned filter applications (typically 189 Hz/210 Hz/134 Hz), protecting capacitors from harmonic overload and allowing precise power factor correction without risk of resonance. This ensures long-term stability of capacitor banks and compliance with IEEE 519 and EN 61000-3-2 standards. 

Maximum Hot Spot Temperature

155°C continuous, 180°C for short duration under overload conditions

Rated Harmonic Current

Up to 150% of fundamental current

Total Inductor Losses

≤ 3 W per kVAR reactive power at specified harmonic spectrum

Dielectric Withstand Voltage

3.0 kV AC for 1 minute between windings and ground

Magnetic Flux Density (Bmax)

≤ 1.6 Tesla at maximum rated harmonic load

Short Circuit Thermal Withstand

1.8 × Irms for 1 second (verified per IEC 60076-6)

Detuning Reactance (Uk%)

Typically 6%, 7%, or 14% (based on capacitor voltage and tuning design)

Winding Configuration

Copper/Aluminum, multi-layer foil or round wire with thermal insulation barriers

Mounting Configuration

Rigid base-mounted with anti-vibration brackets and elongated mounting slots

Acoustic Noise Level

≤ 65 dB at 1 meter under full harmonic current load

Technical Advantages

Voltage amplification due to resonance between power factor capacitors and system inductance can damage insulation and degrade sensitive equipment. By introducing high-frequency impedance, our chokes dampen resonance peaks and provide dielectric relief to system components. Core saturation is minimized even during transient overloads due to high-quality, low-loss magnetic materials with tightly controlled flux density limits. 

Rapid load changes in variable frequency drives (VFDs), CNCs, and rectifier-based systems induce current surges and harmonic spikes. Harmonic Filter Chokes stabilize current flow through inductive smoothing and ensure system impedance remains within calculated thresholds. High thermal class windings and vacuum-impregnated coils ensure mechanical integrity under vibration and high-frequency thermal cycling. 

 

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Industry Applications

Variable Frequency Drive (VFD) Systems

Reduces harmonic current injection from VFDs, preventing distortion-related issues in motors, transformers, and upstream power systems. 

Power Factor Correction Panels

Protects capacitors from harmonic resonance and overload by shifting resonant frequency below dominant harmonic order. 

Renewable Energy Inverters

Attenuates switching harmonics from solar and wind inverters, ensuring grid compliance and minimizing electromagnetic interference. 

Uninterruptible Power Supply (UPS) Systems

Filters high-frequency noise and harmonics generated by inverter stages, improving system stability and output waveform quality. 

CNC and Servo Drive Systems

Stabilizes distorted current waveforms caused by fast switching operations, reducing stress on power distribution components. 

HVAC and Chiller Equipment

Minimizes current distortion from non-linear compressor loads, reducing nuisance tripping and improving overall system efficiency. 

Harmonic Filter Chokes

Eliminate Compliance Risks in Regulated Environments

Meeting harmonic limits under IEC, IEEE, and utility guidelines is essential in export-sensitive industries, renewable installations, and critical infrastructure. Our Harmonic Filter Chokes are precision-calibrated with tight inductance tolerance and low THDi contribution, enabling system designers to maintain grid code compliance with confidence. 

Whether you’re designing filters for 400V low-voltage panels or 11kV MV distribution, we supply chokes with current ratings up to 1000 A, inductance up to 50 mH, and insulation class up to H. Options include copper/aluminum windings, dry/encapsulated construction, and air or iron-core topologies based on required impedance and thermal profile. Finite Element Analysis (FEA) and thermal simulation validate each custom design for field reliability. 

Harmonic Filter Chokes

Having Doubts? Our FAQ

Check all our Frequently Asked Question

How does Frigate ensure inductance stability in Harmonic Filter Chokes under load variations?

Frigate designs chokes using low-loss magnetic cores with high linearity to maintain inductance across varying load currents. Finite Element Analysis (FEA) is used to simulate magnetic flux behavior under partial and full-load conditions. Core saturation is avoided by maintaining flux density below material thresholds. This ensures consistent harmonic filtering performance even under fluctuating non-linear loads. 

What measures does Frigate take to control thermal rise in high-current harmonic choke applications?

Frigate selects thermal Class H or F insulation systems based on current rating and duty cycle. Windings are dimensioned for low AC resistance and optimized surface area for heat dissipation. Vacuum impregnation enhances thermal conductivity and mechanical rigidity. Temperature rise is verified using simulation and test data as per IEC 60076-6. 

How does Frigate prevent mechanical vibration and acoustic noise in harmonic filter chokes for VFD systems?

Frigate uses interleaved lamination stacks and tight coil clamping to reduce magnetic flux-induced vibrations. Coils are resin-encapsulated or vacuum varnished to dampen acoustic noise during high-frequency operation. Core joints are precision-machined to minimize magnetostriction effects. These practices ensure low audible noise, especially critical in commercial and sensitive industrial environments. 

What testing standards does Frigate follow for harmonic filter choke qualification?

Frigate conducts routine and type tests in accordance with IEC 61558-2-20 and IEEE C57.110 standards. This includes inductance, impedance, high-voltage dielectric, temperature rise, and THDi attenuation tests. Harmonic filtering performance is verified using grid simulation setups. Each unit is also subjected to surge and insulation resistance testing before dispatch. 

Can Frigate design custom harmonic filter chokes for 690V or 11kV systems?

Yes, Frigate develops custom chokes for low-voltage and medium-voltage harmonic mitigation. High-voltage insulation systems and segmented winding designs are applied for dielectric strength and thermal management. Designs include air-gapped iron-core topologies for stable inductance under higher voltages. Each unit undergoes impulse and partial discharge testing as per voltage class. 

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LOCATIONS

Registered Office

10-A, First Floor, V.V Complex, Prakash Nagar, Thiruverumbur, Trichy-620013, Tamil Nadu, India.

Operations Office

9/1, Poonthottam Nagar, Ramanandha Nagar, Saravanampatti, Coimbatore-641035, Tamil Nadu, India. ㅤ

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Harmonic Filter Chokes

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Harmonic Filter Chokes

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