DC Reactor

DC reactors are essential for managing ripple currents generated by rectified AC inputs or high-frequency switching from converters. Inadequate attenuation of these ripple components can result in elevated RMS current stresses on filter capacitors, leading to premature dielectric failure and thermal runaway. Properly sized inductors in the DC link suppress ripple content, maintain a stable DC voltage profile, and enable optimal energy transfer between rectifier and inverter stages.  

Rated Voltage

Up to 1500 VDC

Frequency Range

DC to 3 kHz (for ripple and transient attenuation)

Rated Current

Up to 3000 A continuous

Inductance Value

0.1 mH to 50 mH (customizable based on application)

Harmonic Attenuation

Up to -40 dB at dominant ripple frequencies

Product Description

Rapid changes in current (high di/dt) across switching devices can cause overshoots, electromagnetic stress, and thermal cycling in power semiconductors such as IGBTs, MOSFETs, and diode bridges. DC reactors act as current-limiting impedance to moderate the rate of current rise during fault or load transition events. This controlled response reduces peak junction temperatures, minimizes stray inductance-induced voltage spikes, and enhances the overall reliability of the power conversion system.  

Insulation Class

Class F / Class H

Dielectric Strength

3.0 kV for 1 minute (line-to-ground)

Temperature Rise

≤ 85°C at full load (ambient 40°C)

Core Material

Cold-rolled grain-oriented silicon steel / Amorphous alloy

Cooling Type

Natural air / Forced air / Liquid cooled

Impedance Tolerance

±10% standard (tighter tolerance on request)

Mounting Type

Floor-mounted / Panel-mounted / Frame-integrated

Ambient Temperature Range

-25°C to +55°C

Altitude Rating

Up to 2000 meters without derating

Noise Level

< 65 dB at 1 meter distance

Protection Degree

IP00 / IP20 / IP54 (based on enclosure design)

Standards Compliance

IEC 60076-6, IEC 61558, UL 508, RoHS compliant

Technical Advantages

Systems with multiple converters connected to a common DC bus often exhibit resonance phenomena due to interaction between line inductance and distributed capacitance. These resonant conditions amplify low-order and high-frequency harmonics, destabilizing voltage regulation and causing circulating currents. Appropriately tuned DC reactors introduce impedance at problematic frequencies, dampen oscillatory modes, and improve harmonic impedance profiles. This contributes to compliance with IEEE 519 or IEC 61000-3-6 harmonic limits and ensures safe operation of interconnected converters. 

Large DC capacitor banks experience high inrush currents during initial energization, often exceeding nominal ratings of upstream switching devices. DC reactors mitigate this by providing a series impedance that limits charging current during power-up or capacitor switching events. This controlled ramp reduces stress on circuit breakers, contactors, and busbars, preventing nuisance tripping and mechanical wear. Reactors also prevent DC link overvoltage conditions during regenerative operations in motor drives by absorbing back-fed energy in the magnetic core. 

 

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Industry Applications

UPS Systems (Uninterruptible Power Supply)

Stabilizes DC link voltage, filters high-frequency transients, and reduces capacitor inrush during charging and load step transitions. 

Battery Energy Storage Systems (BESS)

Manages bidirectional current flow, suppresses ripple, and protects converters from fault currents during fast charge/discharge operations. 

HVDC Transmission Systems

Damps harmonic oscillations, limits current surges, and filters low-frequency distortion in long-distance high-voltage direct current networks. 

Solar PV Inverters

Filters ripple between MPPT stage and inverter bridge, reducing electromagnetic noise and stabilizing energy transfer under varying irradiance. 

Electric Traction Systems

Controls dynamic load transitions, protects rectifier/inverter bridges, and reduces stress on DC bus components during regenerative braking. 

Crane and Lift Systems

Attenuates large ripple and harmonic currents generated during arc formation, protecting power converters and improving voltage regulation. 

 

Customization Based on Application Topology

Each power conversion topology—whether in VFDs, UPS systems, energy storage converters, or HVDC transmission—demands specific inductance, thermal, and frequency response characteristics. DC reactors are tailored for inductance values that consider capacitor ESR, switching frequency, and permissible voltage ripple. Design parameters such as leakage inductance, insulation class, and mounting footprint are selected based on application constraints and environmental stress profiles. Reactors can also be co-designed with filter banks or crowbar circuits for coordinated protection schemes. 

Large reactors are subjected to vibration, mechanical shock, and thermal expansion cycles during operation, particularly in mobile or high-power applications. Mechanical design of DC reactors incorporates structural reinforcement, resin encapsulation, and anti-vibration mountings to prevent core delamination and winding movement. Terminations are engineered for high-current, low-resistance connections with busbar or cable entry options. Space constraints are addressed through compact core geometries and modular stacking configurations for panel-mounted or floor-mounted integration. 

DC Reactor

Having Doubts? Our FAQ

Check all our Frequently Asked Question

How does Frigate ensure DC reactors maintain stable inductance under varying thermal and electrical loads?

Frigate uses precision-wound copper coils and selects core materials with minimal thermal drift in permeability. Finite Element Analysis (FEA) simulations validate thermal hotspots and flux uniformity. This ensures inductance remains stable even under prolonged overload conditions. Reactors are tested across full thermal cycles to guarantee long-term performance. 

What design considerations does Frigate use to minimize core saturation during regenerative braking events?

Frigate incorporates calculated air gaps and selects high-saturation flux density cores like M4-grade silicon steel or amorphous alloys. Saturation limits are modeled based on worst-case regenerative fault currents. This prevents inductance collapse during reverse energy flow. Reactors maintain linear response to protect power semiconductors and capacitors. 

How does Frigate size DC reactors for applications with multiple parallel converters on a shared DC link?

Frigate analyzes the impedance profile of the DC bus and models inter-converter harmonic interaction. Custom inductance values are selected to damp resonance without affecting converter control dynamics. Each reactor is tuned based on the equivalent capacitance, switching frequency, and load synchronization. This improves system stability and prevents circulating currents. 

How does Frigate design DC reactors to handle high di/dt fault conditions in energy storage systems?

Frigate calculates di/dt limits based on IGBT or MOSFET safe operating areas and energy storage system short-circuit levels. Reactors are designed with high mechanical rigidity and low leakage inductance to contain fault energy. Air gaps are optimized to avoid magnetic shock saturation. This protects both upstream and downstream components. 

What construction options does Frigate offer to meet diverse mechanical and environmental constraints in DC reactor installations?

Frigate provides open-frame, resin-encapsulated, and enclosed DC reactors based on the installation environment. Mechanical design is tailored for vibration-prone or high-humidity locations using anti-corrosive coatings and epoxy systems. Forced-air or liquid-cooled variants are available for high ambient temperature zones. All constructions comply with IEC and UL insulation class requirements. 

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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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DC Reactor

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