RL Load Reactor

Rapid changes in output current from drives induce significant di/dt stress on motor insulation systems, especially over long cable lengths. RL Load Reactors introduce inductive impedance that slows down the rate of current rise, effectively damping high-frequency components responsible for premature winding failure. This helps maintain the dielectric integrity of motor insulation, particularly in applications with frequent starts, regenerative braking, or varying torque loads. 

Rated Voltage

380 V / 415 V / 480 V / 690 V AC (Line-to-Line)

Frequency Range

50 Hz / 60 Hz ±5%

Rated Current

Up to 1000 A (customizable as per application)

Inductance Value

1% to 5% of system impedance (Z)

Harmonic Attenuation

Up to 35% THD reduction (5th, 7th, 11th harmonics)

Product Description

Cable lengths exceeding 15 meters between VFD and motor introduce impedance mismatch, resulting in voltage reflections that can exceed twice the DC bus voltage. These overvoltages lead to insulation breakdown in motor windings and induce partial discharge phenomena. RL Load Reactors reduce the peak voltage by moderating the voltage rise time, attenuating reflected wave magnitude, and minimizing dielectric stress on terminal insulation. 

Insulation Class

Class F (155°C) or Class H (180°C)

Dielectric Strength

≥ 2500 V AC for 60 seconds

Temperature Rise

≤ 80°C above ambient at rated load

Core Material

Low-loss, cold-rolled silicon steel or CRGO

Cooling Type

Natural Air Cooled (AN) / Forced Air on request

Impedance Tolerance

±10%

Mounting Type

Base / Wall Mount (customizable mechanical footprint)

Ambient Temperature Range

–25°C to +50°C (derating required above 40°C)

Altitude Rating

Up to 1000 meters without derating (derating required above)

Noise Level

< 65 dB at 1 meter

Protection Degree

IP00 / IP20 / IP23 (on request)

Standards Compliance

IEC 60076, IEC 60289, IEEE 519, UL Recognized (optional)

Technical Advantages

Low-order harmonics generated by VFDs contribute to non-linear load behavior, which impacts transformer loading, leads to overheating of conductors, and increases neutral current. RL Load Reactors act as a passive filter by providing impedance to 5th, 7th, and 11th harmonic currents, thereby reducing total harmonic distortion (THD) on the load side. Their implementation supports IEEE 519 compliance and protects upstream distribution assets from thermal degradation and resonance effects. 

Switching operations, utility events, or internal drive functions can produce sharp voltage spikes, which affect both motor life and drive stability. RL Load Reactors suppress these voltage transients by limiting instantaneous current flow, effectively acting as a first-order RL low-pass filter. This helps reduce voltage notching and stabilizes the voltage profile seen by both motor and inverter during dynamic load transitions. 

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Industry Applications

Pumps and Compressors

Dampens current surges during torque transients, preventing overcurrent trips and minimizing mechanical stress on driven equipment. 

Elevator and Hoist Control Systems

Provides impedance for dynamic braking and load regeneration, reducing harmonic reflection and stabilizing motor voltage under varying loads. 

Conveyor Automation Systems

Minimizes reflected wave effects in long motor cables, ensuring waveform integrity and reducing EMI across drive-controlled conveyors. 

HVAC Motor Drives

Filters low-order harmonics and limits inrush current in air handling units, improving motor performance and system reliability. 

Centrifugal and Axial Fans

Controls rapid current fluctuations during start-stop cycles, reducing motor heating and preventing nuisance tripping in fan control systems. 

Crane and Lift Systems

Buffers mechanical shock during abrupt load shifts, enhancing torque regulation and reducing current distortion in drive outputs. 

 

Minimization of Electromagnetic Interference Propagation

High-frequency switching by IGBT-based drives generates conducted and radiated EMI, which propagates through motor leads and can interfere with adjacent control wiring. RL Load Reactors suppress high-frequency content on the load side by smoothing out the pulse width modulated (PWM) waveforms. This reduces the amplitude of differential-mode noise and supports electromagnetic compatibility (EMC) requirements in noise-sensitive installations. 

Drives frequently encounter overvoltage or overcurrent trips due to line disturbances, regenerative loads, or cable reflections. RL Load Reactors stabilize current profiles and help maintain drive operation within manufacturer-specified trip thresholds. Their impedance dampens overvoltages resulting from fast switching or load changes, supporting uninterrupted drive function in variable load environments. 

RL Load Reactor

Having Doubts? Our FAQ

Check all our Frequently Asked Question

How does Frigate ensure RL Load Reactors maintain thermal stability under continuous full-load operation?

Frigate uses Class F or H insulation systems rated for high-temperature endurance during prolonged load cycles. Each unit is thermally tested to verify hotspot stability under maximum rated current and ambient conditions. Core materials are selected for low iron loss at industrial frequencies. This design prevents saturation and overheating during harmonic-rich or continuous-duty environments. 

What customization options does Frigate offer for RL Load Reactors used in regenerative drive applications?

Frigate designs reactors with optimized core gaps and specific inductance values for systems where bi-directional current flow occurs. Regenerative drives demand precise impedance to manage back-fed energy without destabilizing the DC bus. Frigate engineers adjust conductor size, core material, and thermal margins accordingly. Each reactor can be tailored to application-specific braking profiles and load inertia. 

 

How does Frigate design RL Load Reactors to control harmonic resonance in multi-drive systems?

When multiple drives operate on a common bus, harmonic resonance can amplify certain frequencies. Frigate’s reactors are designed with calculated impedance to shift resonance points away from dominant harmonic orders. Finite Element Analysis (FEA) is used to validate magnetic flux distribution under harmonic-rich conditions. The result is improved damping across the harmonic spectrum, reducing system-wide distortion. 

How do Frigate’s RL Load Reactors handle voltage notching in weak grid installations?

Weak grids suffer from low short-circuit capacity, making them prone to deep voltage notches during switching. Frigate’s RL Load Reactors limit the rate of current rise, preventing aggressive current draw from the supply. The added impedance reduces voltage collapse during thyristor or soft-starter operation. This ensures better voltage profile and improved power quality under constrained grid conditions. 

What design considerations does Frigate apply for RL Load Reactors used in high-altitude environments?

Air density decreases with altitude, affecting the cooling efficiency of magnetic components. Frigate derates reactor capacity or increases surface area and airflow paths for high-altitude deployment. Core and winding designs are modified to maintain thermal performance under reduced convection. Altitude-specific performance is validated using thermal modeling and accelerated life-cycle simulations. 

 

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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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RL Load Reactor

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