Balancing Reactor

Balancing reactors are critical passive components used in medium- and high-voltage systems where multiple capacitor banks operate in parallel. Differences in impedance, cable length, and internal tolerances among capacitors often result in unbalanced current distribution, leading to thermal stress, capacitor overloading, and eventual failure. These reactors introduce a controlled inductive impedance in series with each capacitor group, stabilizing current flow and ensuring uniform sharing of reactive power.  

Rated Voltage

Up to 33 kV (customizable as per system voltage level)

Frequency Range

50 Hz / 60 Hz ± 5%

Rated Current

Up to 2000 A (based on capacitor bank sizing and system configuration)

Inductance Value

0.1 mH to 10 mH (tuned as per system imbalance and harmonic profile)

Harmonic Attenuation

Effective mitigation of circulating currents at 5th, 7th, and higher harmonics

Product Description

Capacitor banks connected in parallel without proper impedance balancing are prone to internal circulating currents. These currents are not externally visible but contribute to accelerated insulation degradation, dielectric heating, and uneven aging. Balancing reactors are calculated to create an inductive voltage drop proportional to the flowing current, effectively damping inter-bank current oscillations. Reactance values are selected based on the rated current, frequency, and capacitor tolerance spread to ensure that the maximum current deviation remains within ±5% under all operating conditions. 

Insulation Class

Class F / Class H (selected based on thermal duty and ambient conditions)

Dielectric Strength

3.0 kV to 12.0 kV (depending on voltage class and insulation system)

Temperature Rise

≤ 80°C above ambient at rated current (hot-spot limit based on IEC 60076-6)

Core Material

Cold Rolled Grain Oriented (CRGO) steel / Amorphous core (application dependent)

Cooling Type

Natural air-cooled (AN) / Forced air-cooled (AF) based on thermal loading

Impedance Tolerance

±5% (precision tuning for current equalization across banks)

Mounting Type

Floor / Base mounted with vibration-damping supports

Ambient Temperature Range

-25°C to +50°C (de-rating required above 45°C)

Altitude Rating

Up to 1000 m without de-rating (higher altitudes on request)

Noise Level

< 60 dB at 1 meter (measured under rated load conditions)

Protection Degree

IP00 / IP20 / IP23 (depending on enclosure requirements and site conditions)

Standards Compliance

IEC 60076, IEC 60289, IEEE C57.16, IS 5553

Technical Advantages

High-order harmonics present in industrial environments can interact with capacitor banks to form resonant circuits, especially at the 5th, 7th, or 11th harmonic. The inclusion of a balancing reactor modifies the parallel resonance frequency of each bank and decouples them from each other, reducing the risk of harmonic amplification. This tuning ensures the system avoids harmonic resonance near known distortion frequencies and contributes to overall network impedance shaping.  

Capacitor overheating typically results from excessive RMS current, often originating from unequal reactive current sharing. Balancing reactors reduce RMS deviation by limiting high-frequency transient and steady-state inter-bank flows, which are otherwise unsupported by traditional protection systems. This inductive buffer minimizes the probability of dielectric breakdown and extends capacitor service life. Thermal design accounts for continuous operation at full load with hot-spot temperature calculations based on IEC 60076-6 standards.  

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Industry Applications

Parallel Capacitor Banks in Substations

Used to equalize current distribution across multiple capacitor groups, preventing circulating currents and ensuring uniform reactive power compensation. 

Power Factor Correction Panels in Industrial Plants

Stabilizes reactive current flow among capacitor stages, reducing unbalanced loading and extending capacitor lifespan in automated compensation systems. 

Static VAR Compensators (SVC)

Improves current symmetry between fixed and switched capacitor banks, avoiding dynamic current imbalances during fast reactive power transitions. 

High Voltage Harmonic Filter Banks

Decouples filter branches to prevent resonance interaction and ensures accurate tuning of each filter stage in harmonic-prone systems. 

Rolling Mills and Arc Furnace Installations

Dampens transient circulating currents between capacitor groups under rapid load variation, maintaining thermal limits and protecting dielectric insulation. 

Railway Traction Power Systems

Ensures balanced current sharing across trackside capacitors under varying inductive load conditions and prevents excessive capacitor stress. 

Design Parameters and Custom Engineering

Balancing reactors are typically specified with reactance values ranging between 0.5% to 5% of the capacitor bank impedance, with tolerances tight enough to ensure minimal power losses while achieving effective current balancing. Core material, flux density, air-gap profile, and thermal margins are engineered based on system operating voltage, frequency, and harmonic profile. High-voltage designs up to 33 kV are supported with dry-type or resin-cast construction, offering mechanical rigidity and high partial discharge immunity.  

Protection coordination becomes more predictable when current through each capacitor group is stabilized. Balancing reactors reduce nuisance tripping of overload and unbalance relays by eliminating peak deviations in capacitor current. Additionally, they prevent saturation of current transformers used in protection and monitoring circuits. Thermal sensors, embedded RTDs, or thermistors can be integrated into the reactor body for predictive maintenance and condition monitoring.  

Balancing Reactor

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Check all our Frequently Asked Question

How does Frigate customize balancing reactors for high-harmonic industrial environments?

Frigate evaluates the harmonic spectrum of the site, including THD levels and dominant harmonic orders, before designing the reactor. The reactor’s inductance is tuned to avoid resonant amplification with capacitor banks under distorted waveforms. Core materials are selected for low-loss performance under non-sinusoidal currents. This ensures thermal stability and resonance avoidance in harsh harmonic conditions. 

 

What makes Frigate balancing reactors suitable for high-voltage substation applications?

Frigate designs balancing reactors up to 33 kV with precise inductance control and partial discharge resistance. Each unit is built using high-grade insulation and vacuum pressure impregnation to handle environmental stress and electrical transients. Terminal spacing and creepage distances meet IEC and IEEE standards for high-voltage installations. The reactors integrate seamlessly into busbar and GIS systems without derating. 

How does Frigate address unbalanced loading in capacitor groups installed with unequal cable lengths?

Cable length variations lead to different impedance paths, creating current flow imbalances between capacitor banks. Frigate uses detailed impedance modeling of the installation to determine appropriate reactor values for each group. The balancing reactor introduces controlled reactance to normalize current distribution regardless of cable route. This approach ensures stable power factor correction and reduces capacitor overheating. 

Can Frigate’s balancing reactors be integrated into APFC panels with real-time switching?

Yes, Frigate designs balancing reactors to handle fast switching conditions common in APFC systems. Reactors are sized to limit transient inrush and manage harmonic stress during rapid step changes. Materials and core geometry are selected to avoid saturation during frequent capacitor bank operations. This enhances operational reliability and ensures compliance with reactive power demand.

How does Frigate ensure thermal performance under continuous and overload conditions?

Each reactor is thermally rated using IEC 60076-6 guidelines with a focus on hotspot temperature limits and continuous load endurance. Frigate simulates overload behavior under 110–120% rated current for thermal margin verification. Coil windings are designed with optimal airflow and insulation class F or H, depending on duty cycle. Sensors can be embedded for condition monitoring and predictive maintenance planning. 

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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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Balancing Reactor

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