HV Air-Core Current-Limiting Reactor: Applications and Technical Advantages

1. Product Overview

The high-voltage air-core current-limiting reactor is an essential short-circuit current limiting device in power systems. Utilizing an air-core winding structure without iron core, it automatically generates high impedance through its inductance characteristics when a short-circuit fault occurs, effectively limiting the magnitude and rise rate of fault current to protect transmission and distribution equipment. RECON Power Technology specializes in the R&D and manufacturing of dry-type air-core reactors, serving power generation, transmission, and distribution sectors with products known for excellent linearity, low losses, and high reliability.

2. Application Scenarios

2.1 Power Plant Outlet Current Limiting

Installing a current-limiting reactor at the generator outlet effectively limits the short-circuit current during generator terminal faults, ensuring circuit breakers can operate reliably within their rated interrupting capacity. This prevents catastrophic failures such as breaker explosion or contact welding caused by excessive fault current. The solution is particularly valuable for small-capacity generator grid integration, reducing the interrupting capacity requirements for switchgear and saving electrical equipment investment.

2.2 Substation Bus-Tie Current Limiting

When two or more transformers operate in parallel or substations are interconnected via bus-tie circuits, the system short-circuit capacity increases significantly. Connecting a high-voltage air-core current-limiting reactor in the bus-tie circuit limits the fault current to levels within equipment withstand capability while maintaining a reasonable voltage drop during normal operation without compromising power quality.

2.3 Urban Distribution Network Expansion

As urban distribution networks require capacity expansion to meet growing loads, existing switchgear interrupting capacity often cannot handle the increased short-circuit levels. Installing current-limiting reactors at feeder outlets enables distribution network expansion without replacing existing switchgear, substantially reducing retrofit costs and outage time.

2.4 Large Motor Starting Current Limiting

Large high-voltage motors driving fans, pumps, and compressors generate starting currents of 5 to 7 times rated current, causing significant stress to the power grid and transformers. Connecting a current-limiting reactor in the motor circuit limits starting current to 2 to 3 times rated current, ensuring smooth motor starting while minimizing grid disturbance.

2.5 Industrial Plant Distribution Protection

Industrial facilities in steel, chemical, and mining sectors have complex internal distribution networks with high short-circuit capacity and multiple distribution levels. Installing high-voltage air-core current-limiting reactors at key distribution nodes enables selective fault protection, preventing local faults from escalating into plant-wide blackouts.

3. Technical Advantages

3.1 Dry-Type Air-Core Design

RECON's high-voltage current-limiting reactors adopt a dry-type air-core design. The coreless structure eliminates saturation issues, maintaining constant inductance from rated current through fault current levels with excellent linearity. Compared to oil-immersed reactors, the dry-type design eliminates oil leakage risks, requires no periodic maintenance, and offers significantly lower operating costs.

3.2 High-Quality Insulation System

The products utilize Class F or Class H epoxy resin impregnated fiberglass wound insulation systems with superior insulation performance. Partial discharge levels are controlled below 10 pC. Vacuum pressure impregnation ensures complete filling of winding gaps without voids, providing a thermal aging life exceeding 30 years.

3.3 Multi-Layer Parallel Winding Technology

The multi-layer parallel winding structure uses multiple parallel conductors per layer for uniform current distribution. Eddy current and stray losses are substantially reduced. Precise calculation of turns and conductor cross-section for each layer ensures balanced current distribution and eliminates local hot spots.

3.4 Low Loss Design

Through optimized conductor cross-section, improved transposition techniques, and eddy current control, product losses are maintained at 80% to 90% below national standard specified values. For a typical 1000A rated product, per-phase losses are approximately 3 to 5 kW, delivering significant energy savings over long-term operation.

3.5 Low Noise Operation

Optimized magnetic path design and winding fixation structure, combined with appropriate vibration damping, keeps operating noise levels below 55 dB(A), meeting environmental requirements for urban substations and indoor installations.

3.6 Custom Design Capability

RECON offers customized design based on specific customer requirements including rated inductance, rated current, rated voltage, mounting orientation, and connection configuration. All products are type-tested by nationally accredited testing authorities.

4. Technical Specifications

XKGKL series dry-type air-core current-limiting reactor typical parameters: rated voltage 6 kV to 35 kV, rated current 200 A to 5000 A, rated inductance 0.1 mH to 100 mH, reactance ratio 3% to 12%, thermal class F or H, noise level ≤55 dB(A), partial discharge ≤10 pC, ambient temperature -40°C to +55°C, mounting vertical or horizontal.

5. Conclusion

High-voltage air-core current-limiting reactors play an indispensable role in modern power systems. From power plants to end users, from urban distribution networks to industrial facilities, their applications continue to expand. RECON Power Technology, with deep electromagnetic design expertise and rigorous quality control, delivers high-performance and high-reliability current-limiting reactor products to support safe and reliable power system operation.