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Air Core Reactor

Product Overview & Application


Air-Core reactors provide a linear impedance with respect to current which is crucial in many applications where an iron core reactor would otherwise saturate.

Some typical applications include:

  • Shunt Reactors - Compensate for the capacitive currents of long transmission lines or cables, allowing more active energy to pass through the system.
  • Current Limiting Reactors - Limit the fault currents to levels compatible with existing protection/control equipment and as a result provide for a very cost-effective solution.
  • Filtering Reactors - Usually connected with capacitors and resistors in filter circuits to reduce harmonic content in the network which cause higher losses, high neutral currents and interference with computer and telecommunications equipment and which are responsible for high harmonic distortion levels.
  • Neutral Grounding Reactors - Connected between the neutral of a power system and ground to limit the line-to-ground current to a desired value under system ground fault conditions.



Coils are wound with aluminum (Al) or copper (Cu) conductors arranged in layers or discs with special consideration given to minimizing eddy losses. UL listed insulation system is used throughout the winding and coils are vaccum pressure impregnated with Epoxy to provide a high degree of protection from humidy and other environmental contaminants. Alternately, for particularly harsh conditions Rex offers ACR's with solidly cast epoxy coils.

For Outdoor applications, special UV coatings are utilized to protect the insulation from the sub. Reactors can be supplied either as single-phase coils individually supported on insulators or alternatively as three phase coils stacked vertically.

Product Specification

Capacity  up to 10,000kVAR
Voltage Class  up to 25kV
Cooling  Self Cooled (ANN / AN)
Frequency  60Hz (50/60Hz Optional)
Conductors  Copper (Cu) or Aluminum (Al) Windings
Insulation System  220°C Insulation System (150 °C Temp Rise Max)
Sound Level  Below 40dBA
Enclosure Type  Open Construction (Enclosure options available)
Enclosure Finish  ANSI 61 Grey Powder Coat

 Std Production Tests per IEEE C57.16 & IEEE C57.32

  • Winding Resistance
  • Impedance Measurement
  • Loss Measurement
  • Turn to Turn Test

 Optional Type Tests

  • Lightning Impulse Test (BIL)
  • Chopped-wave Impulse Test (For Series Reactors)
  • Power Frequency withstand Voltage Test
  • Temperature Rise Test
  • Sound Level Test
Warranty  12 Months (See Warranty and Limitations)
Quality System  ISO 9001:2015 Quality Management System
  • CSA Certified
  • UL Listed
Reference Standards
  • IEEE/ANSI C57.16
  • IEEE/ANSI C57.32