Superior Fault Current Limiter

Low-cost, high-efficiency superconductors and the scalable methods for their production

The Need

Fault current limiters (FCLs) are relatively new devices that are designed for limiting excessive electrical current to an electrical grid or system in the event of an electrical fault. Current FCL designs use cryogenic liquid to maintain superconductor cables at 80 K, this process is costly and energy intensive leading to a low efficiency. Thus, there is a need for technologies able to reduce FCL energy loss and maintain state-of-the-art fault protection simultaneously.

The Technology

Researchers at The Ohio State University, led by Dr. Michael Sumption, have developed a magnesium diboride (MgB2) based FCL that reduces operational costs while maintaining the highest safety standards. Using MgB2 superconductive cables, instead of the standard YBCO, leads to a huge reduction in the manufacturing cost. The drawback to this is MgB2 needs to operate at a lower temperature 20-30 K, this is achieved by a cryocooler and novel circuity. The novel FCL circuitry minimizes total heat in the cryogenic portions of the current leads, the device responsible for transporting current to cryogenic temperatures and back, and mitigates both energy loss and damage to upstream devices stemming from an electrical surge. By reducing both the cost of the superconductor, removing the need for expensive cryogenic liquid and cryogenic storages containers a huge operational manufacturing cost savings is realized, leading to greater efficiency.

Commercial Applications

  • Electrical transmission and distribution networks
  • Superconductivity technologies


  • Uses feed through a section of copper rods
  • Minimizes total heat leak from FCL systems
  • More energy efficient
  • Scalable design principles

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