Taiyo Nippon Sanso (TNSC) has received an order for three 2-kW turbo refrigerators for a superconducting fault current limiter installation, according to The Gas Review.

The NeoKelvin®-Turbo 2kW refrigerators ordered from TNSC are the first product to be developed to cool a superconducting device anywhere in the world that uses neon as the refrigerant in turbo refrigerators. The NeoKelvin provides cooling capacity to 70K (-203oC), in the temperature range of liquid nitrogen (N2), but structurally does not require opening the low-temperature section for maintenance.

However, this is the first time that a turbo refrigerator has been used as a current limiter. Hirokazu Hirai, Project Manager of Cryogenic Development Project, Project Administration Sector at the Research and Development Division’s Project Promotion HQ, said, “Up to now, turbo refrigerators were not used in current limiters, but rather reciprocating Stirling or GM refrigerators were mainly used. This was because the cooling capacity required by the current limiter was at most 1 kW in the research stage. We were selected for the test facility because our product provides a suitable cooling capacity and a long maintenance period.”

The Moscow City Power was studying increasing their circuit breaking capacity to prevent fault currents due to increased power demand. However, extensive expense would have occurred to expand the capacity of their current equipment, so they were searching for a new method. A high temperature superconducting wire manufacturer in Russia, SuperOx, proposed a superconducting current limiter due to its superiority in terms of cost and behaviour capability, which led to the testing installation. TNSC received the refrigerator order at the request of the Japanese subsidiary of SuperOx, SuperOx Japan.

The refrigerators will be turned over at the end of June 2018, and then shipped to Moscow for onsite installation and trial operation. During testing, the refrigerators are scheduled to be used at one substation in Moscow, and then installed at all substations distributed widely throughout Moscow if indicated by the test results. The length of the testing period has not been specified.

TNSC has also installed five 2-kW refrigerators in Japan and one trial 10-kW refrigerator at the South Korean power corporation, Korea Electric Power. They have been testing refrigerators with superconducting cables since 2015 and, after a two-year test period, are continuing to work toward applications in commercial projects.