Superconductive cables are the eco-friendly, next-generation transmission system that enables large storage of electricity to be transmitted with high efficiency using lower voltages compared to high-voltage underground cables. They have high market potential and knock-on effects that could present a new paradigm for present-day electrical systems. Furthermore, when the joist technology for superconductive cables is fully developed, current substations can be converted to small-size switching stations and fewer new substations will need to be built. And in the future, superconductive cables may replace extra-high voltage large storage overhead conductors as well. Such benefits will contribute to greater social acceptance and enhanced convenience to citizens by helping resolve the NIMBY attitude toward unpleasant facilities. Furthermore, it will contribute significantly to the power grid business, which will be one of the core competitive technologies among nations in the future. Products in the superconductive cable system include superconductive cables, middle and terminal connection boxes, cooling systems to keep the superconductive cables at an extra-low temperature of -200 degrees, and control systems. Liquid nitrogen is used as the refrigerant.

Types and purposes

The superconductive cable system is classified into distribution and transmission cables.Transmission cables can be classified into AC or DC systems.

• Superconductive distribution cable systems: AC22.9kV 50MVA and AC22.9kV 120MVA
  - Replaced multiple-line underground distribution cables with single-line superconductive cables
  - Replaced transmission cables between substations with superconductive distribution cables
 
• Transmission AC system: AC154kV 600MVA and 1GVATr
  - Replaced multiple-line underground distribution cables with single-line superconductive cables (Replaced and newly built saturated and worn-out lines)
  - Reduced lines between substations for simplicity
 
• Transmission DC system: DC80kV 500MW
  - Large storage, long distance transmission