Multi-bath apparatus and method for cooling superconductors

A method for cooling a superconducting device, the method comprising:

• A. Surrounding the superconducting device with a first cryogen from a cooling bath maintained at a first pressure;
• and
• B. Surrounding the cooling bath with a second cryogen from a shield bath maintained at a second pressure;
• in which the cooling bath and the shield bath are in a thermal relationship with one another and the shield bath provides cooling to the cooling bath and the first pressure exceeds the second pressure.

A method of protecting an electrical system from a fault current event, the method comprising the steps of:

• A. Providing the electrical system with a fault current limiter;
• B. At least partially submerging the fault current limiter in a cooling bath comprising a first cryogen having a first pressure;
• C. At least partially submerging the cooling bath in a shield bath comprising a second cryogen having a second pressure, the cooling and shield baths in a thermal relationship with one another and the shield bath provides cooling to the cooling bath;
• and
• D. Maintaining the cooling and shield baths such that the first pressure is greater than the second pressure.