Sastry Pamidi

Power cables have terminations on each end to maintain dielectric integrity. Terminations interconnect the power cable with its high electric field to air-insulated components with lower electric fields and changing ambient conditions. In the case of a superconducting power cable, the terminations act as an interface between the cable and the grid.  In addition, these terminations manage the thermal gradient from the cryogenic temperature components to the ambient temperature components. The terminations additionally need to link the cryogenic environment in the cable with the ambient temperature environment of the non-superconducting elements of the power system, such as copper cables, power transformers, circuit breakers, instrumentation transformers, and disconnect switches.

Superconducting power devices, such as cables, fault current limiters, or transfers, need feedthroughs that connect them with other elements of the power system that stay at ambient temperature. The higher temperatures of these components cause substantial heat influx into the terminations and consequently into the superconducting cable if no countermeasure is installed.

The new technology developed, which solves these issues, comprises a method of maintaining an operating cryogenic temperature range of a low temperature system (e.g., including a superconductor). A heat intercept is attached to the lower temperature system that is temperature critical. This part may be, for example, the termination or intersection point between a copper conductor and high temperature superconducting cable. The heat intercept is pre-shaped to conform to the shape of the temperature-critical part. The heat sink, or at least the portion attached to the low temperature system, is formed of a heat conductive material. The heat intercept includes a heat sink, an inlet channel, and an outlet channel. The inlet and outlet channels extend from the heat sink, as the heat sink abuts the temperature-critical part of the system. The heat sink, inlet channel, and outlet channel are configured such that the inlet channel is in open communication with the interior of the heat sink and the outlet channel also is in open communication with the interior of the heat sink.  A cryogenic gaseous medium is injected into the inlet channel, such that the gaseous medium enters the heat sink through the inlet channel and exits the heat sink through the outlet channel. Thus, since heat is transferred to and absorbed by the gaseous medium within the heat sink, the gaseous medium has a higher temperature when exiting the heat sink than when entering the heat sink.

Advantages

• Compact design
• Vacuum tight
• Low pressure drop
• Highly efficient due to maximum heat transfer
• Simple design and manufacturing
• Optimal for a gas having low viscosity