Medium Voltage Direct Current Disconnect Switches

Future U.S. Navy DC power distribution systems will require advanced switchgear technology to enable the reductions in volume, weight, cost, and maintenance possible with high-speed DC shipboard power distribution and protection systems. Disconnect switches are isolation devices which serve a critical role in the power system architecture, configuring buswork and associated equipment while safely isolating unpowered equipment. Under the SBIR Phase I effort, Diversified Technologies, Inc. (DTI) documented the Navy requirements, evaluated disconnect switch operational components in a trade study, and fabricated hardware. Based upon the trade study, a scalable, 100 – 4000 Ampere, two-pole, 12 kV disconnect switch design was selected and developed. A brassboard device was designed and built, demonstrating operation at 2000 A. The disconnect switch showed expected opening and closing performance. Voltage standoff was demonstrated at twice the rated voltage. The contact resistance was tested and measured, yielding an efficiency >99.99%. In addition, DTI developed conceptual models of modular switchgear cabinets capable of containing many internal disconnect switches for high power density configuration of multiple buses, power sources, and loads. MVDC disconnect switch feasibility and practicality were demonstrated by analysis, hardware fabrication, and testing in the Phase I Base effort. In the Phase II effort, DTI proposes to develop a family of air-cooled, high efficiency, high power density MVDC two-pole disconnect switches and accompanying cabinet enclosures for 12 kV MVDC distribution systems. These devices can be used in LVDC systems. DTI will complete the design for a family of full-featured high performance two-pole disconnect switches, and will build and test a 12 kV, 2 kA advanced Prototype with improved performance and network capabilities. In the Phase II Option 1 effort, DTI will continue testing the Prototype to include remote operation and finalize the design of the switchgear enclosure. In the Phase II Option 2 effort, DTI will build the switchgear enclosure, and deliver and install the switchgear enclosure with multiple Prototype disconnect switches in a Navy facility.