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Coaxial Insulated Bus Pipe for High Energy Application


TECHNOLOGY AREA(S): Electronics, 

OBJECTIVE: Develop a Medium Voltage Direct Current (MVDC) coaxial Insulated Bus Pipe (IBP) conductor and associated components for integration onto U.S. Navy ships. 

DESCRIPTION: A MVDC coaxial IBP conductor with the associated connectors, bulkhead penetrations, and shock excursion mounts for transmission of MVDC with voltages in the range of 6 kV to 12 kV and ampacity from 2000 to 4000 amperes is required to mitigate the challenges associated with cabling of available IBP technologies. Existing cables are limited in ampacity to approximately 400-700 amps per conductor, which requires multiple paralleled cables and terminations. Multiple paralleled copper cable conductors are difficult to install, heavy, and require more of the ship’s internal volume to meet the needs of future surface combatants. As such, higher conductor capacities are desired to support higher power distribution without the need to install and maintain multiple parallel cables and the associated terminations. The Navy, as well as shipyards, are seeking an innovative MVDC IBP conductor to improve power transmission and modular ship construction. Prior developments resulted in single phase IBP design appropriate only for Medium Voltage Alternating Current (MVAC) Navy distribution systems. Magnetic fields in MVDC IBP must be limited so as not to disrupt other systems nor increase the ship’s magnetic signature. To mitigate the magnetic fields of high power parallel MVDC conductors, a coaxial IBP configuration with the associated connectors, bulkhead penetrations, and shock excursion mounts are required. This effort will require finding innovative solutions to enable bus pipe technology to meet Naval traditional operating environment requirements These requirements are in accordance to the Navy’s MIL-STD-1399. The proposed design must be able to support a range of voltages from 6kVDC to 12kVDC and currents from 2000 to 4000Amperes. 3000Amperes at 12kVDC provides 36MW, which will allow a single coaxial MVDC IBP to support most loads. The design must also address shock excursions of bulkhead penetrations and mounts. Cost impacts will be evaluated for both the replacement of conventional cabling with IBP and tradecraft manpower reductions due to the configuration changes to preformed modular sections rather than pulling multiple long lengths of heavy cable throughout the ship during construction. In modular Navy ship construction, connection tubes and terminations must be maintenance free to reduce the risk of loose-connections and associated arc-faults. IBP must also meet US Naval application specification and standards to include Shock Tests (MIL-S-901); Cables, Electric, Low Smoke Halogen-Free (MIL-DTL-24643); Electromagnetic Interference Characteristics Requirements for Equipment (MIL-STD-461); Electromagnetic Environmental Effects Requirements (MIL-STD-464); 1399-MVDC interface specification; and IEEE 1580.1. A MVDC bus pipe specification does not currently exist; however, the MVDC IBP system is expected to comply with applicable Military standards and specifications, such as shock, fire and Electromagnetic Interference (EMI). Electric and magnetic fields must be managed and comply with Navy EMI requirements. 

PHASE I: Develop a concept for MVDC coaxial IBP conductor and associated connectors, bulkhead penetrations, and shock excursion mounts for transmission of 6 kVDC to 12 kVDC to support high power loads in Navy high power systems. Demonstrate the feasibility of a MVDC coaxial Insulated Bus Pipe design concept that meets the needs of the Navy as defined in the Description. Identify the technical feasibility of the proposed concept, and demonstrate the concept through modeling, analysis, and/or bench top experimentation where appropriate. Capture the technical feasibility and estimated production costs for the proposed concept in the Phase I Final Report. During a Phase I Option, if exercised, awardees will provide for initial design specifications and capabilities description to build a prototype solution in Phase II. 

PHASE II: Design and build prototype IBP sections in straight and complex configurations. Design and manufacture connectors necessary for testing. Provide viable design of bulkhead penetrations and mounts allowing for shock excursions. Develop a test plan to validate IBP to proposed Navy IBP standards. Test IBP prototypes to U.S. naval application specifications and standards to include: MIL-S-901, MIL-DTL-24643, MIL-STD-461, MIL-STD-464, 1399-MVDC interface specification, and IEEE 1580.1. 

PHASE III: Support the Navy in transitioning the technology for Navy use. The use of Insulated Bus Pipe in Navy construction will allow for modular installation and enable optimized workflow of high-power distribution systems installation in ship construction. Power distribution systems in all commercial Medium Voltage high current applications will benefit with reductions in size, weight and cost of cabling. Current commercial applications are in cruise ship design and urban underground power distribution in constrained environments. 


1. Artbauer J., Becker H., Butler J., Kuch H., Oeding D., Rumpf E., Steckel R.D. and Volcker O. “Power Systems Engineering Committee, Underground High-Power Transmission.” 7th IEEE/PES Transmission and Distribution Conference and Exposition, Atlanta, GA, 1979.

KEYWORDS: Insulated Bus Pipe; IBP; Solid Conductor; Coaxial DC Power; Modular Ship Construction; Bulkhead Penetration; MVDC Distribution; Medium Voltage Direct Current 

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