N211-038 TITLE: Next Generation Laminated Bus Bar Technologies
RT&L FOCUS AREA(S): Directed energy
TECHNOLOGY AREA(S): Materials / Processes
OBJECTIVE: Increase the reliability and confidence of laminated bus bars through the development of new insulation materials and Non-Destructive Testing (NDT) methods.
DESCRIPTION: DDG 1000 Class utilizes an Integrated Power System (IPS) to generate and distribute power to the propulsion system, ship service distribution system, and combat systems. Multi-layer, multi-conductor, laminated bus bars are used within the IPS system to distribute local high voltage (4160 VAC RMS) power distribution within switchboards, propulsion motors/drives, and other high voltage equipment. We currently use multi-layer, multi-conductor, laminated bus bars in the system.
While laminated bus bars are used throughout the power industry, recent bus bar failures have highlighted the need for new technologies that will increase the reliability of bus bars in a non-sterile, shipboard environment. ASTM B187 provides guidance for copper commercial bus bars. Development areas of interest are insulation materials, conductor-connection interfaces, and associated NDT procedures.
Bus bars must be capable of handling various voltages, frequencies and currents dependent upon their application including maximum layer-to-layer potentials of 10.5 kV peak to ground, +/- 6500 VDC, 60A and pulse width modulation (PWM)-switched output waveforms of 3300 VAC 0-18Hz 450A. Nominal PWM switching frequency between the range of 1kHz and 20kHz.
Installed bus bars must be capable of passing qualification testing for a shipboard environment including to MIL-S-901 Grade A, Type A, Class 1 Shock, MIL-STD-167-1 Vibration, and MIL-STD-810 for Temperature and Humidity. Bus bars shall be mechanically compliant / flexible to provide excellent resistance to stresses from the above shock and vibration standards as well as installation handling. Bus bars shall meet the requirements of MIL-DTL-23928.
Quality & Assurance (Q&A) processes and NDT technologies should be developed. This path will allow for the identification of insulation flaws prior to installation and the ability to verify bus bar condition through service life of current bus bars. High fidelity Q&A processes reducing the number of defective units being delivered to the fleet would increase confidence of delivered bus bars. Currently, partial discharge testing based on IEC 60270 is used to determine insulation material condition. New scanning technologies or test methods are needed to verify insulation condition which would increase confidence in in-service and spare bus bars.
PHASE I: Develop a concept for alternative insulation materials, connector interfaces, and NDT method in accordance with specifications and requirements outlined in the topic description section. Demonstrate the feasibility of the developed technology to meet the Navy�s needs through material testing. The Phase I Option, if exercised, will outline the requirements and specifications to build prototypes in Phase II.
PHASE II: Based on the results of Phase I efforts and the Phase II Statement of Work (SOW), develop the prototype bus bar to meet the Navy�s needs and verify in accordance with MIL-DTL-23928. Mature NDT technology and demonstrate the capability to detect bus bar insulation flaws. Demonstration/verification testing will occur at a company-provided facility. Refine the fabrication process and test procedure with a focus on creating consistent product to aid transition in Phase III. Prepare a Phase III development plan to transition the technology for Navy and potential commercial use.
PHASE III DUAL USE APPLICATIONS: Support the Navy in transitioning the bus bar technology to DDG 1000 class destroyers and future Navy high voltage systems. The final product will be capable of meeting all relevant qualification testing including shock, vibration, electromagnetic interference (EMI), humidity, and temperature. Support the development of documentation including, but not limited to; technical manuals, parts lists, drawings, training guides, and logistics documents.
The use of high voltage distribution systems and electric propulsion is becoming more frequent in the offshore and shipping industries. Reliable bus bars and the ability to verify manufacturing quality will be required to support this expansion. The technology developed to support the Navy is directly applicable to these industries and the shore-side power industry.
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KEYWORDS: Laminated Bus Bar; High Voltage Insulation; High Voltage Connectors; Shipboard Power Distribution; Partial Discharge Testing; Non Destructive Testing.