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Within the cooperation between American Superconductor Corporation (AMSC) and Siemens Corporate Technology we have investigated the fault current limiting performance of YBCO-coated conductors (also called second-generation or 2G HTS wires) stabilized with stainless steel laminates. Design rules for the length and width of the wire depending on utility grid requirements have been established. Bifilar coils have been manufactured and tested with a typical limitation period of 50 ms under stepwise increasing voltage loads to determine the maximum temperature the wires can withstand without degradation. Coils have been assembled into limiter modules demonstrating uniform tripping of the individual coils and recovery within seconds. At present this cooperation is proceeding within a joint project funded by the US Department of Energy (DOE) that encompasses the design, construction and testing of a 115 kV FCL for power transmission within a time frame of 4-5 years, and additional partners. Besides AMSC and Siemens, Nexans contributes the high voltage terminations and Los Alamos National Lab investigates the ac losses. Installation and testing are planned for a Southern California Edison substation. The module planned for the transmission voltage application consists of 63 horizontally arranged coils connected in parallel and series to account for a rated current of 1.2 kA rms and voltage of 31 kV rms plus margins. The rated voltage of the module is considerably lower than the line to ground voltage in the 115 kV grid owing to our shunted limiter concept. The shunt reactor connected in parallel to the module outside the cryostat allows for adjustment of the limited current and reduces voltage drop across the module in case of a fault. The fault current reduction ratio is 42% for our present design. A subscale module comprising six full-size coils has been assembled and tested recently to validate the coil performance and coil winding technique. The module had a critical current of 425 A DC and a nominal power of 2.52 MV A at 77 K. A complete series of tests with applied voltage up to 8.4 kV rms , prospective short circuit current up to 26.6 kA rms and variation of phase angle at initiation of the fault has been performed. After more than 40 switching tests the critical current of the module remained unchanged, indicating that no degradation of the wire occurred.

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The development of ship propulsion synchronous motors with high temperature superconductor (HTS) field windings for Naval electric ship applications has progressed to the point where a full scale motor is now under construction. A 5 MW, 230-rpm prototype ship propulsion motor was built and tested by the Center for Advanced Power Systems (CAPS) on behalf of U.S. Office of Naval Research (ONR). It met or exceeded all its design goals. Currently, a 36.5 MW, 120-rpm ship propulsion motor is being built for delivery to ONR at the end of 2006. This paper presents test results of the 5 MW motor and the status of the 36.5 MW motor. Index Terms--ONR (U.S. Office of Naval Research), PWM (pulse width modulation), COTS (commercial-off-the-shelf), 1G (first generation (BSCCO) HTS wire), 2G (second generation (YBCO) HTS wire), VSD (variable speed drive)

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