Page 28: of Maritime Reporter Magazine (September 2003)

flux densities and gap shear stresses generated by the superconducting field coils, HTS motors follow fundamentally different scaling laws than do conven- tional motors. HTS motors scale according to a 1/5 (0.2) power rule instead of the conventional 1/3 (0.3) power rule. This means that very high horsepower HTS motors are not much bigger than more moderate-sized HTS motors. For example, a 25-MW 120- rpm will be only 1.4 times dimensional- ly larger than AMSC's 5-MW HTS motor, despite having five times the power and ten times the torque of the

Figure 3 The 36 5 sma"cr machine. Replacing the diesel

MW HTS marine w't'1 a §as turbine will remove the propulsion motor design limitations created by the diesel uses technology vali- engine's great size and weight, dated in the U.S. HTS technology also greatly improves

Navy's 5-MW Motor today's electric ship propulsion systems. merts63'116' Consider the conversion to electric propulsion of the Queen Elizabeth 2 in 1987. The electric propulsion modifica- tion designers were constrained by the existing engine room layout and volume in which they could install, leading to the selection of two 44-MW 150-rpm synchronous pancake motors. Each weights about 400 cu. tons and measures about 29.5 ft. (9 m) in width and height and about 20 ft. (6 m) in length. Each motor is so large, and the ship's installa- tion restrictions so severe, that each was built, delivered and installed in quarters — two half stators and two half rotors.

The motors and the other ship's electric- ity needs are met by nine 10.5-MW medium speed conventional diesel gen- erator sets with a total weight of more than 2,000 tons.

Conversion of the QE2 to electric drive was a remarkable achievement.

The installation has worked well and the ship continues to operate today as the premier transoceanic cruise ship of our

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