High-Temperature Superconducting Motor Could Reduce Energy Losses

Industries and the US Department of Energy (DOE) are increasingly interested in the potential advantages of superconducting motors as energy demands and energy costs continue to escalate. About 33% of electrical energy generated in the United States is used to power motors rated 1,000 hp and above. Because superconducting motors will be smaller, lighter, and more efficient than conventional motors, they would likely be used in applications where large motors run continuously, including utilities and petrochemical applications. They also may be used in applications where the size and weight of the motor are critical, e.g., shipboard propulsion.

Figure 1. The 2-hp High-Temperature Superconducting (HTS) Motor, shown here during testing, has 2G wire and coils. The temperature inside the rotor of the superconducting motor is about -312°F, which is cold enough for the wire to show its superconductive properties.
Figure 2. This Comparison Demonstrates the Size Difference between a conventional 400-amp copper wire (right) and a piece of 2G, 400-amp superconducting wire.

Rockwell Automation, in cooperation with the DOE’s Superconductivity Partnerships with Industry (SPI), successfully demonstrated the capabilities of a 2-hp, Reliance Electric, high-temperature superconducting (HTS) motor with second-generation (2G) HTS wire and coils. This recent test (see Figure 1) followed an earlier proof-of-concept test, and is a key benchmark toward the commercialization of super-efficient, highhorsepower motors designed to potentially reduce energy losses by half.

Operation

The demonstration utilized the new HTS ceramic-based, 2G, coated conductor wire, marking the first time 2G wire had been used to create coils large enough for a 2-hp electric motor. The motor utilized 14 meters of wire, wound into two rotating field coils. The 2G HTS wire demonstrated superior performance over commonly used first generation (1G) HTS wire (see Figure 2), and is an essential component for a cost-effective industrial HTS motor.

The liquid nitrogen used to cool the HTS coils in the motor was introduced into the center of the rotor and then the nitrogen gas was exhausted through the motor frame. The temperature inside the rotor was about -321°F (cold enough for the wire to show its superconductive properties).

In large industrial HTS motors the superconducting coil coolant will be recaptured from the rotor and rechilled in a closed-loop cooling system so that no cold gas or liquid escapes from the motor.

More Information

For more information, contact Shawn Traylor, Rockwell Automation Power Systems, Greenville, South Carolina, at (864) 281- 2171 or smtraylor@powersystems.rockwell.com. Visit Rockwell Automation online at http://info.ims.ca/5292-332. For more information on 2G HTS wire, visit Super- Power, Inc., Schenectady, New York, (a subsidiary of Intermagnetics General Corp.) at http://info.ims.ca/5292-333.