Active magnetic bearing for a liquid nitrogen pump

The development of a liquid nitrogen submerged pump for HTS applications is underway. A cryogenic active magnetic bearing is the main component of the pump. The bearing makes the maintenance interval of the pump longer than 3years such interval is essential for the pump in commercial use of HTS applications such as long HTS cable. The bearing will be set in a HTS motor shaft of the pump. In experiments, a shaft without an HTS motor is used and the bearing was immersed in liquid nitrogen. The rotation of the shaft is made by a high-speed motor at room temperature. The bearing consists of two radial bearings and one axial bearing. The shaft was floating by the bearing and was rotated by the motor at room temperature. The steady rotation speed of 2,000, 3,000, 4,000 and 5,000 rpm were achieved, and the rotation speed satisfied the design speed of the pump which is 5,000rpm.