Test Field for Magnetic Bearing Applications Under Extreme Conditions

Active magnetic bearings (AMB) are an essential key technology in modern power plant concepts. The application of AMBs in turbo machines (steam turbines, cooling pumps and compressors) is characterized by extreme process and environmental conditions like high temperatures, corrosive fluids and gases. Especially the use of organic materials limits the insulation level of electromagnetic actuators. Currently the allowed maximum continuous temperature of coils and laminated cores is 160C. Known solutions like ceramic insulation systems allow actuator temperatures up to 450C. But their production is complex and the specific actuator size increases compared to conventional insulated actuators. The development of new surface technologies and advances in material science allow new basic approaches for insulations and thereby for High Temperature Active Magnetic Bearings (HTAMBs). For instance the use of the physical vapor deposition technology (PVD) allows low cost coatings with thicknesses of only a few micrometers. Furthermore, the fusion of AMBs with catcher bearings (CB) to an integrated unit is advantageous for a compact machine design. It is one objective to place the bearing units close to the process section, if appropriate into the process section. So the CBs also have to fulfil their functions under extreme conditions.