Bridge crane certification – The first job was to ensure that the bridge crane that would be used to disassemble the machine and to extract the generator’s 290-ton rotor was certified with a 380-ton hoisting capacity. That required load-testing the bridge crane in the presence of owner-certified and approved third-party testers.
Coil production – Because the original manufacturer’s documentation was unavailable, Nidec used a spare sample to conduct a three-dimension laser reconstruction of the coil. To achieve a 10% power increase, Nidec engineers improved the insulation materials and made other changes to optimize the existing design. Over a three-month period, the company then produced 425 resin rich coils.
Stator rewinding – To speed up the turbine’s reconnection to the grid, the rewinding process was completed on an aggressive 2.5-month schedule. During that time, Nidec professionals disassembled the machine, extracted the 290-ton rotor and dismantled the existing stator winding. Then, after performing cryogenic cleaning on the stator coil, all the new coils connected in the original winding scheme. The company’s work also included overhauling, testing, cleaning and painting the rotor and replacing the existing rotating exciter with a new static exciter.