This challenging Platinum Mine 15MW stator and rotor rewind project represents a significant achievement in motor refurbishment and showcases meticulous attention to detail and adherence to industry standards. Awarded to Marthinusen & Coutts (M&C) in late November 2024, this project involved a comprehensive overhaul of a motor that had been in service for over 18 years. M&C was awarded this contract due to their proven, successful repairs and their intricate knowledge of the design of these 15MW motors.
Project Objectives and Scope
The primary objective of the rewind project was to restore the motor to the same high standards as when it was initially manufactured. This ambitious goal required a thorough scope of work, including:
· Rewinding the stator and rotor, incorporating steel binders into the rotor windings – a complex and very difficult task to execute
· Overhauling the brush gear compartment and installing new brushes
· Re-insulating the slip rings with new insulation material
· Installing new heat exchangers
· Conducting shaft repairs and fully refurbishing the white metal bearing assemblies
· Dynamically balancing the rotor
· Skimming the stator feet and pedestal bearings
· The complete assembly of the motor
· Finally, a no-load test run was performed, and the motor was repainted to complete its restoration.
Technical Challenges and Solutions
The rewind process proved challenging, especially concerning the use of steel binders on the rotor. M&C engaged an expert craftsman with 35 years of experience in fitting these complex components. The project’s complexity required precautionary measures during critical stages, including the burnout, coil manufacturing, VPI (Vacuum Pressure Impregnation), and curing cycles, as well as balancing to ensure the rotor met a tolerance of G 0.4.
In selecting materials for the rewind, M&C chose a comprehensive insulation solution in consultation with M&C’s international insulation experts.
Project Management and Compliance
To keep the project on schedule, M&C adopted a proactive approach, though some delays occurred due to the complexities of the VPI processes. The project management methodology included clearly defined hold points, as requested by the customer. M&C’s Quality Control (QC) department regularly communicated with the customer, providing updates when hold points were ready for inspection.
Safety was the highest priority throughout the rewind process. Senior operators and technicians carefully supervised testing and lifting procedures, ensuring compliance with industry standards and regulations. Compliance with various testing standards - established by both the International Electrotechnical Commission (IEC) and M&C’s internal standards - was maintained throughout the project.
Collaboration and Communication
Effective coordination with the customer was maintained by compiling weekly progress reports and holding regular meetings that adhered to the outlined project timeline. Notably, the customer engaged an independent third-party specialist to verify and sign off on all hold points, further enhancing the project’s transparency and credibility.
Looking Ahead
Looking ahead, M&C expects major advancements in the repair and maintenance of motor components. Key enhancements will likely focus on improving mechanical conditions and reconditioning motor and pedestal bases, thereby increasing the lifespan and efficiency of vital equipment.
It is evident that M&C’s dedication to quality workmanship and customer satisfaction is unwavering. M&C successfully extends the lifespan of these 15MW machines and, as experts, offers solutions for customers, making them the repairer of choice.