Modernization & Life-Time Extension
EthosEnergy has developed and implemented modernizations of generator stators with power up to 600 MW, these contain a wide variety of innovative and verified in practice design solutions.
There are many types of generators operating globally, made by different producers, differing in size and power, design, cooling system (e.g. direct, indirect, hydrogen, air, water), technical and operational conditions, which means every stator prior to its modernization requires individual analysis. These details coupled with customer needs and other requirements have an effect on the final scope of the stator modernization.
When modernizing generators, we put great emphasis on reducing the temperature increases of all active components, we use the best solutions which provide effective, reliable and failure-free operation. We manufacture stator winding in ResinRich technology, of high temperature index, with the main insulation continuous over the full length of the bars (applied with an automatic insulating machine), with inner and outer corona protection in slot and end-winding parts, with optimized configuration of solid and hollow copper conductors on the bar cross-section and with optimal configuration of Roebel transpositions. We connect the winding bars with reliable connectors providing effective electric contact and water tightness – if necessary (e.g. with spherical connectors).
We equip stators with an effective system of wedging of stator winding in core slots, extending the time period between possible rewedgings, as well as an effective system of end-winding suspension providing adequate rigidity for different loads (so-called radial-rigid axial-free system) effectively limiting the machine vibrations, especially in the frequency range of 100 and 120 Hz. We also offer end-winding stability systems that can be installed to existing end windings without removal of stator coils – this is highly recommended when winding instability is diagnosed. The external part of the generator stator is a monolithic frame made of large-size elements providing pressure resistance, gas tightness and explosion-proof safety. Stator core stacks during their assembly are effectively pressed using thermal-vibratory method. The end stacks are designed to limit their additional heating. The stator can be equipped with a maintenance-free core pressing system using a spring pressing Belleville end-plates providing constant pressing forces to the core during operation, as well as a flexible core suspension system that limits core-to-frame vibration transfer.
Stators modernized by us are characterized by significantly improved design and technical parameters, resulting in increased life-time. The final scope of every modernization requires individual analysis, dependent on the individual original design of the machine and the customer requirements.