FEATURE ENERGY EFFICIENCY
As energy consumption increases so does the need for improved efficiency as well as new sources of energy. David Hardy, commercial manager at Sulzer’s high voltage coil manufacturing facility, looks at how power station operators can improve the efficiency and reliability of the existing generator base
o meet increasing energy demands new facilities need to be installed but
the existing generating equipment also needs to be more efficient and reliable. For the majority of power stations a fuel source is used to produce steam, which is passed through a gas turbine, which turns a generator. In fact, in 2008, over 89% of the world’s energy was produced using this combination and a great deal of that generating capacity was installed over 20
TURBINE GENERATOR REPAIR T
GENERATOR REPAIRS In some cases the full extent of a repair does not become apparent until the generator is removed and examined closely. While the stator coils will usually be replaced, there may also be an issue with the laminated core and the rotor assembly. Modern insulation technology allows for thinner layers which can withstand greater dielectric stress and higher temperatures, which also allows more space for copper within the same slot area. This reduces the resistance of the stator winding, which runs cooler, allowing a small increase in output. By using the latest CAD software, the
analysis, which can indicate potential problems with bearings, and large rotating parts - combined with thermal imaging that is used to identify potential issues with bearings, poor electrical connections or the imbalance of phase loadings, which can produce an accurate indication of the overall status of the plant. Additional testing of the electrical
years ago. Since then, technological advances in turbine and generator design have made great improvements in efficiency which could now be retro-fitted in a proactive maintenance programme. A power station needs to optimise output to meet demand, but inevitably there comes a time when maintenance repairs, either electrical or mechanical, will be required. While this may not affect the ability of the power station to meet current demand, it will place increased pressure on the remaining capacity, which in-turn needs to be robust enough to cope. Therefore, a programme of periodic, preventative maintenance can be combined with condition monitoring techniques to improve the reliability of the equipment.
CONDITION MONITORING Employing a range of condition monitoring equipment, combined with suitable analysis techniques, can provide an accurate assessment of the status of turbines and generators, allowing operators to ensure continued production. One of the most useful tools is vibration
12 JUNE 2014 | ELECTRICAL ENGINEERING
Above right: Sulzer is a provider of engineering solutions for the power generation sector, from ongoing condition monitoring to complete turnkey projects
Above: using the latest CAD systems, precise quality control and extensive testing, modern coil production can improve the performance and efficiency of any generator which is due for refurbishment
Right: damaged turbine blades must be replaced, new bearings sourced and installed and the completed assembly carefully balanced to ensure smooth running once it is reinstated
windings, especially partial discharge (PD) analysis, can also provide very useful information on the overall condition of the generator. PD can cause insulation degradation, which if not remedied, can lead to reduced output of the generator. The appropriate use of condition monitoring provides an excellent maintenance tool and can ensure efficient generator output.
TURBINE REPAIRS Once a turbine has been removed, it is essential to complete the inspection and assessment process as soon as possible in order to prepare the reconditioning proposal. The ability to carry out weld inspection down to a microscopic level and provide accurate analysis of the balance of the turbine is important in determining potential areas for improvement. Delivering high levels of maintenance is essential, meaning any issues must be repaired to precise standards using the appropriate techniques according to the turbine specification. Damaged turbine blades must be replaced, new bearings sourced and installed and the completed assembly carefully balanced to ensure smooth running once it is reinstated.
bars or coils can be precisely formed to ensure an exact fit in the stator slot, making the installation process more efficient. By using comprehensive testing techniques, the reliability of the new coils can be guaranteed, which is especially important for coils being used in hydro generators, which can be required to pass a 400 hour voltage endurance test to provide evidence of the build quality of the coils. Sulzer has developed a large network of service centres capable of completing turbine repairs as well as employing experienced engineers, equipped to complete projects on-site if necessary. The high voltage coil manufacturing
facility, based at the company’s Birmingham Service Centre, employs an in-house copper rolling mill to enable round-the-clock coil production. Using the latest CAD systems, precise quality control and extensive testing, modern coil production can improve the performance and efficiency of any generator which is due for refurbishment.
Sulzer
www.sulzer.com T: 0121 766 6333
Enter 204
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