Engine & Turbine Technology
manager Stephen Gilbert. “So when we noticed that the alternator was becoming heavily contaminated, it raised some concerns. As it has been running pretty much non-stop since 2003, we opted to raise a tender for its total overhaul. In fact, this idea was first recommended to us by a visiting Leroy-Somer technician during a visit in 2013.” Although in very good condition, the alternator had already run for 71,000 hours, with experience suggesting that an overhaul every 40,000 running hours pays dividends in terms of performance and efficiency. In 2016, Newlincs decided it should wait no longer and scheduled a major overhaul. Leroy-Somer, which was among the bidders for the tender, dispatched a technical expert from its Orléans factory, where the machine had been manufactured, to evaluate the project and provide further recommendations. “Te key factor in this project was
turnaround time,” says Gilbert. “We had a limited and strict three-week window of downtime in which the system would need to be uninstalled, overhauled, refitted and recommissioned – without fail. We liked the idea of using the alternator OEM for the overhaul as this introduces confidence into the process, along with a high level of expertise. Tey also had an interesting proposal regarding the location of the overhaul.”
UK overhaul carried out in France Leroy-Somer offered to perform the overhaul in Orléans, which although at first may seem counter-intuitive, in fact makes full sense. Te Orléans factory is equipped with efficient vacuum pressure impregnation (VPI) equipment, guaranteeing high-quality windings, as well as a fully operational test bench that can perform on-load measurements. Furthermore, all steps of the process would be performed by experts who build alternators on a daily basis. “If you consider the project in its
entirety,” explains Eric Delabarre, service engineer at Leroy Somer, “transportation is neither the biggest challenge nor a decisive cost centre. It’s everything that happens in- between that’s important: on-site removal, workshop impregnation and testing, and final commissioning. Using factory equipment allows us to provide the best
possible service at an affordable cost, all with very good turnaround times.”
All-inclusive service Based on its proposal, Leroy-Somer won the tender for an all-inclusive service from on-site shutdown to on- site recommissioning. Commencing the process, vibration and electrical measurements were taken on the alternator before de-commissioning for reference. Te machine was then shut down, de-coupled from the turbine, disconnected and prepared for transportation. Removing the turbine and alternator required cutting open the plant room roof and lifting out the equipment using a 200 tonne crane. Te generator was then shipped to Orléans by Leroy-Somer, where it underwent overhaul operations. Following disassembly and inspection, the windings were thoroughly cleaned and steamed, and underwent impregnation to renew varnish on the coils. Te terminal box was also fully cleaned and all connectors tested. After re-assembly, the complete alternator was tested on the factory bench, with electrical performance compared against initial tests performed
in 2003. Te overhauled alternator was then shipped back to the UK and re-commissioned, where it showed the same performance level as when it was manufactured 15 years earlier. “Te alternator returned on-schedule
and worked first time following reinstallation and recommissioning,” confirms Gilbert. “We’ve had no issues at all with its performance since the overhaul, which is essential as we require the generator to run for 8000 hours a year, producing electricity for the whole site as well as 2.5MW for export.” In May 2017, exactly one year after the alternator re-commissioning, the Leroy-Somer service team was back at the Newlincs site for a yearly health check of the system. Te test routine to check mechanical and electrical indicators led to the detection of a potential problem on the diode bridge, which in turn could have led to a general failure and shutdown of the whole installation. As a preventive maintenance measure, a new diodebridge was ordered and installed on the generator. Te team will return to site on a yearly basis to produce a report on operating condition. l
Transportation was not the biggest challenge in this project
www.engineerlive.com 31
Page 1 |
Page 2 |
Page 3 |
Page 4 |
Page 5 |
Page 6 |
Page 7 |
Page 8 |
Page 9 |
Page 10 |
Page 11 |
Page 12 |
Page 13 |
Page 14 |
Page 15 |
Page 16 |
Page 17 |
Page 18 |
Page 19 |
Page 20 |
Page 21 |
Page 22 |
Page 23 |
Page 24 |
Page 25 |
Page 26 |
Page 27 |
Page 28 |
Page 29 |
Page 30 |
Page 31 |
Page 32 |
Page 33 |
Page 34 |
Page 35 |
Page 36 |
Page 37 |
Page 38 |
Page 39 |
Page 40 |
Page 41 |
Page 42 |
Page 43 |
Page 44 |
Page 45 |
Page 46 |
Page 47 |
Page 48 |
Page 49 |
Page 50 |
Page 51 |
Page 52
