Engine & Turbine Technology
Vibration measurements obtained from various positions on the gearbox (e.g. input shaft, intermediate shaft and output shaft) are often the best approach in enabling any damage to the bearings or gears to be detected.
Case study In a recent operational test of a wind turbine gearbox, a 1.2MW gearbox was run at 1,500rpm on a purpose-built test stand under a range of operating conditions. Vibration measurements were taken at various positions on the gearbox housing. T e vibration spectrum was obtained
from the housing close to the high speed shaft (HSS). T e calculated BPFI (Ball Pass Frequency of the Inner ring) for the type NU228 cylindrical roller bearing on the HSS was 271.26Hz and present in the spectrum is a large amplitude vibration at 270.64Hz, which matches very closely with the calculated frequency. Either side of the vibration at 270.64Hz are a few sidebands at shaft rotational speed (fs=25Hz). In the envelope spectrum, the BPFI is also evident at 272.50Hz, along with the
third harmonic (817.52Hz). T is indicates that some damage may be present on the inner ring raceway and the absence of any signifi cant harmonics of BPFI suggests that the damage is fairly localised. T is is further supported by the impulsive nature of the time signal that shows impulses at the output rotational speed (40ms, 25Hz).
V
ibration monitoring can be used to assess the condition of drivetrain components prior to installing these on the wind turbine.
As a result of these tests, the gearbox was stripped down and examined. A localised fault was discovered on the inner ring raceway of the type NU228 cylindrical roller bearing. T is damage occurred during the assembly process – the most likely cause being misalignment between the inner ring and outer ring/rollers as the inner ring-shaft and outer ring-housing were aligned and assembled together. During running of the gearbox on the test stand, all the operating temperatures
Rapid power sector demand drives automation and control systems development in Indonesia
W
ith key industries across Indonesia facing a growing demand for their products
and services, the need for automation and control systems to maximise capacity utilisation is on the rise. The booming power and infrastructure sectors, in particular, will be looking to automate further to optimise their systems by eliminating or reducing wastage. New analysis from Frost & Sullivan, The
Indonesian Automation and Control Market, finds that the market earned revenues of US$175.6 million in 2014 and estimates this to reach US$239.1 million in 2018. The study covers the programmable
logic controllers (PLC), supervisory control and data acquisition (SCADA), distributed control systems (DCS), human machine interface (HMI), and safety systems product segments for various end-user industries, including power. The renewable energy sector, which is forecast to meet over 30% of Indonesia’s
energy needs in 2050, is a lucrative space for automation vendors. In order to reduce costs due to oil
imports, the Government has started to raise fuel and power prices and institute financial incentives to promote the development of alternative sources of energy, indicating the vast potential this sector has to offer for automation vendors in the country. “Strong opportunities will emerge
for automation vendors, with robust regulatory practices and a focus on smart cities set to make geothermal energy the largest renewable energy source,” said Frost & Sullivan Industrial Automation & Process Control Research Analyst Krishnan Ramanathan. “As geothermal energy grows in popularity, automation and control systems will be required for effective asset management and the protection of green energy investment.” The power industry will also
significantly impact the development of the automation industry in Indonesia, with the
Government’s plans to boost the installed capacity from 1,340 megawatts (MW) in early 2014 to 6,500 MW by 2025. As renewable energy can bring off-grid
power to households that have no access to electricity or rely on costlier options, it will play an important role in meeting the country’s power requirements and drive the need for automation and control systems. “Additionally, the Indonesian
Government expects the infrastructure, manufacturing and mining sectors to continue to attract investments and fuel the demand for automation and control systems,” noted Ramanathan. “While there is uncertainty surrounding several regulations and a lack of coordination between the central, provincial and regional Governments to improve the investment climate in the mining industry, companies are unlikely to be discouraged by this and will adopt automation and control systems.” ●
For more information, visit
www.frost.com www.engineerlive.com 29
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