November 2014 | Railway Gazette International 64 PASSENGER TRAINS Diagnostics SJ embraces remote bearing monitoring JUSTIN SOUTHCOMBE Commercial Director Perpetuum Ltd W ith SJ facing competition on its busiest inter-city corridor from next March (p55), the operator has launched a mid-life refurbishment programme to update its 43 SJ2000 tilting inter-city trains. One novel aspect of the work is the installation of 40 sets of Perpetuum’s bearing and wheelset monitoring equipment on both powered and trailer wheelsets. At the heart of this technology is a novel vibration harvester, which converts vibration into a reliable electrical energy supply. It was developed by academics at the University of Southampton, who established Perpetuum in 2004 as a means to commercialise their research. Although initially targeted at the industrial sector, the harvester later found a more compelling application in the high-vibration railway environment. For the last four years, Perpetuum has been developing self-powered sensors that can be mounted directly onto bogie components, and a set of algorithms that can drive condition-based maintenance programmes. Early adopter As reported in RG 9.13 p75, Perpetuum received its first major order from UK operator Southeastern, which was keen to ensure its maintenance teams had accurate information on the status and remaining life of the components. Southeastern fitted Perpetuum’s wireless Sweden’s national operator is deploying Perpetuum’s novel vibration harvesting technology to improve wheelset reliability on its SJ2000 inter-city fleet, which is now being refurbished. Above: SJ’s X2000 tilting train fleet is going through a mid-life refurbishment. Inset: A Perpetuum wireless bearing sensor as fitted to a Bombardier EMU operated by Southeastern in the UK. 20 min TIME TO INSTALL A WIRELESS BEARING MONITORING SENSOR sensors to more than 600 vehicles within three months, thanks to the 20 min fitting time per sensor. Subsequently, Southeastern has received safety case approval to introduce a condition-based maintenance regime for axle bearings which should deliver seven-figure sums per year in maintenance efficiencies. SJ’s adoption of the technology comes as a result of an extensive investigation into the level of work needed to ensure the SJ2000 is fit for purpose for the next several years. The operator is looking to reduce operating costs by extending wheelset overhaul period beyond its current scheduled limit, partly because it believes that a small proportion of the vehicles in the fleet is responsible for a perception of short wheelset life and a lack of component reliability. The various different maintenance regimes, sub-assemblies and operating patterns over the past 20 years have compounded the problem of fully understanding the variances in bearing life across the different vehicles. As wheelset overhaul is being driven by the unpredictable performance of the bearings, it follows that by monitoring the bearing condition SJ should be able to run the trains safely until a change in vibration condition passes the calibrated threshold. Perpetuum expects its analysis tool to spot this breach three months before any non-vibration based monitoring device. We are currently at the calibration stage where algorithms are tuned for the specific fleet, operating conditions and components, to ensure that the Bearing Health Index is 100% reliable. For the SJ contract, Perpetuum has taken additional measures to protect the sensors in harsh winter conditions, which can include snow compacting, ice formation and frozen ballast strikes. Perpetuum has developed a poly-composite casing, manufactured from the same PEX material used to protect the SJ2000 axles. The casing has been designed with two key targets in mind: a reduction in the risk of higher moments on the bearing cover sensor brackets, and the shielding of the 433 MHz data transmission from the sensor. The sensors were subjected to -30°C under high accelerated life testing conditions, designed to destroy the components, and they performed very well. The antenna was also encased in ice to test the communications from the sensors to the onboard data concentrator, with no significant loss in performance being recorded. Perpetuum has found its experience in exporting UK technology to Scandinavia to be very positive, with the local industry willing to embrace condition-based maintenance and remote condition monitoring. But if this year’s InnoTrans show was anything to go by, there is the real prospect of uptake from other large railways around the world, including those in China, India, Russia and South Korea. n
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