JUNE/JULY 2013 | £5.25 - Wind Energy Network

LubricantsLubricantsAdvanced wind turbinegearbox filtration andcondition monitoring systemsOur regular lubricants feature continues to grow and therefore proves howimportant the subject area is to the industry.We welcome Hydac as our sponsors for the next year and they start us off withinformation on advanced filtration and condition monitoring, thus ensuring gearboxhealth.Ensuring gearbox health andavoidance of early failures withadvanced filtration and conditionmonitoring system upgrade kitsA wind turbine gearbox is one of themost important components of a windturbine. The cost of changing a gearboxafter a bearing failure can easily add up to£100,000 and more, which can threatenthe economic success of operating a windturbine. So protecting the gearbox with astate-of-the-art lube and filtration systemis a key factor to a reliable and profitableoperation.Upgrades to High PerformanceFiltrationFor more than 15 years HYDAC havebeen and still are the leading supplier oflube systems and filtration for wind. Basedon the experience in this application andon testing and R&D studies, the filtrationconcepts and products were optimised forthe wind application in several steps.This resulted in the most recent filterelement series BN4HX which is used fornew wind turbine gearbox installations.The BN4HX elements have an increaseddirt holding capacity, high beta ratios anda low differential pressure at high flowrates and high viscosity lubricants.This helps maintain oil cleanliness duringthe whole installation time of the filterelement. The differential pressure remainslower for the lifetime of the filter.This reduces the amount of time withopen filter bypass and without full filtration.Also manyolder windturbine gearboxdesigns canbe convertedto BN4HXfilter elementsto achieve fullprotection for thegearbox usingthis most recenttechnology. Thisincludes therecommendable2-stage designwhere a 50µmfilter providesa minimumfiltrationfor situations with open filter bypass.Analyses of used filters have shown thatthe 50µm stage was helpful becauselarge contaminants, ≥100µm, were foundand were removed by the 50µm-stage.Without the 50µm stage these would havebeen delivered to the lube contacts in thegearbox.Filter size extension kitsThere are various options available, suchas larger filters with the same pore size,providing more filter life-time; these havethe potential to reduce the annual filtrationcost. Also there are upgrade kits withhigher micron ratings providing a highercleanliness level or special filter mediafor removal of non-solid contaminants.There is a 3-stage-filter option whichhas an additional stage with partial flowto combine a filter element with lowdifferential pressure and very fine filtrationin the partial flow situation.Desiccant breatherOlder turbines especially can benefitfrom upgrading to a desiccant breather.The BDE uses a combination of twodesiccants to achieve a high watercapacity and also a high efficiency.Drying the air when the gearbox inhalescontributes to keep the amount ofdissolved water in the oil at a reasonablylow level during operation and stop. Also,a full pleated air filter element for solidcontaminants is included in the BDEbreathers.Offline Filter UpgradesAn addition of new, and an upgrading ofexisting offline filter circuits enables usingthe Trimicron offline filter elements forremoval of fine particles, free water and oilageing bi-products.Oil Condition MonitoringUpgrade KitsFor online monitoring of the gearboxhealth, an oil condition monitoring upgradekit can be installed. HYDAC has variousdata acquisition and analysis systemssuch as the CMU 1000. The sensorsignals can either be transmitted via cablee.g. ethernet or per wireless connection,depending on the local situation. A CMUcan support an array of sensors includinge.g. particle counting, water, differentialpressure, temperature and other signalsas required.Such a data acquisition system islocated in an additional electrical cabinet.Also measured data from a specificwind turbine can be transmitted perSMS message either on request, or ifPhoto by ABO Wind AGwarning levels are exceeded. Hence, anoptimisation of maintenance planning forthe service personnel is provided andoperation time in damaging operatingconditions is minimised. Additionally,HYDAC can offer a remote access,network connected solution with thecondition monitoring package CM Expert.Sensor arrayThe sensor array typically includes particlemonitoring for wear debris with sensorsof the MCS 1000 series. The MCS1510 wear debris monitor can easily beintegrated to the inline lubrication circuit ina full flow configuration with many existingturbine designs.By analysing the number and rate ofparticles in the oil flow, an early detectionof failures is achieved.The AS 1000 sensor can be added formonitoring the water content in the oil.This helps identification of problems withthe water content before the effects (oilsludge, corrosion, bearing fatigue) occur.GW Filter Condition MonitoringThe GW sensor is easy to install to a filterhousing. This allows detection of situationswith reducedfunction of the lubeand filtration circuitsuch as open filterbypass, improperflow rate, false orcontaminated filterelement, incorrectsystem pressureand more.SummaryWind turbinestypically have20 years designlife. Changingthe gearboxprematurely dueto a bearingfailure and wear of a wind turbine gearboxneeds to be avoided. When the gearboxlifetime is reduced, for example to 9 years,2 changes will be necessary within the20 years. Hence, the gearbox needs torun as long as possible and rewards themost recent technology as a protection toremove solid contaminants.Dr. Armin Schmidt & Tobias Daley Hydacwww.hydac.co.ukClick to view more info80 www.windenergynetwork.co.ukwww.windenergynetwork.co.uk 81