MORE FREQUENT FAULTS IN AGING TRANSFORMERS<\/h2>\n
The bath\u00adtub curve is a mod\u00adel for describ\u00ading the sus\u00adcep\u00adti\u00adbil\u00adi\u00adty of equip\u00adment to fail\u00adure over its entire ser\u00advice life. Just after com\u00admis\u00adsion\u00ading, the fail\u00adure rate is very high. Once the ini\u00adtial prob\u00adlems have been fixed, the fail\u00adure rate drops rapid\u00adly and hov\u00aders at a con\u00adstant\u00adly low rate. For a long peri\u00adod of time, this doesn\u2018t change. But as the sys\u00adtem gets old\u00ader, the prob\u00adlems start to stack up again after a cer\u00adtain point. If you rep\u00adre\u00adsent\u00aded this trend as a graph, with time along the X\u2011axis and the fail\u00adure rate along the Y\u2011axis, the curve would look some\u00adthing like the cross-sec\u00adtion of a bath\u00adtub.<\/p>\n\n But what Linossier and Funk have been rack\u00ading their brains over is the fol\u00adlow\u00ading: At what point of the bath\u00adtub curve are their trans\u00adform\u00aders cur\u00adrent\u00adly at? When does the fail\u00adure rate start to climb again? \u201eThat is the point at which we should be arrang\u00ading a replace\u00adment,\u201c says Mr. Funk, who spe\u00adcial\u00adizes in strate\u00adgic asset man\u00adage\u00adment for pow\u00ader trans\u00adform\u00aders. Since the aver\u00adage age of trans\u00adform\u00aders at RNG is 45.7 years, this ques\u00adtion is becom\u00ading increas\u00ading\u00adly press\u00ading. Most of these trans\u00adform\u00aders were com\u00admis\u00adsioned back in the 1950s and 1960s. The deci\u00adsion to replace these trans\u00adform\u00aders not only has tech\u00adni\u00adcal ram\u00adi\u00adfi\u00adca\u00adtions, but also has finan\u00adcial con\u00adsid\u00ader\u00ada\u00adtions as well, since a new pow\u00ader trans\u00adformer of this scale would cost almost half a mil\u00adlion euros. \u201ePre\u00advi\u00adous\u00adly we would sim\u00adply replace the trans\u00adform\u00aders with new ones after a cer\u00adtain amount of time, but the cost pres\u00adsures today are much high\u00ader. For this rea\u00adson, we want to get the most out of the equip\u00adment for as long as pos\u00adsi\u00adble,\u201c says Mr. Linossier.<\/p>\n \u201eThere are trans\u00adform\u00aders used in indus\u00adtri\u00adal fields which have to replaced after 15 years of usage, and then there are those which only oper\u00adate at 30 per\u00adcent load and have been in oper\u00ada\u00adtion for over 50 years already. So the transformer\u2018s age alone doesn\u2018t nec\u00ades\u00adsar\u00adi\u00adly say any\u00adthing about its con\u00addi\u00adtion.\u201c And RNG isn\u2018t the only oper\u00ada\u00adtor with a fleet of aging trans\u00adform\u00aders: In the two decades fol\u00adlow\u00ading the Sec\u00adond World War, the demand for more and more elec\u00adtric\u00adi\u00adty increased rapid\u00adly. New pow\u00ader plants were built, cables were laid, and numer\u00adous pri\u00adma\u00adry sub\u00adsta\u00adtions were erect\u00aded. Huge swaths of the Ger\u00adman elec\u00adtric\u00adi\u00adty grid today are still based on the plans drawn up dur\u00ading this time. And this was not lim\u00adit\u00aded to Ger\u00admany, but was rather a phe\u00adnom\u00ade\u00adnon of all mod\u00adern indus\u00adtri\u00adal nations. That said, the net\u00adwork load fore\u00adcasts at the time were much dif\u00adfer\u00adent.<\/p>\n \u201eWith the increas\u00ading use of renew\u00adable ener\u00adgies, grid struc\u00adtures need to be com\u00adplete\u00adly redesigned and it\u2018s there\u00adfore very impor\u00adtant that we know the exact con\u00addi\u00adtion of our trans\u00adform\u00aders,\u201c stress\u00ades Mr. Linossier. On the one hand, because the uti\u00adliza\u00adtion of the trans\u00adform\u00aders changes over time and, on the oth\u00ader, because upgrad\u00ading the net\u00adwork will make some instal\u00adla\u00adtions redun\u00addant in the future. \u201eIf we replace the trans\u00adform\u00aders too ear\u00adly, that could turn out lat\u00ader to be a bad invest\u00adment,\u201c adds Mr. Funk. At present there is no method for assess\u00ading the exact con\u00addi\u00adtion of the trans\u00adformer fleet.<\/p>\n How\u00adev\u00ader, all this is set to change thanks to a chance encounter in a tram in Lyon. Alex\u00adei Babiz\u00adki, Port\u00adfo\u00adlio Man\u00adag\u00ader at MR and Markus Zdrallek, a pro\u00adfes\u00adsor at the Uni\u00adver\u00adsi\u00adty of Wup\u00adper\u00adtal, got into a chance con\u00adver\u00adsa\u00adtion on the way to the air\u00adport, both hav\u00ading just attend\u00aded the same con\u00adgress. Zdrallek holds the senior pro\u00adfes\u00adsor\u00adship for elec\u00adtri\u00adcal ener\u00adgy sup\u00adply tech\u00adnol\u00ado\u00adgy<\/a> and has been work\u00ading on the con\u00addi\u00adtion assess\u00adment of equip\u00adment in elec\u00adtric\u00adi\u00adty grids for many years. \u201eWe want to offer grid oper\u00ada\u00adtors a sci\u00aden\u00adtif\u00adic basis for intel\u00adli\u00adgent net\u00adwork renew\u00adal strate\u00adgies,\u201c says Mr. Zdrallek, \u201ebut pow\u00ader trans\u00adform\u00aders have not yet been exam\u00adined in my research.\u201c<\/p>\n The con\u00addi\u00adtion of the trans\u00adform\u00aders is exam\u00adined in up to three stages, which can reduce the required down\u00adtime of the trans\u00adform\u00aders:<\/p>\n 1<\/span> In the first stage, the oper\u00ada\u00adtor pro\u00advides the data which is already avail\u00adable<\/strong>. This includes, for exam\u00adple, the age of the trans\u00adform\u00aders, mea\u00adsure\u00adments that have already been car\u00adried out, and main\u00adte\u00adnance his\u00adto\u00adry infor\u00adma\u00adtion.<\/p>\n 2<\/span> The sec\u00adond stage involves an on-site appraisal<\/strong> which is car\u00adried out while the trans\u00adform\u00aders are still in oper\u00ada\u00adtion. In the visu\u00adal inspec\u00adtion, an expert uses a check\u00adlist to exam\u00adine the trans\u00adformer based on its exter\u00adnal char\u00adac\u00adter\u00adis\u00adtics: Are there any signs of cor\u00adro\u00adsion or leaks? Is there vis\u00adi\u00adble dam\u00adage to the bush\u00adings or fans? How old is the motor-dri\u00adve unit? For the mea\u00adsure\u00adments, ther\u00admo\u00adgraph\u00adic tests are per\u00adformed and oil sam\u00adples are tak\u00aden. 3<\/span> If, after this stage, there are any indi\u00adca\u00adtions of more sig\u00adnif\u00adi\u00adcant dam\u00adage, the third exam\u00adi\u00adna\u00adtion stage will fol\u00adlow. In this stage,exten\u00adsive mea\u00adsure\u00adments<\/strong> are per\u00adformed, includ\u00ading a dynam\u00adic resis\u00adtance mea\u00adsure\u00adment and par\u00adtial dis\u00adcharge mea\u00adsure\u00adment. How\u00adev\u00ader, to car\u00adry out these tests, the trans\u00adformer must be removed from the grid.<\/p>\n The data col\u00adlect\u00aded using this method is eval\u00adu\u00adat\u00aded. The analy\u00adsis is car\u00adried out using the algo\u00adrithm devel\u00adoped at the Uni\u00adver\u00adsi\u00adty of Wup\u00adper\u00adtal in asso\u00adci\u00ada\u00adtion with MR. Then the data is trans\u00adferred into two index\u00ades, with one reveal\u00ading infor\u00adma\u00adtion about life-time wear and the oth\u00ader about the fail\u00adure rate. For the assess\u00adment, the results of the two index\u00ades are trans\u00adferred into one graph\u00adic. The con\u00addi\u00adtion of the trans\u00adformer fleet can thus be visu\u00adal\u00adized sim\u00adply; the more trans\u00adform\u00aders locat\u00aded in the quad\u00adrants near the ori\u00adgin, the bet\u00adter the con\u00addi\u00adtion of the fleet and vice ver\u00adsa.<\/p>\n This imme\u00addi\u00adate\u00adly aroused the inter\u00adest of Mr. Babiz\u00adki, since he was look\u00ading for a sys\u00adtem for deter\u00admin\u00ading the con\u00addi\u00adtion of pow\u00ader trans\u00adform\u00aders. He also knows that this helps pro\u00advide an impor\u00adtant ser\u00advice for MR\u2018s cus\u00adtomers: \u201eIt\u2018s impos\u00adsi\u00adble to give a gen\u00ader\u00adal answer to the ques\u00adtion of how long a trans\u00adformer will last. There are trans\u00adform\u00aders used in indus\u00adtri\u00adal fields which have to replaced after 15 years of usage, and then there are those which only oper\u00adate at 30 per\u00adcent load and have been in oper\u00ada\u00adtion for over 50 years already. So the transformer\u2018s age alone doesn\u2018t nec\u00ades\u00adsar\u00adi\u00adly say any\u00adthing about its con\u00addi\u00adtion,\u201c explains Mr. Babiz\u00adki. He and Mr. Zdrallek quick\u00adly agreed that this would be the ide\u00adal top\u00adic for col\u00adlab\u00ado\u00adra\u00adtion.<\/p>\n \u201eIt is of strate\u00adgic impor\u00adtance for us that we know the exact con\u00addi\u00adtion of our trans\u00adform\u00aders.\u201cJan Patrick Linossier<\/cite><\/p><\/blockquote>\n \u201eWe didn\u2018t have the well-ground\u00aded under\u00adstand\u00ading of trans\u00adform\u00aders we need\u00aded, but we did have exten\u00adsive exper\u00adtise in the devel\u00adop\u00adment of con\u00addi\u00adtion assess\u00adments,\u201c recalled Mr. Zdrallek. The researcher hopes that the project will shed more light on how trans\u00adform\u00aders dete\u00adri\u00ado\u00adrate over time, since he is also inter\u00adest\u00aded in the bath\u00adtub curve. \u201eThe curve is often described in the the\u00ado\u00adret\u00adi\u00adcal lit\u00ader\u00ada\u00adture and has even been proven for some ele\u00adments of elec\u00adtron\u00adics. But I was skep\u00adti\u00adcal of whether the curve even exists for elec\u00adtri\u00adcal grid com\u00adpo\u00adnents, and more specif\u00adi\u00adcal\u00adly for trans\u00adform\u00aders, because nobody has yet man\u00adaged to prove this,\u201c adds Mr. Zdrallek. And thus began the col\u00adlab\u00ado\u00adra\u00adtion between the two part\u00adners. In a series of meet\u00adings and work\u00adshops, they worked togeth\u00ader to devel\u00adop an assess\u00adment sys\u00adtem.<\/p>\n What was still lack\u00ading, how\u00adev\u00ader, were trans\u00adform\u00aders on which they could test their assess\u00adment sys\u00adtem. Mr. Zdrallek thought imme\u00addi\u00adate\u00adly of RNG, with which he had already com\u00adplet\u00aded numer\u00adous projects. Linossier and Funk didn\u2018t have to think about it for long: \u201eThe approach seemed very promis\u00ading to us, so we imme\u00addi\u00adate\u00adly agreed to col\u00adlab\u00ado\u00adrate in a pilot study,\u201c says Mr. Linossier. What made this approach spe\u00adcial is that the sys\u00adtem (see box below) regards the trans\u00adformer from two per\u00adspec\u00adtives. On the one hand, there is the long-term view which focus\u00ades on longevi\u00adty and is thus impor\u00adtant for invest\u00adment deci\u00adsions. And on the oth\u00ader hand, there is the short-term view which is tar\u00adget\u00aded at the risk of fail\u00adure, and influ\u00adences deci\u00adsion-mak\u00ading relat\u00ading to main\u00adte\u00adnance.<\/p>\n All the main com\u00adpo\u00adnents of the trans\u00adform\u00aders are exam\u00adined care\u00adful\u00adly, from the on-load tap-chang\u00ader and motor-dri\u00adve unit to the cool\u00ading fans. A total of 200 para\u00adme\u00adters ulti\u00admate\u00adly influ\u00adence the out\u00adcome of the assess\u00adment, includ\u00ading main\u00adte\u00adnance his\u00adto\u00adry data and results from on-site mea\u00adsure\u00adments. The col\u00adlect\u00aded data is then ana\u00adlyzed using a spe\u00adcial algo\u00adrithm. \u201eThere are many indi\u00adca\u00adtors we can use to ascer\u00adtain the con\u00addi\u00adtion of the trans\u00adformer. If, for instance, the ther\u00admo\u00adgraph\u00adic mea\u00adsure\u00adment shows that a par\u00adtic\u00adu\u00adlar area of the trans\u00adformer is hot, it is pos\u00adsi\u00adble to local\u00adize the fault. Then detailed mea\u00adsure\u00adment meth\u00adods are required,\u201c explains Mr. Zdrallek. Anoth\u00ader cru\u00adcial ele\u00adment for the assess\u00adment is the oil analy\u00adsis, which can be car\u00adried out by MR in the lab\u00ado\u00adra\u00adto\u00adry of its sub\u00adsidiary Messko. As Mr. Babiz\u00adki makes clear, \u201eit\u2018s a bit like doing someone\u2018s blood-work at the lab, where an increased white blood cell count might indi\u00adcate an infec\u00adtion, for exam\u00adple. Sim\u00adi\u00adlar\u00adly, for trans\u00adformer oil, a high\u00ader acetyl val\u00adue is an indi\u00adca\u00adtion of elec\u00adtri\u00adcal arc\u00ading, which may be a sign that the trans\u00adformer is in poor con\u00addi\u00adtion.\u201c<\/p>\n RNG pro\u00advid\u00aded nine trans\u00adform\u00aders for the pilot study. \u201eOur choice of trans\u00adform\u00aders reflect\u00aded a rep\u00adre\u00adsen\u00adta\u00adtive sam\u00adple of our fleet,\u201c explains Mr. Linossier. After exten\u00adsive tests and sub\u00adse\u00adquent analy\u00adsis, the results were in: All trans\u00adform\u00aders were found to be in good con\u00addi\u00adtion. For some units, the risk of fail\u00adure could even be reduced with sim\u00adple mea\u00adsures, thus extend\u00ading their ser\u00advice life. \u201eThat\u2018s the advan\u00adtage of the method we have devel\u00adoped. Not only do we offer our cus\u00adtomers a con\u00addi\u00adtion assess\u00adment, but also rec\u00adom\u00admen\u00adda\u00adtions for cor\u00adrec\u00adtive action,\u201c empha\u00adsizes Mr. Babiz\u00adki.<\/p>\n The part\u00adners also take spe\u00adcial cas\u00ades into con\u00adsid\u00ader\u00ada\u00adtion. For exam\u00adple, in one trans\u00adformer a high acetyl val\u00adue sug\u00adgest\u00aded there was a prob\u00adlem. As Mr. Linossier stress\u00ades, \u201eMR point\u00aded out that this val\u00adue can vary depend\u00ading on mod\u00adel.\u201c The lim\u00adit-val\u00adue being exceed\u00aded in the trans\u00adformer oil was there\u00adfore triv\u00adial, which made renew\u00adal unnec\u00ades\u00adsary. \u201eWe designed the algo\u00adrithm to take into account the type of tap chang\u00ader used,\u201c adds Mr. Babiz\u00adki.<\/p>\n Mr. Zdrallek is also hap\u00adpy with the new method: \u201eIt is excit\u00ading to me from a sci\u00aden\u00adtif\u00adic point of view. If many net\u00adwork oper\u00ada\u00adtors start work\u00ading with it, then we might be able to use the mass of col\u00adlect\u00aded data one day to find out whether the bath\u00adtub curve is actu\u00adal\u00adly real.\u201c In any case, RNG has decid\u00aded to use this method to exam\u00adine the major\u00adi\u00adty of its fleet of trans\u00adform\u00aders. \u201eWe now have an instru\u00adment for objec\u00adtive\u00adly eval\u00adu\u00adat\u00ading the con\u00addi\u00adtion of our fleet. This is an enor\u00admous\u00adly im por\u00adtant devel\u00adop\u00adment for our strate\u00adgic deci\u00adsion-mak\u00ading,\u201c under\u00adscores Mr. Linossier.<\/p>\n![](\"https:\/\/onload.reinhausen.com\/en\/wp-content\/uploads\/sites\/26\/2017\/11\/Linossier-Babizki.jpg\")
\nAlex\u00adei Babiz\u00adki<\/cite><\/p><\/blockquote>\nCOLLABORATION ON THE TRAM<\/h2>\n
KEEPING THE FLEET IN VIEW \u2013 HOW IT WORKS:<\/h5>\n
![](\"https:\/\/onload.reinhausen.com\/de\/wp-content\/uploads\/sites\/25\/2017\/11\/Flottenmanagement-Waermesensor-300x260.jpg\")
<\/p>\n![](\"https:\/\/onload.reinhausen.com\/en\/wp-content\/uploads\/sites\/26\/2017\/12\/Fleetmanagement_Index.jpg\")
<\/p>\n<\/div>\n<\/div>\nLONGEVITY AND FAILURE RISK IN FOCUS<\/h2>\n
![](\"https:\/\/onload.reinhausen.com\/en\/wp-content\/uploads\/sites\/26\/2017\/11\/Zdrallek2-300x200.jpg\")
AN INSTRUMENT FOR OBJECTIVE FLEET EVALUATION<\/h2>\n
<\/i> Learn more about this collaboration in an interview with Jan Patrick Linossier and Markus Zdrallek.<\/a><\/h5>\n
\nYOUR CONTACT<\/h2>\n