“It Was Pretty Tough”

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Why do you need a mobile transformer?

After hur­ri­cane Sandy in 2012, we real­ized that the longest our cus­tomers will accept being out of pow­er is three to five days and after that cus­tomers, includ­ing you and me, can’t tol­er­ate liv­ing life with­out elec­tric­i­ty. So typ­i­cal trans­former down­time at Con Edi­son, from the time it trips to the time it gets restored is about 14 days. These are three-phase units that require a lot of assem­bly, pro­cess­ing of oil, wiring etc. and actu­al­ly also the phys­i­cal move­ment of these units.

Hav­ing gone through Sandy as one of the oper­a­tional and plan­ning chiefs dur­ing the recov­ery effort, I real­ized we have to do bet­ter and in addi­tion after 9/11 and look­ing at cur­rent world affairs – the geopo­lit­i­cal scene – there are a lot of threats: phys­i­cal threats, and also actu­al actions that have tak­en place. So you say to your­self: ok, if some­body comes and destroys our trans­form­ers, the quick­est we can do replace­ment if we have spares on hand is 14 days – which is three times our cus­tomers’ expec­ta­tions. And resilien­cy must be not just to ter­ror­ism but also to nation­al weath­er, earth­quakes, flooding—all those sit­u­a­tions.

What is the technical concept?

I said to the trans­former man­u­fac­tur­er: “Here is my con­cept: I want a trans­former that’s dual volt­age 345 to 138 or 138 to 69. I want it with a full tap-chang­er, plus or minus twelve per­cent. I want 170 per­cent over­load capa­bil­i­ty which is kind of unique to us and I will make it easy for you. Put the tap chang­er inside the main tank – which was a ConEd first since it had nev­er been done before – and I want a man­u­al volt­age selec­tor between 345 and 138 kV. In addi­tion to that, I want plug-in bush­ings on the high side and the same on the low side. In addi­tion, I also want flex­i­ble HV cables that con­nect to the low-side, two-part bush­ing adapter. Most impor­tant­ly, I want min­i­mum assem­bly required on site when moved, so I want it be moved oil filled. Fur­ther­more, all of this should not weigh more than 100 tons oil filled and it should fit in the car­go bay of a Lock­heed C5A Galaxy or an Antonov AN 124 car­go air­craft. This was a pret­ty tough chal­lenge as it had nev­er been done before and goes against most tra­di­tion­al trans­former design approach­es.

How did you approach this task?

We took the best of our tra­di­tion­al trans­former and tap-chang­er designs and said ‘ok we have a design and because the trans­porta­tion is a big issue with these trans­form­ers let’s make it sin­gle phase’. By hav­ing sin­gle phase you can quick­ly trans­port it. Also, by hav­ing cable con­nec­tions on the sec­ondary side, you just need one fix point on the high side to line it up to your exist­ing bus and you don’t need to line it up per­fect­ly to do that.

The oth­er thing that I also men­tioned is that ter­ror­ism and extreme weath­er events are very rare – we call them high impact, low fre­quen­cy – so you can­not real­ly jus­ti­fy hav­ing a unit sit­ting there just for those occa­sions. So I said ‘what I also want is for this to be used on a day-to-day basis so that in the mid­dle of sum­mer, if we have a three-phase unit fail­ure, I can bring this in and con­nect it quick­ly.’

“When we say ‘go’, the trans­former must be up and car­ry­ing load in less than 72 hours.”
San­jay Bose

When the OEM asked of my expec­ta­tion for ener­giz­ing, I said ‘3 to 5 days – but more like 3. And it’ll be used on reg­u­lar basis, so that peo­ple don’t for­get how to use it and all the parts have to be con­tainer­ized – the cables, the plug-and-play type equip­ment and the relay pro­tec­tion sys­tems, etc.’ And the oth­er thing I said is that because it will be placed on streets or inside sub­sta­tions, we won’t have full envi­ron­men­tal con­tain­ment so I want an envi­ron­men­tal­ly friend­ly flu­id that has a high­er igni­tion tem­per­a­ture, because we won’t have reg­u­lar fire pro­tec­tion on it. At the end of the two years of R&D the fol­low­ing dia­logue came up: ‘You want a tap-chang­er’; ‘yes’; ‘you know that takes a long time’; ‘yes’; ‘well, we are talk­ing to Rein­hausen’.

So then we took it a step fur­ther. We took it to my con­nec­tions work­ing with the gov­ern­ment. We actu­al­ly took it to the US Air Force load mas­ters to come up with a load­ing plan. I now have a load plan for a C5A Galaxy where this unit will sit in the car­go bay – the con­ser­va­tor and the tank.

My vision is that from the time we say ‘go’ to the time it’s ener­gized and car­ry­ing will be less than 72 hours. And I think that would be phe­nom­e­nal because I don’t know of any oth­er prod­uct at 300 MVA that can be placed in ser­vice in 72 hours and have all these ben­e­fits like a reg­u­lar trans­former with full volt­age reg­u­la­tion. Peo­ple also talk about imped­ance issues. Going through this design you can actu­al­ly add some small series reac­tors to change the imped­ance. Our auto-trans­former imped­ances are 4 to 7 per­cent, and by adding a series reac­tor, it can serve the needs of many util­i­ties at the same time. So that’s tru­ly an equip­ment shar­ing pro­gram. It could be here, it could be in Ger­many, it could be any­where.

Why do you equip all new resiliency units with monitoring systems from Reinhausen?

We want to have a way to ensure that the unit is reli­able at all times. The trans­former is good but the mov­ing parts are impor­tant. You want to make sure that, when you need it in emer­gency, you have a com­plete ready-to-use unit. So hav­ing the mon­i­tor­ing unit actu­al­ly helps you diag­nose and fix things before they become an emer­gency.

What is your experience with those monitoring systems?

Rein­hausen mon­i­tor­ing sys­tems have been very good but the best part is that, over time, Rein­hausen has worked to improve the prod­uct. So, it’s not the same prod­uct as ten years ago. To an aver­age oper­a­tor, the dis­play should actu­al­ly tell you what’s wrong instead of show­ing codes that engi­neer­ing has to deci­pher. The engi­neer­ing lin­go on the dis­plays are clear­ly stat­ed in oper­a­tor lan­guage for any-one to read and under­stand – a real­ly friend­ly inter­face. Also com­put­er pow­er has grown; soft­ware, firmware has grown; plat­forms have grown as well as expe­ri­ence.

Per year on aver­age, it saves us between six to eight pos­si­ble tap-chang­er fail­ures. Oth­er than the resilien­cy units, all our trans­form­ers have the tap chang­er out­side the main body. So if a fail­ure occurs, the bar­ri­er board breaks and the cables get impact­ed and often times we end up replac­ing the trans­former. In addi­tion, if the tap chang­er is faulty the oil in the main body does get affect­ed and one does not have to drain the unit to fix it. So the idea of hav­ing an inter­nal tap chang­er raised a few con­cerns. How­ev­er, with the increased reli­a­bil­i­ty of Rein­hausen tap chang­ers, the prob­a­bil­i­ty of such a fail­ure has been reduced enough for us to take this risk. And I think that’s great because chang­ing a trans­former means many mil­lions of dol­lars as opposed to going and fix­ing the tap chang­er.

Regarding technical consultancy: how important is the technical competence of suppliers like Reinhausen?

Rein­hausen, unlike quite a few man­u­fac­tur­ers, has real­ly tech­ni­cal­ly com­pe­tent staff. Most of my inter­ac­tions with some major com­pa­nies have been more with mar­ket­ing folks. There is a great dis­tinc­tion between mar­ket­ing and tech­ni­cal skills. The peo­ple we some­times inter­face with are mar­ket­ing peo­ple who are not tech­ni­cal­ly strong and this leads to a lot of back and forth to fix designs and real time issues. My expe­ri­ence in going to the Rein­hausen fac­to­ry and meet­ing peo­ple: you see both sides of it. But most impor­tant­ly, what’s strik­ing is that they are very pas­sion­ate about their prod­uct; they take a lot of pride in their prod­uct, which I don’t see often. And so they know their stuff tech­ni­cal­ly and it becomes eas­i­er for them to mar­ket it. For a cus­tomer, that is the best of both worlds and is very sat­is­fy­ing to expe­ri­ence.

Thinking into the future: Which technical requirements will become important for power transformers in megacities like New York?

With the advent of renew­ables and inte­grat­ing them into our sys­tem, there are a lot of issues with har­mon­ics being gen­er­at­ed and then step­ping them up and bring­ing them into the trans­mis­sion side. Volt­age reg­u­la­tion is one, check­ing har­mon­ics is the oth­er. What I envi­sion 5 years, 10 years from now is that our think­ing needs to change. We need small­er, cheap­er, lighter units like the resilien­cy trans­form­ers. So they only last 20 years, but if they are eas­i­er to replace, I’d rather do small­er invest­ments over time than one large invest­ment today which has to be repeat­ed. So I change the trans­former every 20 or 30 years.

I think that’s much bet­ter than hav­ing a very expen­sive unit sit­ting around when I don’t know what my future looks like, because I could end up with a lot of strand­ed costs. I have to be smart enough to know how I can max­i­mize my invest­ment so that I can make sound busi­ness deci­sions with­out sac­ri­fic­ing reli­a­bil­i­ty. Any busi­ness includ­ing yours would do that. In oth­er words, if you need a reli­able car for work, why go buy a top brand twice as expen­sive as anoth­er when you can replace the less expen­sive car more often and still have a reli­able means of trans­port. That’s the busi­ness mod­el we need to aspire to.