Who inven­ted it?

With the com­bi­ned pro­tec­tion and field con­trol device KOMBISAVE, the deve­lo­pers of the Swiss Phoe­nix Con­tact sub­si­dia­ry NSE have hit the bull’s eye. Even though this should be avoi­ded if at all pos­si­ble when it comes to the power grids and their safe­ty.

Just fol­low the 110 kV line to the end, the­re are no num­bers the­re.” It was clear from the direc­tions that a visit to the sub­sta­ti­on in Kem­pen on the Lower Rhi­ne would be a spe­cial one. In other words, look up, with the high vol­ta­ge line firm­ly in view, and slow­ly fol­low it down the road.

Kem­pen is a city of 36,000 peop­le on the Lower Rhi­ne. It is beau­ti­ful­ly situa­ted, has a past rich in tra­di­ti­on, and is cur­r­ent­ly pro­spe­ring. Rein­hard Bretz­ke and Micha­el Kai­ries are wai­ting for us in the indus­tri­al park on Indus­trie­ring Ost. The two are employees of the local public uti­li­ty com­pa­ny that is respon­si­ble for the ener­gy sup­ply to their home town. And first of all, they take us right to the heart of their work – their net­work con­trol cen­ter.

Hous­ton – we have lan­ded

The wall of moni­tors is a bit remi­nis­cent of the famous NASA con­trol room for the astro­nauts at Cape Ken­ne­dy. But things are all very earth­ly here. “We are respon­si­ble for our city’s ener­gy sup­ply,” Rein­hard Bretz­ke says sim­ply. It sounds qui­te down to earth at first, but it is a job with a direct con­nec­tion to the future. “We are cur­r­ent­ly con­ver­ting our net­works ent­i­re­ly to a cen­tra­li­zed ope­ra­ti­on with digi­tal power dis­tri­bu­ti­on con­trol sys­tems.” So a litt­le NASA after all!

Michael Kairies in the network control room

The power grids are part of what is refer­red to as the cri­ti­cal infra­st­ruc­tu­re; i.e., they are sub­ject to par­ti­cu­lar­ly strict stan­dards and demands for safe­ty and relia­bi­li­ty. No won­der, becau­se wit­hout elec­tri­ci­ty, not even the water sup­ply can run in modern civi­li­za­ti­on. Bretz­ke is an old hand at ener­gy. For a good 45 years, he’s been faith­ful to the topic, and for a long time was respon­si­ble for the ener­gy sup­ply in Hil­des­heim in Lower Sax­o­ny. He has been respon­si­ble for the power sup­ply in Kem­pen for five years.

I was attrac­ted to the green mea­dow for the net­work moni­to­ring divi­si­on in the most beau­ti­ful city on the Lower Rhi­ne. Tog­e­ther with my twel­ve employees, I look after the medi­um- and low-vol­ta­ge grid and the asso­cia­ted com­mu­ni­ca­ti­ons tech­no­lo­gy for grid moni­to­ring. The tasks are real­ly varied, so the ran­ge of demands is extre­me.”

Rein­hard Bretz­ke (l.) and Phoe­nix Con­tact expert Timo Beuth

One per­son who takes it in stri­de is Micha­el Kai­ries. The 38-year-old ener­gy elec­tro­nics tech­ni­ci­an is respon­si­ble for the net­work con­trol cen­ter, among other things. He’s the­re­fo­re an expert when it comes to inte­gra­ting pro­tec­tion and auto­ma­ti­on sys­tems into the Kem­pen sys­tem. With nim­ble fin­gers, he calls up the appro­pria­te dis­play on one of the moni­tors and shows us the dis­tri­bu­ti­on of the local Lower Rhi­ne power grid and both the fee­ders and the major custo­mers who are buy­ing. Mean­while, Rein­hard Bretz­ke exp­lains why we are actual­ly here.

We need smart power grids in the future.”

Rein­hard Bretz­ke, Head of Ener­gy Sup­ply, Stadt­wer­ke Kem­pen

Our power grids are facing ever-gro­wing chal­len­ges. The con­ver­si­on of the ener­gy sup­ply to rene­wa­ble ener­gies is chan­ging the feed-in com­ple­te­ly. For deca­des, we have worked with con­stant feed-ins from lar­ge power plants. Now, new ener­gy sources are con­stant­ly being added that are also fed in uneven­ly and dis­tri­bu­t­ed in a decen­tra­li­zed man­ner. At the same time, howe­ver, we still need a high level of sup­ply secu­ri­ty on the custo­mer side. This means that we also have to rethink power dis­tri­bu­ti­on. We need smart grids in the future.”

When raw cur­r­ents flow hazard-free

Timo Beuth, Field App­li­ca­ti­on Engi­neer at Phoe­nix Con­tact, exp­lains: “In ener­gy tech­no­lo­gy, in addi­ti­on to high sup­ply relia­bi­li­ty, no per­so­nal inju­ry or sys­tem dama­ge should occur in the event of a fault.” Ground faults occur most fre­quent­ly in the power grid. In the pri­va­te sec­tor, for examp­le, this could be a defec­tive cable insu­la­ti­on on the iron; in the medi­um-vol­ta­ge dis­tri­bu­ti­on net­work, it could be an exca­va­tor that damages the cable insu­la­ti­on or a branch that tou­ches the over­head line during strong winds.

In the examp­le of the iron, a ground fault cur­rent flows out over the human body and over the ground when tou­ch­ing the defec­tive line point. A resi­du­al cur­rent device (RCD) detec­ts that a resi­du­al cur­rent is flo­wing and swit­ches off imme­dia­te­ly. So quick­ly that you won’t even noti­ce the elec­tri­ci­ty. The elec­tri­cal sup­ply can be quick­ly res­to­red by swit­ching on the RCD, the per­son sur­vi­ves, and the elec­tri­cal sys­tem has been pro­tec­ted.

If a branch tou­ches a medi­um-vol­ta­ge over­head line due to a gust of wind, things will look a bit dif­fe­rent. The ener­gy pro­vi­der doesn’t want to imme­dia­te­ly switch off the power to an ent­i­re sup­ply area, but it also doesn’t want to end­an­ger peop­le and sys­tems due to an earth fault cur­rent. Becau­se the forces at play here are much grea­ter. Even get­ting clo­se to the source of the error can lead to a dest­ruc­tive elec­tric arc. So the fault cur­rent is vir­tual­ly bypas­sed at the “fuse.” Using the “KOMBISAVE” pro­tec­tion and field con­trol device from Phoe­nix Con­tact sub­si­dia­ry NSE, the trick is to be able to safe­ly loca­te the ground fault cur­rent and only switch off the power grid local­ly. The low-resis­tan­ce neu­tral eart­hing of the medi­um-vol­ta­ge trans­for­mer redu­ces dan­ge­rous sin­gle-pole earth short-cir­cuit cur­r­ents and pre­vents an imper­mis­si­ble vol­ta­ge increa­se in the imme­dia­te vicini­ty of the fault loca­ti­on. By swit­ching over to other exis­ting reser­ve feed-ins, secu­ri­ty of sup­ply can be quick­ly res­to­red wit­hin a few minu­tes thanks to the digi­tal power dis­tri­bu­ti­on con­trol sys­tems.

Keep your hands in your pockets

Rein­hard Bretz­ke opens the doors in the sub­sta­ti­on, whe­re the 110 kV vol­ta­ge from the trans­port net­work is trans­for­med and dis­tri­bu­t­ed to the 10 kV medi­um vol­ta­ge of the dis­tri­bu­ti­on net­work. “Bet­ter keep your hands in your pockets,” he says, warning against over­ly explo­ra­to­ry came­ra angles with fatal con­se­quen­ces. In this case, negli­gence is a dan­ger to life.

Behind a con­trol cabi­net door with the inscrip­ti­on “Stern­punkt­bild­ner” (neu­tral point-for­mer), the NSE KOMBISAVE is alrea­dy ligh­t­ing up for us. “We were real­ly able to adjust and ope­ra­te the pro­tec­tive device almost imme­dia­te­ly, and are still enthu­si­astic about the easy instal­la­ti­on. The inte­gra­ti­on into our auto­ma­ti­on sys­tem was pro­blem-free, and the requi­red para­me­ters were quick­ly set in the pro­tec­tive device. In the end, it took us less than an hour to have a rea­dy-to-use and para­me­te­ri­zed pro­tec­tive device for a spe­cial app­li­ca­ti­on out of the box – and that wit­hout rea­ding us in. The experts from Phoe­nix Con­tact were the­re to help us with one or two details in no time,” says Micha­el Kai­ries, visi­b­ly satis­fied with the team­work. “And the Digi­com para­me­te­ri­za­ti­on soft­ware of the NSE devices is not only free of char­ge, but also intui­ti­ve to use.”

This not only saves Kem­pen public uti­li­ties time and effort in renewing its power grids. They are also inves­ting in the sup­ply secu­ri­ty of their busi­nes­ses and citi­zens in the “most beau­ti­ful city on the Lower Rhi­ne.”

Stadt­wer­ke Kem­pen

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