“PSTs replace redispatch and pay for themselves in a short time.”

With­out Jür­gen Kollmannsberger’s design of the on-load tap-chang­ers, no phase shifter goes online.

In order for phase-shifting transformers (PST) to be put into operation, experts like Jürgen Kollmannsberger carry out designs of the installed on-load tap-changers beforehand. The electrical engineer has been supporting MR Sales for many years and develops tap-changer designs for HVDC transformers, furnace transformers, shunt reactors and also phase shifters — of which there are now over 140! Here he explains what is important in this regard.

When you design tap changers for phase-shifting transformers like the ones in Würgau, what is important?

I have to rec­on­cile impor­tant key val­ues such as the requir­ed over­load, the short-cir­cuit imped­ance of the trans­former, the insu­lat­ing medi­um and the pow­er fac­tor cosphi with defined per­for­mance data of the tap chang­er such as the max­i­mum per­mis­si­ble switch­ing capac­i­ty, the pre­s­e­lec­tor switch­ing capac­i­ty and the insu­lat­ing capac­i­ty of the selec­tor. This plays a major role in safe, reli­able sys­tem oper­a­tion. It may well take two to five runs before an order is placed.

How long does it take from a PST order to commissioning?

One to two years. How­ev­er, MR is involved even before that, dur­ing the prepa­ra­tion of the offer. Since sev­er­al trans­former man­u­fac­tur­ers usu­al­ly bid on a sin­gle project, we some­times have to car­ry out four to five designs at the same time. This is very time-con­sum­ing and requires a lot of clar­i­fi­ca­tion.

Will the investment in a phase shifter pay for itself?

Yes, usu­al­ly after six months to a year. PSTs reg­u­late the increased feed-in of green pow­er, which affects load flows in the grid. In this way, they replace expen­sive redis­patch mea­sures. Phase shifters are also used in Euro­pean pow­er trad­ing when ener­gy is pur­chased when prices are low and sold when prices are high. The pay­back peri­od here is very short.

Many interpretations, much experience — do you remember any personal highlights?

There are always those. For exam­ple, a cus­tomer recent­ly called me from the air­port on Fri­day after­noon and asked for tech­ni­cal sup­port. It had to be done quick­ly so I pre­pared the pre­sen­ta­tion with my cal­cu­la­tion results by Sat­ur­day noon. The cus­tomer was very pleased with the uncom­pli­cat­ed and fast sup­port and in the end he won the order. Of course, some­thing like that stays in one’s mem­o­ry.

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