Project completed in record time

    Special Minnesota Power project successfully completed right on schedule – and just in time for Christmas

    At the Field Acceptance Test (FAT) in Duluth: Tim Young, Derek Johnson (beide RM) and Eugen Nagel (MR, from left top right.).
    At the Field Acceptance Test (FAT) in Duluth: Tim Young, Derek Johnson (beide RM) and Eugen Nagel (MR, from left top right.).

    Shortly before the end of the year, MR was responsible for the successful completion of a special project with an urgent deadline in the American state of Minnesota.

    Hugging the Canadian border in Minnesota, the city of International Falls is home to a substation that operates two transformers in series. These are phase shifter transformers, and are crucial pieces of equipment that are responsible for ensuring power is exchanged between Minnesota and Ontario, Canada, along a 150 MVA line.

    The transformers were previously controlled by electronics products provided by a third-party manufacturer, but Minnesota Power then charged MR with the task of fully replacing this outdated equipment with a combined TAPCON® system – and requested a deadline of mid-December 2014. The challenge was set: Within approximately 4 weeks, software that was designed specifically for the TAPCON® system had to be developed and tested with the aim of meeting all the customer's functional requirements. Thanks to the tireless dedication – as well as willingness to work over the weekends – and the spirit of partnership demonstrated by several MR colleagues, the FAT (Factory Acceptance Test) went ahead as scheduled at the customer's premises in Duluth between 16 and 22 November 2014. The all-important final deadline for commissioning at the International Falls site – 6-13 December 2014 – was met too. At the site, Tim Young and Derek Johnson from Reinhausen Manufacturing (RM) were on hand to provide Eugen Nagel (MR) with support. The colleagues installed a system comprising four TAPCON®260 devices in the substation, before successfully testing the entire facility together with the customer.

    At the same time as this work was going on, two service specialists of MR adapted the electromechanical locking mechanisms on the motor-drive units of the two phase shifters to the new conditions and performed a range of function tests. With temperatures in this northern region of the world capable of plummeting to -20°C, the only way for the conversion work to be carried out on the TAPMOTION® EDs at all was to enclose the drives in temporary tents and heat them with gas burners. To stop the oil temperature from dropping below the minimum tap-changer point, it was even necessary to connect the transformers to the power grid each night and leave them running without load so that the no-load losses (around 18 kW per transformer) could keep the transformer oil sufficiently warm.

    To Minnesota Power's complete satisfaction, handover took place right on schedule in the middle of December 2014. With a whole two months of successful operation now behind it, the installation has been able to provide some key insights into operating circumstances. And Minnesota Power already has follow-up orders in the pipeline.