EnergyLines June 2016

Backup transformer joins primary substation to ensure continued grid reliability for members


Hoosier Energy is installing a backup transformer for the Bloomington substation, but just taking delivery of this essential piece of equipment for grid reliability was no simple task.


The backup transformer joins a duo of in-service transformers, one of which was installed two years ago after one of the pair failed. The transformer will serve as a backup to the in-service units to improve grid reliability in the event of an unforeseen interruption to power delivery.


A great deal of coordination and planning went into moving the giant beast from the supplier’s facility in Waukesha, Wisconsin to its new home in Bloomington.


After a 430-mile trek over rail from Wisconsin to Martinsville, the transformer was loaded onto a special road trailer to make the final journey to Bloomington. Hoosier Energy worked with contractors, the city of Martinsville’s mayor’s office, Indiana State Police, the Indiana Department of Transportation and I-69 Partners to move the giant gray hulk from the Martinsville rail siding to the G&T’s Bloomington substation.


Unlike the move of a station transformer two years ago, the final leg of this transformer’s journey down S.R. 37 took place in a construction zone for I-69 Section 5. Despite a slight delay while final inspections took place, some tight turns, negotiation of overhead line clearances and traffic snarls, the transformer move was completed successfully, taking a little over three hours to lumber down S.R. 37 at 10 m.p.h. escorted by the Indiana State Police.


“Two years ago, the station’s new transformer took the same journey,” said Brady Mann, Hoosier Energy’s Manager of Delivery Services. “We were a little worried this time about going through the construction zone, but in the end the months of careful planning paid off.”


The first phase of the move was completed on May 19, causing some traffic delays on southbound S.R. 37.  After being transferred to a smaller trailer capable of using a narrower service road, it was hauled into the substation the next day.


Set in place on a concrete pad, the work now includes installation of large radiators, an oil conservator tank, bushings and vacuum filling with oil. The transformer will remain de-energized as a spare for the two existing units currently
in service.


RARE SIGHT: People headed out of local businesses in Martinsville to take photos of the 200-ton transformer move.

10 things you should know about transformers

  1. Transformers are used in all power delivery applications, both large and small.
  2. They boost electricity voltage for efficient long distance travel while reducing voltages for delivery to consumers.
  3. This variation in voltage control is called “stepping up” or “stepping down” voltage and is critical to electrical reliability.
  4. The transformer shown above is a 345-kilovolt to 230-kilovolt step down transformer. It is essential for reliable power delivery in the bulk electric system in central Indiana.
  5. Age is a factor. The average Hoosier Energy transformer is 28 years old, which is less than the industry average of 35 to 40 years.
  6. Failure of a large transformer can result in loss of load during peak conditions and impact generation levels due to transmission system congestion.
  7. Test results and historical data help determine the health of transformers. Power flow studies determine the consequences of a transformer outage. This information enables personnel to determine which type and how many spares are needed.
  8. Once filled with oil and all assembled parts, a completed, large transmission transformer weighs 652,000 pounds or about 327 tons.
  9. Hoosier Energy owns 29 transmission transformers and 12 generation transformers.
  10. The spare transformer weighs 406,700 pounds; is 16 feet, 10 inches high; 13 feet, 3 inches wide and 28 feet, 5 inches long.


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