Coal Age

JUN 2018

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June 2018 www.coalage.com 39 operating ideas continued Retrofit Explained Retrofit transformers represent a large cost savings for plant managers seeking to reduce capital expenses primarily because of the plug-and-play advantage of a per- fect fit. Yet, without proper manufactur- ing controls, performance and reliability could end up sacrificed. When it comes to the material used in the windings of a well-manufactured retrofit, copper is a superior conductor to aluminum because copper offers less re- sistance, hence less heat. Even the geom- etry of the windings makes a difference, with round-wound holding the advantage. Attention to detail also pays dividends in the retrofit manufacturing process. Hand-wiring yields the highest quality. The deburring of the copper conductor also helps ensure that the insulation won't be punctured and create a short circuit. Even insulation plays a major part in ensuring reliability. As temperatures can reach 200°C in a dry transformer on a daily basis, skimping on insulation can lead to disastrous consequences. Glastic fiber- glass insulation or Nomex provide signifi- cantly greater protection from fires and short circuits than paper insulation. "Ameren wanted top quality," said Alan Ober, vice president of engineering and manufacturing for ELSCO Trans- formers. "The dry-type unit we made for them incorporated all the characteristics of a well manufactured retrofit so that we could give them a three-year warranty where one year is more common." Fast, Smooth Upgrade at Rush Island According to a Department of Energy (DOE) June 2012 study entitled Large Pow- er Transformers and the U.S. Electric Grid, "In 2010, the average lead time between a customer's large power transformer order and the date of delivery ranged from five to 12 months for domestic producers." Too long. Aside from having to meet the stage gates for any project, the window for an outage must compete with other projects. Miss it, and rescheduling can de- lay implementation for weeks and quickly inflate costs as contractors sit idle. For the Rush Island transformer up- grade, the window was Columbus Day weekend 2017. Retrofitting allowed them to complete the job within the approved timeframe. "We already had received the draw- ings, so it was easy on our part to build the transformers to spec and get them shipped out quickly," explained Ober. "An electrical contractor did the work and had no installation issues whatsoev- er," added Fischer. "ELSCO placed the bus bars where they needed to be and provid- ed cabling of sufficient length to reach the existing terminations. It fit like a glove." After implementation, Rush Island ordered two more units that also had to be delivered on a short timeline, this time with different voltages. To date, the utility reports it has had no issues with any of the transformers and that everything is func- tioning to specifications. For more information, contact ELSCO at www.electricservice.com.

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