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Hidden Energy Hogs—What Dry Transformers are Costing You

transformerPigDoes your organization’s portfolio include buildings larger than 15,000 square feet? If so, you may find some nasty things hiding behind closed doors that are sapping energy and dollars from your bottom line.

The culprits are dry transformers—those ugly, humming electrical distribution units responsible for stepping down the voltage from your primary electrical power supply to the level needed for your 208/120-volt power outlets or 277-volt lighting.

They’re usually found in locked mechanical rooms or “Electrical” closets, where they may have been quietly doing an inefficient job for 10, 20, 30, 40 or even 50 years. Electricity lost during this process is dissipated as heat, which can further exacerbate energy use by increasing cooling demand in air-conditioned facilities.

The Problem

The basic problem is that these older transformers were designed intentionally for maximum efficiency at 35 percent of their maximum load. But most offices, medical facilities, retail operations, hotels, motels, restaurants, classrooms, manufacturing sites, military buildings, dormitories, and even data centers operate at closer to 5 to 15 percent of maximum load. If you’re running your electrical distribution system with some of these little beasties, it’s a little like buying a Ferrari, but never driving it faster than 10 miles an hour.

The construction of some of these older transformer units can also contribute to operational inefficiencies. Steel makes up the core of the transformer, and the cheaper the steel, the less efficiently the transformer generally operates.

The Solution

The good news is that low-cost, efficient replacement transformers are available with specifications more attuned to the loads actually present in your buildings.

The U.S. Department of Energy (DOE) estimates if older dry transformers were replaced with energy-saving transformers, the energy saved annually might be more than 60-80 billion kilowatt-hours, at a cost savings of $6 billion or more—that’s enough electricity to run the country for several days.

So how much could YOU save? Here’s some information to help you find out.

First, determine how many transformers you have in your building or building portfolio. Let’s use schools as an example. The average elementary school has three to five transformers, a middle school has 7 to 15, and most high schools have 12 to 25, depending on the size and floor plan of the school.

Second, do the math. A typical 75 KVA transformer uses around 880 watts per hour to energize the coil. An energy-efficient transformer will reduce power to energize its coil down to 180 watts, saving 700 watts per hour. This means that one energy-saving transformer in a school could save over 300,000 kWh in 50 years.

That’s a lot of electricity, and a lot of money—perhaps $30,000 over the life of the unit, depending on prevailing electric rates. Considering the typical price of an energy-efficient replacement unit ($1,000-3,000), your organization could realize significant savings in a relatively short time.

Transformers in Your Future

The U.S. Department of Energy has promulgated a new standard (CSL-3) for energy efficient transformers which will have an efficiency of 98.6% with energy losses 30 percent less than the current standard (known at TP-1). And TP-1 is probably a big improvement over many dry transformers currently operating in your buildings.

Why not do the research and see how much you could save in your facilities?

Acknowledgement: My thanks to Larry Schoff for providing technical background information for this blog article.