Overview of Transformers

Tue, Mar 24, 2009

Building Basics

Ever walk by a strange closet in your office building, and hear a humming sound? Thought maybe there is a monster in the closet? Most likely the closet contained a transformer.

Transformers are the beasts that make sure that the electricity that gets to the outlet is of proper strength. Assume that lots of power comes into a building from the street, and transformers ‘transform’ the electricity into usable quantities.

When a transformer gets old, they break down and begin to whistle. You have most likely heard the transformer rattle at an old office building. My experience is that transformers don’t get replaced until they go bad, and finding a 20-30 year old transformer is not unusual. Transformers in a building can start at $5,000 per, and go up and over $100K, depending on the use.

Some transformers are more energy efficient than others. How do you figure out what the best purchase is? Too often companies compare purchase price, rather than looking at lifecycle costs. Looking at lifecycle costs accounts for the cost of ownership. This is the calculation that drives people to buy CFL bulbs. A CFL bulb costs more than a regular bulb, but the higher cost comes with the benefits of a much lower energy bill. So while a CFL costs more, to decide whether to purchase one, you need to account for what it saves.

Transformers are the same way. Just as with light bulbs, the better transformers save money for building ownership over time. Perhaps because they cost so much, my experience is that companies tend to ignore cost of ownership issues when purchasing transformers.

My experience is that transformers that are non-linear – rated for modern use – are the most efficient. Early transformers were designed for the steady loads that existed before computers and other office electronics. ‘Modern’ transformers are built to handle these loads.

The challenge is that it is very hard to compare cost / benefit on different transformers. You need a very knowledgeable vendor – one who understand lifecycle pricing, and ideally, one who sells both types.

Just drawing on my limited experience, I have seen numbers where energy efficient transformers will payback their extra cost within 3-5 years, and maybe sooner. There are a bunch of variables, but the biggest variable is how much of a rebate can you get from the government. Considering how long these things tend to stick around, it is likely that the money you spend to get energy efficiency will be money well spent. The purchase could also help you earn some LEED points.

If you have a long-term relationship with your building as either an owner or a tenant, don’t forget the buzzing monster in the closet. Ignore it at your own expense.

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