Panbo

TDI inverters & converters, modular & hot swappable

... written for Panbo by Ben Ellison and posted on Aug 17, 2007

Electra TDI inverters cPanbo

This week I spent some more time aboard the fabulous Electra, back at Lyman Morse after a month long trial/pleasure cruise to New York. I’ve come to realize that her owner, George Wallner, has a deep understanding of electricity that’s similar to the way some fine chefs I’ve met know the science and mechanics of their basic materials like, say, butter. Wallner is not only a talented electrical engineer but also a guy who’s run a company that manufactured mission critical electronics—credit card swiping systems—and a yachtsman who’s been seriously cruising a boat similar to Electra for ten years. Don't you want to see how he’s equipped his new ride?

How about those three TDI LCE series 1.0kVA 24v DC to 120 v AC inverters upper left. They run in parallel (with another bank of three not in the photo) and can be hot swapped as demonstrated…undoing a thumb screw and pulling the handle takes a unit offline until you slide another back in and lock its handle up. That’s it, though it shouldn’t happen often as TDI claims “over 9,000 units fielded with a demonstrated MTBF of > 900,000 hours/module.” Wallner notes that Mean Time Between Failure can be a tricky measure, but certainly favors industrial equipment like these units, which he says are commonly used in cell phone towers.
   Even more unusual are the five TDI Mercury 1200 watt DC-to-DC converters to the right (three more coming), which Wallner uses simply to regulate the output of Electra’s 24v battery bank. He retrofitted similar converters on the previous boat and says that changing from voltage that varied almost 20% to a stable supply had all sorts of benefits. His halogens bulbs and DC motors lasted much longer, and his battery charging system no longer got confused about the state of the batteries it was minding. By the way, both these devices use switched-mode power supplies, as opposed to traditional and very heavy linear transformers. When I studied isolation transformers last winter, I was told that the old way is probably more reliable but Wallner only grinned when I suggested this. Reliability in general, he says, comes from either high volumn or high cost manufacturing, either of which is problematical for marine only operations. Handling electricity around a boat, especially a big boat, is tricky business, and I’ll share some more Wallner wisdom soon.

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