208V to 220V Buck-Boost Transformer — Step-up, Single Phase
See how a 208V to 220V single phase buck-boost transformer corrects voltage and how to select the proper model.
Choosing a 208V to 220V transformer
208 volts is the phase-to-phase voltage of a 208Y/120 wye service, not a low version of 240. It is its own nominal system, and equipment nameplated 220V is its own population of machines, most of it built to European or Asian specification rather than North American practice. A 208V to 220V buck-boost transformer closes the 12 volt gap between them, raising the supply about 5.8 percent so an imported machine, a 220V motor or a 220V control transformer sees the voltage its designer assumed. It is the smallest correction made from a 208V service, and because the transformer processes only the difference between input and output, a modest unit supports a substantial machine. Available single-phase and three-phase in 10 through 60 amp ratings.
A 220V nameplate in a US building usually says something about where the equipment was built. IEC 60038 harmonized European supply at 230V, but a great deal of hardware still ships marked 220V or 220-240V, and 220V remains a working standard across much of Asia and Latin America. Most US commercial and light industrial tenant space, meanwhile, is fed 208Y/120.Machine tools and fabrication equipment: imported CNC mills and lathes, laser cutters and engravers, plasma tables, press brakes and saws.Small-shop production machinery: packaging and filling lines, label applicators, printing and bindery equipment, embroidery and textile machines, woodworking routers.Food service and hospitality equipment of European origin: espresso machines, combi ovens, dough sheeters, blast chillers and commercial laundry equipment.Laboratory, dental and clinical equipment: autoclaves and sterilizers, centrifuges, environmental chambers, vacuum pumps and compressors.Smaller motor loads generally, including 220V fans, pumps, hoists, conveyors and gate operators, along with the drives and control transformers that shipped with them.The complaint is consistent. The machine runs, but it stalls on heavy cuts, the drive reports undervoltage on acceleration, the control transformer runs hot, or a contactor chatters at the end of a long branch circuit. None of it reads as a supply problem until someone meters the terminals while the machine is working.