480V to 440V Buck-Boost Transformer — Step-down, 3-Phase Delta
See how a 480V to 440V 3-phase delta buck-boost transformer corrects voltage and how to select the proper model.
Choosing a 480V to 440V transformer
A 480V to 440V buck-boost transformer drops a standard US 480 volt supply by about 8 percent so equipment nameplated 440 volts receives the voltage it was designed around. The mismatch shows up constantly. 480 volts is the ordinary industrial service in the United States, while 440 volts is what is stamped on shipboard gear, older US machinery and a large share of imported equipment built for 60 hertz export markets. NEMA MG-1 allows a 440 volt nameplate up to 484 volts, and plenty of 480 volt services read higher than that at light load. Single-phase and three-phase, 10 through 60 amps.
Equipment carrying a 440 volt nameplate reaches a US plant floor by three different routes.Marine and shipboard. 440 volts at 60 hertz is the standard shipboard distribution voltage worldwide, so pumps, winches, compressors, switchboards and test benches pulled off vessels arrive rated 440. Shipyards, marine repair shops and dockside service bays run them from a 480 volt shore service.Older US industrial. Motors, machine tools, presses, cranes and elevator gear built to the earlier 220/440 volt standard are still in daily service and still get rebuilt rather than replaced. The 230/460 designation replaced that standard decades ago; the equipment is still working.Imported machinery. Injection molding, packaging, printing, woodworking and food processing equipment sourced from Asian builders is frequently specified at 440 volts 60 hertz for export, along with the drives and control transformers inside it.The same pair comes up on VFD-fed loads. Many drives and servo supplies list an input window that tops out at 440 or 460 volts, which makes the drive, not the motor, the part that limits what the incoming service can be.