Electric-Light
Senior Member
Devices that find use on 208v and 240v nominal lines are common enough that we experience performance and/or cost compromise from having to design them to accommodate both.
Resistive heating devices rated at 240v, but allows 208 and 240v use runs at 3/4 the power which is a performance compromise.
Motors: those meant for 208 and 240 service don't fully accommodate the +/- 6% plus expected drop as the usual min-max range is 196 to 254v. When operated at 196v service at service entry on 208v nom. service, the voltage at motor terminals can reasonably be 185v or so, which may not provide full starting torque, or draw excess current at full load or do not provide overload ability to what the name plate says.
When the service is 254v (240v + 6%), it will suffer higher losses no load or low load conditions.
They're usually rated 196-253v
In Europe and much of Asia, they're mostly using one system of 400Y/230 to do everything we do using
120/208/240/277/480 from 120/208, 120/240, 240/480(uncommon), 277/480
So, we got the funky 208v from a design centered around 120v, then they work their way down from 480v design and come up with 277v to let lighting and some misc loads piggy back from it.
Couldn't we just get rid of 240v single phase and just harmonize to 208y/120 and design motors optimized for 208v?
Resistive heating devices rated at 240v, but allows 208 and 240v use runs at 3/4 the power which is a performance compromise.
Motors: those meant for 208 and 240 service don't fully accommodate the +/- 6% plus expected drop as the usual min-max range is 196 to 254v. When operated at 196v service at service entry on 208v nom. service, the voltage at motor terminals can reasonably be 185v or so, which may not provide full starting torque, or draw excess current at full load or do not provide overload ability to what the name plate says.
When the service is 254v (240v + 6%), it will suffer higher losses no load or low load conditions.
They're usually rated 196-253v
In Europe and much of Asia, they're mostly using one system of 400Y/230 to do everything we do using
120/208/240/277/480 from 120/208, 120/240, 240/480(uncommon), 277/480
So, we got the funky 208v from a design centered around 120v, then they work their way down from 480v design and come up with 277v to let lighting and some misc loads piggy back from it.
Couldn't we just get rid of 240v single phase and just harmonize to 208y/120 and design motors optimized for 208v?