277/480 & 265/460

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iwire

Moderator
Staff member
Location
Massachusetts
They are the same voltages the higher is the nominal voltage, and the lower voltage the nameplate voltage.

ANSIC841.jpg
 

kingpb

Senior Member
Location
SE USA as far as you can go
Occupation
Engineer, Registered
The 480Y/227V would be the system nominal voltage.

I would imagine the 460/265, although I don't think I've seen it displayed this way, is probably the motor rated terminal voltage.
 

Besoeker

Senior Member
Location
UK
They are the same voltages the higher is the nominal voltage, and the lower voltage the nameplate voltage.

ANSIC841.jpg

Five different voltages at LV.
From a British POV that seems just such a muddle.
We get by with just 400V three phase from which 230V single phase is derived.
Why do you need/have so many?
I can understand the 208/120.
But then what needs 208 or 240 or 277?
 

hurk27

Senior Member
The evolving of standards over the years, simply you can not expect everyone to go out and buy all new equipment just because you want to no longer supply a system voltage, and as our power system has gotten more and more away from delta's and offer more Y supply's you end up having the many voltages offered.

To add years ago deltas were more common, and 4-wire deltas took care of the 120 volt need as well as the 240 volt 3-phase, but now the 208/120 is the norm, and 480/277 which are both Y services.
 
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steve66

Senior Member
Location
Illinois
Occupation
Engineer
Five different voltages at LV.
From a British POV that seems just such a muddle.
We get by with just 400V three phase from which 230V single phase is derived.
Why do you need/have so many?
I can understand the 208/120.
But then what needs 208 or 240 or 277?

120V is the standard Line to neutral voltage here (for residential customers).

From that voltage, a 3 phase system gives a line to line voltage of 208V, and a single phase system gives a L-L voltage of 240V.

It makes sense for industrial customers to have a higher voltage, therefore the 480V three phase system that gives a L-N voltage of 277 volts.

The only real muddle I see is that sometimes power companies try to save a few bucks, and we wind up with things like 240/120V 3 phase systems, and 208/120V single phase systems, high leg delta's, etc.

Steve
 

Besoeker

Senior Member
Location
UK
The evolving of standards over the years, simply you can not expect everyone to go out and buy all new equipment just because you want to no longer supply a system voltage,
Nor would I expect them to.
But maybe new domestic equipment and appliances could be manufactured to all operate off the same voltage.
That could eventually simplify distribution at that level.
 
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