Domestic/Small Industrial, Distribution Transformer Connections

[John McLean]

As I understand it, the supplies to domestic dwellings in USA, are derived
from transformer secondary windings for the 220V, and with the centre
grounded, for the 110V supply to lower power devices, e.g. fridges etc.

What is the transformer configuration, for say a pole mounted transformer to
a dwelling, would this be 2 phase with centre grounded? and phase
displacement of 120 degrees
And what is the standard small industrial transformer setup at low voltage,
is this a delta star transformer?

Jaymack

 

[Ben Miller]

As I understand it, the supplies to domestic dwellings in USA, are derived
from transformer secondary windings for the 220V, and with the centre
grounded, for the 110V supply to lower power devices, e.g. fridges etc.

What is the transformer configuration, for say a pole mounted transformer
to
a dwelling, would this be 2 phase with centre grounded? and phase
displacement of 120 degrees
And what is the standard small industrial transformer setup at low
voltage,
is this a delta star transformer?

Jaymack

Take a look at http://www.bmillerengineering.com/elecsys.htm
That will answer a lot of your questions about the US configurations. It
does not show the transformer primaries, just the secondaries.

Ben Miller