Legislation without thought.
You cannot define energy savings without defining the load profile (current versus time).
There are two types of losses in a transformer core (steel), and windings (conductor). Core losses exist for as long as the transformer is energized. Winding losses exist based on the amount of current flowing through the transformer. Ignoring everything else, due to I^2xR, a transformer loaded to %50 will have only %25 of the winding losses of a fully loaded transformer.
Now using some daily values for an office: 12hr @ 100A, 4hr @ 50A, 8hr @ 0A
Pick a standard loss 75KVA transformer 480-208Y/120, FLA-208A, full load winding loss-2700W, core loss-450W; an energy savings design 75KVA FLA=208A, full load winding loss-1,350W, core loss-585W: and a standard 45KVA, FLA-125A, full load winding loss-1,620W, core loss-270W.
Applying the load profile
Total Energy lost KWHr = (Core losses X 24hr) + ((actual load/full load)^2 X winding losses X HR)
Standard 75KVA Total losses = 18.42KWHR
Energy Savings 75KVA Total Losses = 18.08KWHR
Standard 45KVA Total Losses = 19.96KWHR
Results: A lightly loaded transformer is inherently energy efficient.
[This message has been edited by JBD (edited 03-24-2003).]
