Yes, it does work that we add up the watt ratings of each coil with tranformers. Completely flys in the face of what I just told you for what goes with panels.
Each half of a single phase transformer can connected many different ways sometimes splitting the winding, and sometimes keeping the winding intact by not using the center tap. Even though the center tap may be a physical break in the winding circuit forming the equivilent of two coils, those coils could just as easily have been just one continuous wind. As such, we rate the single phase transformer as a whole.
Beats me why when we take three transformers and install them in the same case, we then add their ratings to create the whole. I suppose someone in marketing looked at the cost of the three phase transformer and noticed that it cost three times as much and demanded that the ratings of each leg be added together giving it a name 3 times as big which matches the price. Yet, if the three phase transformer were listed for parallel connection, you could effectively connect the three phase transformer up to provide the full transformer rating on a single phase.
Let's not even get into autotransformer connections and ratings. Oops, I should have quit already.
