Secondary windings

[dicklaxt]

Looking at a Jefferson single phase transformer with 120/240 secondary windings,,,,,,,,,,,,,,the connection diagram states for 120V service to interconnect X1 to X3 and X2 to X4 then secondary connection for 120V is X1 - X4.

Now the question is why put the two secondary windings in parrallel,why not just leave it alone and connect the needed secondary lines to either X1- X2 or X3 - X4?

The only reason I can see is that if not connected in parrallel,then you would still have the possibility of 240V across X1-X4 when you didn't want it if X2 - X3 somehow got shorted.

What do the experts say?

dick

 

[david luchini]

I believe if you only connected to X1-X2 for the 120V, you'd only be getting half of the transformer's rated VA. By paralleling the secondary windings you get the full rating at 120V.

 

[dicklaxt]

I think you are right, good thinking.........

dick

 

[LarryFine]

That is correct.

 

[david luchini]

I wonder if the code would allow the secondary windings to be protected separately? For example, on a 10kVA, 480-240/120V transformer, could you protect it with a 50A c/b on the primary, and two 60A c/b's on the secondary, one for each winding?