Auto-Transformer Formula help Please..

Thread Starter


Joined Apr 7, 2011
Hi All,

Im studying for a final & am having problems finding the formulas in my notes to solve the question below..

An auto-transformer is connected to a 230V a.c supply. the secondary voltage is 50V a.c and the load current is 8A. How much current flows to the common part of the winding??

Appriciate the formula to find the current flowing to common part of winding please guys?? (Final a week away & I have no more lectures beforehand)


Joined Mar 6, 2009
This is partly true for the auto-transformer - to the degree that it relates the input primary terminal current to the secondary terminal current but it doesn't tell you what the common current is in the 'shared' part of the winding. Jimkeith's method is correct.