# Autotransformer - power transferred by conduction/induction

1. Apr 17, 2012

### killerdevil

1. The problem statement, all variables and given/known data
Upon finding my max. rated output power, and after finding the power transferred by conduction, can i just use:
Output power - power transferred by conduction = to get my power transferred by induction?

or do i have to apply the formula where, S = E1I1 = E2I2?

3. The attempt at a solution

I am not sure if i did the question correctly, but in the answer given to me, they used "Output power - power transferred by conduction" to get power by induction. however, when i did my working using the formula "S = E1I1 = E2I2", my answer was different.

2. Apr 17, 2012

### Staff: Mentor

Hi killerdevil. There is a worked example at the foot of this page that will slay you.

3. Apr 17, 2012

### killerdevil

when they state power transformed, are they referring to the power delivered at by induction? therefore they use power conducted - power transformed = power conducted??

4. Apr 17, 2012

### Staff: Mentor

Let's work it out.

Their equation is: Power Transformed = Load × (1–K)

If K=1 you know we would be dealing with a 1:1 turns ratio, and you know for a 1:1 turns ratio that power by induction is going to be zero. What does their equation give for K=1? It says Power Transformed = 0.

So it looks like "power transformed" is that delivered by transformer action, i.e., by induction. https://www.physicsforums.com/images/icons/icon14.gif [Broken]

Last edited by a moderator: May 5, 2017
5. Apr 18, 2012

### killerdevil

so when does the equation for conduction comes in? how is induction related to conduction? what is the difference between power delivered by conduction and power delivered by induction?

6. Apr 18, 2012

### Staff: Mentor

When K=1, you saw that zero power is transformed by induction. Therefore all the power in the load is delivered by conduction directly from the mains--no transformer coil involved.

What power on the load side isn't due to induction must be due to conduction.