# AC Circuits - Transformers

(a)

A small mains step-down transformer used to power 12V apparatus has the label below:

If the primary and secondary winding resistances are 125ohms and 0.7ohms respectively, calculate the transformer's copper losses at full load.

(b)

A large power transformer has a turns ratio N1/N2 of 1.5. When the primary voltage is 400V and it is connected to a resistive load its secondary current is 100A.

(i)

Calculate the required value of source resistance of the supply to give maximum power transfer.

(ii)

If total losses in the transformer amount to 4kW for the conditions in (i) then calculate the transformer's efficiency.

https://brainmass.com/physics/ac/ac-circuits-transformers-263572

#### Solution Preview

(a)

A small mains step-down transformer used to power 12V apparatus has the label below:

If the primary and secondary winding resistances are 125ohms and 0.7ohms respectively, calculate the transformer's copper losses at full load.

Solution: The maximum secondary current can be computed by looking at the ...

#### Solution Summary

This posting contains the solution to the given problems. The expert calculates the required value of source resistance.