TABLE OF CONTENTS As defined earlier, the efficiency is simply the ratio of power output to power input. In a real transformer, the efficiency is always less than 100% owing to the two types of losses: the magnetic loss and the copper loss.
The magnetic loss, which is commonly referred to as the core loss, consists of eddy-current loss and hysteresis loss. For a given flux density and the frequency of operation, the eddy-current loss can be minimized by using thinner laminations. On the other hand, the hysteresis loss depends upon the magnetic characteristics of the type of steel used for the magnetic core. Since the flux, ? m ? in the core of a transformer is practically constant for all conditions of load, the core (magnetic) loss, P m ? is essentially constant. It is for this reason that the core loss is often referred to as the fixed loss.
The copper loss (also known as I 2 R loss or the electric-power loss) comprises the power dissipated by the primary and secondary windings. The copper loss, P cu, varies as the square of the current in each winding. Therefore, as the load increases, so does the copper loss. That is why the copper loss is also termed the variable loss.
The power output can be obtained simply by subtracting the core loss and the copper loss from the power input. This implies that we can also obtain power input by...
