Transformer Efficiency and Losses:
A transformer is an electrical device that transfers electrical energy between two or more circuits through electromagnetic induction. It has two main components: the primary winding and the secondary winding, which are magnetically coupled together. Transformers are widely used in power transmission and distribution systems to step up or step down voltage levels.

Efficiency of a Transformer:
The efficiency of a transformer is defined as the ratio of output power to input power. It determines how effectively the transformer converts electrical energy from the primary side to the secondary side. The efficiency of a transformer is given by the formula:

Efficiency = (Output Power / Input Power) x 100%

When a transformer is operating at its full load, the efficiency is maximum, which means it is converting most of the input power to the output power without significant losses.

Losses in a Transformer:
There are two main types of losses in a transformer: iron losses and copper losses.

1. Iron Loss:
Iron loss, also known as core loss, is caused by the magnetic properties of the core material. It consists of two components: hysteresis loss and eddy current loss.

- Hysteresis Loss: Hysteresis loss is due to the reversal of magnetization in the core material as the alternating current flows through the windings. It results in energy being dissipated as heat. Hysteresis loss is directly proportional to the frequency and the volume of the core material.

- Eddy Current Loss: Eddy current loss is caused by the currents induced in the core material due to the alternating magnetic field. These currents circulate within the core and result in energy dissipation as heat. Eddy current loss is directly proportional to the square of the frequency and the resistance of the core material.

The iron loss in a transformer is constant and independent of the load. In this case, the iron loss is given as 1 kW.

2. Copper Loss:
Copper loss, also known as ohmic loss, is caused by the resistance of the windings. It is a result of the current flowing through the windings and is proportional to the square of the current.

- Copper loss = (I^2) x R

Where I is the current flowing through the windings and R is the resistance of the windings.

Calculating Copper Loss:
Since the transformer is operating at its full load, the output power is equal to the input power. Therefore, the copper loss can be calculated using the formula:

Copper loss = Total Loss - Iron Loss

Given that the iron loss is 1 kW, the copper loss can be determined. The efficiency of the transformer at full load is maximum, so the copper loss is at its minimum.