For procedures, see your electrical laboratory manual.

Title: The Single Phase Transformer

Aim

1. To verify that the voltage ratio between the primary voltage and secondary voltage of a transformer is equal to the turns winding ratio.
2. To study the characteristics of a transformer on no-load and on load.

Apparatus

1. One Variac 0 - 270V, 8A, 2KVA
2. One Transformer
3. Two AC voltmeter 0 - 300V
4. One AC voltmeter 0 - 100V
5. Two AC ammeter 0 - 10A
6. One AC ammeter 0 - 1A
7. Wattmeter
8. Load resistance bank

Theory

The transformer is a static electrical machine that transfers electrical energy from one level to another through the principle of laws of induction. At the end of the transformation, the frequency of the transformer remains constant. The higher the number of turns, the higher the voltage.

First Law of Faraday's Electromagnetic Induction state that whenever a conductor is placed in a varying magnetic field emf are induced which is called induced emf, if the conductor circuit is closed current are also induced which is called induced current.

Or

Whenever a conductor is rotated in a magnetic field emf is induced which are induced emf.
The Second Law of Faraday's Electromagnetic Induction states that the induced emf is equal to the rate of change of flux linkages (flux linkages is the product of turns, n of the coil, and the flux associated with it).

Types of transformers

1. Single Phase Transformer
2. Three Phase Transformer
3. Power Transformer
4. Current Transformer
5. Variable Transformer
6. Voltage Transformer
The most common types are the single-phase and three-phase transformer.

The variac which varies voltage is an autotransformer.
The transformer is divided into two main parts
1. Laminated iron core
2. The windings

Types of losses that occur in a transformer

1. Core losses or iron losses
2. Copper losses or heat losses
3. Eddy current losses
4. Hysteresis losses

Answers to Questions:

1. Copper losses result from Joule heating and so are also referred to as "I squared R losses", in reference to Joule's First Law. This states that the energy lost each second, or power, increases as the square of the current through the windings and in proportion to the electrical resistance of the conductors.

2. Copper Losses can be determined by the product of the square of the current and the resistance the copper = I²·R

3. Transformers are rated in kVA because the losses occurring in the transformers are independent of the power factor.