Question

Explain the basic concept of transformer. Mention any two different types of transformers.

Hint:

Transformers work strictly with alternating current (AC) because they rely on a constantly changing magnetic flux ($\frac{d\Phi}{dt}$) to induce voltage. If connected to a steady DC source, the flux remains constant, no back-emf is induced, and the high current will burn out the primary winding.
For more detailed calculations, please refer to pages 3 and 4 of “Electrical_Technology.pdf”.

Answer 1

Step 1: Explaining the Transformer Concept:
A transformer is a static (stationary) electrical device that transfers alternating current (AC) electrical energy from one circuit to another at a constant frequency through electromagnetic induction.

Step 2: Core Working Principle:

• It consists of two or more insulated copper windings (Primary and Secondary) wound around a common laminated silicon-steel magnetic core.
• When an alternating voltage ($V_1$) is applied to the primary winding, it draws an alternating current that produces a changing magnetic flux ($\Phi$) in the core.
• This changing flux links with the secondary winding, mutually inducing an alternating electromotive force ($E_2$) in it via Faraday's Law of Electromagnetic Induction.
• The relationship is governed by the transformation ratio: $$\frac{V_1}{V_2} = \frac{N_1}{N_2} = K$$ Where $N_1$ and $N_2$ represent the number of turns in the primary and secondary windings, respectively.

Step 3: Two Key Types of Transformers (Classified by Function):

• Step-Up Transformer: A transformer that increases the voltage level ($V_2 > V_1$, $N_2 > N_1$). It is installed at power generation plants to step up generated voltages for efficient long-distance transmission.
• Step-Down Transformer: A transformer that decreases the voltage level ($V_2 < V_1$, $N_2 < N_1$). It is used in local distribution grids and consumer chargers to lower high grid voltages to safe household levels (e.g., $230\text{ V}$ or $12\text{ V}$).