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Transformer

Transformer

Made of

Copper Iron Steel

Brief description

A transformer is a passive electrical device that transfers electrical energy from one electrical circuit to another, or multiple circuits. It is primarily used to increase (step-up) or decrease (step-down) the voltages of alternating current (AC) without changing the frequency.

Use / Function

  • Power Transmission: Increasing voltage for efficient long-distance transport (minimizing heat loss in wires).
  • Power Distribution: Decreasing voltage to safe levels for domestic and industrial use.
  • Impedance Matching: Maximizing power transfer between different electrical components.
  • Isolation: Preventing direct electrical connection between two circuits for safety.

Operating principle

The transformer works on the principle of Faraday’s Law of Induction, specifically Mutual Induction.

  1. Primary Coil: Alternating current flows through the primary coil (input), creating a constantly changing magnetic field around it.
  2. Magnetic Core: This changing magnetic field is channeled through a high-permeability iron core.
  3. Secondary Coil: The changing magnetic field passes through the secondary coil (output), which induces a voltage in it.
  4. Voltage Ratio: The ratio of the input voltage to the output voltage is equal to the ratio of the number of turns in the primary coil to the number of turns in the secondary coil ($V_p/V_s = N_p/N_s$).

How to create it

Basic Transformer

  1. Core Construction: Create a closed loop or “O” shape of Iron. For efficiency, use thin, insulated sheets of Steel (laminations) stacked together to reduce energy loss from eddy currents.
  2. Primary Winding: Wrap insulated Copper wire around one side of the core.
  3. Secondary Winding: Wrap insulated copper wire around the other side (or on top) of the core. The number of turns depends on whether you want to step the voltage up or down.
  4. Insulation: Ensure the coils are well-insulated from the core and each other.

Materials needed

Variants and improvements

  • Step-up Transformer: More turns on the secondary than the primary (increases voltage).
  • Step-down Transformer: Fewer turns on the secondary than the primary (decreases voltage).
  • Auto-transformer: Uses a single coil with a “tap” point, sharing part of the winding for both input and output.
  • Three-phase Transformer: Used in industrial power grids for high-capacity transmission.

Limits and risks

  • AC Only: Transformers do not work with steady Direct Current (DC), as they require a changing magnetic field.
  • Heat: Energy is lost as heat in the wires (copper loss) and the core (iron loss). Large transformers require cooling oil.
  • Saturation: If too much current is used, the core can become magnetically “full” (saturated), leading to inefficiency and overheating.
  • High Voltage: Stepping up voltage creates extreme electrocution risks and can cause insulation to fail (arcing).