7.3.5 Transformers

• What is the primary function of a transformer in electrical systems?

  To change the voltage of alternating current (AC) electricity.
• What is a transformer?


  • An electrical device used to increase (step up) or decrease (step down) voltage.
  • Keeps power ideally constant.
• On what principle do transformers operate?

  Transformers operate on the principle of electromagnetic induction.
• What are the basic components of a transformer?

  • Primary coil
  • Secondary coil
  • Core
• What is the primary coil in a transformer?

  The coil that receives the input voltage from the power source.
• What is the function of the primary coil in a transformer?

  It creates a magnetic field when AC flows through it.
• What is the secondary coil in a transformer?

  The coil that delivers the transformed voltage to the load.
• How does the secondary coil function in a transformer?

  It induces a voltage through the changing magnetic field from the primary coil.
• What is the core of a transformer?

  The central part of the transformer, usually made of laminated iron or steel.
• What is the function of the core in a transformer?

  It provides a pathway for the magnetic flux and increases efficiency by reducing energy losses.
• What happens when alternating current is applied to the primary coil of a transformer?

  An AC voltage creates a changing magnetic field around the coil.
• How does the changing magnetic field affect the secondary coil?

  The changing magnetic field induces a voltage in the secondary coil due to electromagnetic induction.
• What are the key transformer equations?

  1. Voltage Ratio:

  \[

  \frac{V_p}{V_s} = \frac{N_p}{N_s}

  \]

  2. Power Conservation:

  \[

  V_p \times I_p = V_s \times I_s

  \]
• What does the voltage ratio equation in transformers represent?

  The ratio of the voltages in the primary and secondary coils is proportional to the ratio of the number of turns in the coils.
• What does the power conservation equation in transformers indicate?

  Ideally, the power input to the transformer equals the power output, ignoring losses.
• What is a step-up transformer?

  • Increases the voltage from primary to secondary coil.
  • Has more turns in the secondary coil than in the primary coil.
• Where are step-up transformers commonly used?

  In power transmission lines to reduce energy loss over long distances.
• What is a step-down transformer?

  • Decreases the voltage from primary to secondary coil.
  • Has more turns in the primary coil than in the secondary coil.
• Where are step-down transformers commonly used?


  In power adapters for household devices.
• What are the applications of transformers?

  • Power transmission: Step up voltage for long-distance transmission and step down for safe distribution.
  • Electrical appliances: Adapt voltage levels for devices.
  • Audio systems: Match impedance levels between components.
• What is the efficiency of transformers?

  Transformers are highly efficient, often over 95%.
• What causes losses in transformers?

  Core losses due to hysteresis and eddy currents, and copper losses from wire resistance.
• How can transformer losses be reduced?

  • Use laminated cores to minimize eddy current losses.
  • Use high-quality core materials.
  • Reduce resistance in coils to minimize copper losses.