The Operation of a Transformer

• What is a transformer?

  A device that changes voltage and current
• Why is a transformer designed?

  To reduce heat energy loss during transmission
• What are the main components of a transformer?

  • Primary coil
  • Secondary coil
  • Iron core

  
• Why is the soft iron core used in a transformer?

  It focuses and directs the magnetic field
• What is the characteristic of soft iron in transformers?

  It can easily be magnetised and demagnetised
• What is a step-up transformer?

  Has more turns in the secondary coil

  
• What happens in the primary coil of a transformer?

  An alternating current produces an alternating voltage
• What does the alternating current create inside the iron core?

  An alternating magnetic field
• What is the result of the changing magnetic field in the secondary coil?

  An e.m.f is induced
• What does the induced e.m.f produce?

  An alternating output voltage from the secondary coil
• What is the relationship between the output and input voltage in a transformer?

  Output voltage matches input voltage frequency

  
• What is the transformer equation?

  • \( V_s / V_p = N_s / N_p \)
  • Where:
  • \( N_s \) = turns in secondary coil
  • \( N_p \) = turns in primary coil
  • \( V_s \) = output voltage
  • \( V_p \) = input voltage

  
• What is a step-down transformer?

  Decreases the voltage of the power source
• Where is a step-up transformer used?

  Between power stations and transmission wires
• Where is a step-down transformer used?

  Between transmission wires and buildings
• If a step-down transformer has a primary voltage of 0.5 kV, what is its secondary voltage?

  100 V
• How many turns are needed in the secondary coil if the primary coil has 3000 turns?

  Calculate using transformer equation

  
• How do you calculate the number of turns in the secondary coil?

  Use the transformer equation

  
• What is the process to find the number of turns in the secondary coil?

  1. Use the transformer equation: \( V_s / V_p = N_s / N_p \)
  2. Rearrange to find \( N_s \)
  3. Substitute known values