Lecture Notes: How Transformers Work

Introduction

• Presented by Paul from TheEngineeringMindset.com
• Part of a series on electrical engineering
• Topics covered:
  • Creating a magnetic field with electricity
  • Use of alternating current (AC) in transformers
  • Basic transformer operation
  • Step-up and step-down transformers
  • Three-phase transformers

Types of Electricity

• AC (Alternating Current) and DC (Direct Current)
• Transformers only work with AC because:
  • AC generates a changing magnetic field
  • This change induces electromotive force (EMF) in nearby coils

Alternating Current

• AC generator connected to a closed loop creates alternating flow
• Sine wave pattern observed due to alternation
• Magnetic field changes with AC, inducing AC in the secondary coil

Transformer Basics

• Coils: Primary and secondary coils
• Magnetic Field:
  • Created by AC in primary coil
  • Induces current in secondary coil
  • Magnetic field intensity and polarity change is crucial

Transformer Efficiency

• Iron Core: Used to direct magnetic field between coils
  • Improves efficiency by minimizing wasted magnetic field
• Eddy Currents:
  • Causes energy loss as heat
  • Minimized by laminated iron sheets

Step-Up and Step-Down Transformers

• Step-Up Transformer:
  • Increases voltage, decreases current
  • More turns in secondary coil than primary
• Step-Down Transformer:
  • Decreases voltage, increases current
  • Fewer turns in secondary coil than primary
• Example: Power station uses step-up to transmit over distance, step-down near consumption areas

Three-Phase Transformers

• Used in commercial setups and power stations
• Can be made from three separate transformers or one unit
• Configuration:
  • Coils sit concentrically
  • Insulated from each other
  • Common configuration: Delta Y (Delta Star)
    • Primary side: Delta
    • Secondary side: Y (Star)
    • Center grounded for neutral line

Conclusion

• Focus on understanding basic operation
• Advanced topics like connections and calculations will be covered later

Additional Resources

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• Video links and further reading available in video description