APPARATUS

• Practical transformer


  A kind of transformer that transfers energy between two coils and a magnetic core
• Practical transformer


  It is the exact opposite of Ideal Transformers since it exists in real life
• Practical transformer


  It accounts for losses since there is no 100% efficiency
• Characteristics of a practical transformer

  • Electromagnetic induction for voltage transformation
  • Input and output power efficiency
  • Static nature and absence of air resistance and friction
  • Efficiency
  • Leakage inductance
  • Saturation
  • Copper losses in windings
  • Core losses from eddy current and hysteresis
  • Temperature rise
• Electromagnetic induction for voltage transformation

  Transformers rely on Faraday's Law of Electromagnetic Induction
• Input and output power efficiency

  A transformer maintains a certain frequency that must be equal to the input and output power
• Static nature and absence of air resistance and friction

  Transformers are static in nature and not prone to mechanical wear and have no loss due to air resistance and friction
• Efficiency


  A practical transformer has losses that reduce its efficiency, but real-world transformers have efficiencies above 90%
• Leakage inductance


  Affects the performance of the transformer, especially at high frequencies, due to magnetic flux that leaks on the winding
• Saturation


  When the magnetic field becomes too high, it will cause saturation and the transformer cannot handle higher voltage
• Copper losses in windings

  Energy is lost in the form of heat as it flows through the copper conductor
• Core losses from eddy current and hysteresis

  Eddy currents are tiny circulating currents in the transformer core, and hysteresis is the energy loss during magnetization and demagnetization cycles
• Temperature rise


  Different losses in the transformer are in the form of heat, which causes the temperature to rise and can damage insulation and affect efficiency
• Differences between ideal transformer and practical transformer

  • Ideal transformer has zero core losses, copper losses, and 100% efficiency, while practical transformer has finite losses and less than 100% efficiency
• Leakage flux


  Magnetic flux that does not link both the primary and secondary windings entirely
• Factors that affect leakage flux

  • Imperfect magnetic core
  • Spacing between windings
  • Non-ideal insulation
  • Fringing
  • Winding distribution
• Leakage flux consequences

  Energy losses, reduced efficiency, and voltage regulation
• Magnetic core


  Helps efficiently transfer energy from primary to secondary winding, but leakage flux represents energy losses and inefficiencies
• kVA


  Measure of apparent power, product of voltage and current
• kW


  Measure of real power, used by the load
• Standard kVA ratings of transformers

  • Residential: 5, 7.5, 15, 20 kVA
  • Commercial: 30, 45, 75 kVA
  • Industrial: 500, 750, 1000 kVA
• Types of single-phase transformer ratings


  • Encapsulated
  • Ventilated
  • Totally enclosed and non-ventilated
• Types of three-phase transformer ratings


  • Encapsulated
  • Ventilated
  • Totally enclosed and non-ventilated
• Types of transformer tests

  • Winding resistance test
  • Insulation resistance test
  • Temperature rise test
  • Partial discharge test
  • Impulse voltage withstand test
  • Short-circuit withstand test
  • Transformer oil test
• Types of transformer loading

  • Full load
  • Overload
  • Underload
• Transformer load


  The quantity of power that moves through the transformer
• Full load capacity


  The maximum amount of current that can be transmitted by the transformer
• Safe load capacity


  75-80% of the maximum capacity that can be transmitted by the transformer
• Ideal transformer on no load

  Has no primary and secondary winding resistance, carries infinite amount of magnetic flux with no saturation, and neglects eddy current and hysteresis
• No-load transformer


  Will indicate a small current flowing through the primary winding even with the secondary winding open-circuited
• Turns ratio of a transformer


  Total induced voltage in each winding is proportional to the number of turns in that winding
• Voltage ratio of a transformer

  Equal to the turn ratio of the transformer
• Current


  Inversely proportional to both the voltage and the number of turns
• Load power


  The amount of power being drawn from the transformer
• Transformer rating


  The rated capacity of the transformer
• Overloading


  Can cause the transformer to overheat
• Underloading


  Can cause the transformer to operate at lower efficiency
• Power factor


  The ratio of apparent power (kVA) to real power (kW), a measure of how efficient a transformer is
• Importance of monitoring transformer loading

  • Ensuring safety
  • Maximizing efficiency
  • Predictive maintenance
• Ways to optimize transformer loading for efficiency


  • Load balancing
  • Load shedding
  • Upgrading transformers
  • Power factor correction