Part 3

• What is the purpose of load-flow analysis?


  To analyze steady-state performance of power systems
• What does load-flow analysis study?

  Effects of changes in equipment configuration
• How is load-flow analysis performed?

  Using numerical techniques and computers
• What are the key components reviewed in electrical engineering basics?

  • Resistance
  • Phase
  • Phasor
  • Phase Difference
  • Inductance
  • Inductive Reactance
  • Inductor
  • Capacitor
  • Capacitance
  • Capacitive Reactance
  • RLC circuit
  • Steady-state operating conditions
• What is the SI unit of electrical resistance?

  Ohm (Ω)

  
• What does Ohm's law state?

  Current is proportional to voltage

  
• How is electrical resistance calculated using voltage and current?

  R = V / I

  
• What is the resistance in a circuit with 220V and 4A?

  55 Ω
• What is phase in the context of waves?

  An angle-like quantity representing wave cycles
• How is phase measured?

  In degrees or radians
• What is a phasor?

  A complex number representing sinusoidal voltages

  
• How is a phasor defined for a sinusoidal voltage?

  As V1∠θ1
• What does the phase difference measure?

  The angular relationship between two waves
• What is the phase difference when voltage leads current by 90°?

  Voltage leads current by a phase angle of 90°

  
• What is inductance?

  The tendency to oppose changes in current

  
• What is the SI unit of inductance?

  Henry (H)

  
• How is inductive reactance defined?

  As the ratio of peak voltage to peak current
• What is the formula for inductive reactance?

  $X_L =$$2\pi f L$
• How does inductive reactance relate to frequency?

  It is proportional to the frequency of AC

  
• What is an inductor?

  A passive component that stores energy in a magnetic field
• What is a capacitor?

  A device that stores electrical energy in an electric field
• What is capacitance?

  The effect of a capacitor characterized by a constant
• How is capacitance defined mathematically?

  $C =$$\frac{q}{V}$
• What is capacitive reactance?

  The opposition to AC current in a capacitor
• What is the formula for capacitive reactance?

  $X_C =$$\frac{1}{2\pi f C}$
• How does capacitive reactance relate to frequency?

  It is inversely proportional to the supply frequency

  
• What is an RLC circuit?

  • Contains resistance (R), inductive reactance (X_L), and capacitive reactance (X_C)
  • Impedance (Z) is defined as: $Z =$$\sqrt{R^2 + (X_L - X_C)^2}$
  • Voltage and current can peak at different times
• What is electric current?

  A flow of charged particles through a conductor
• How is electric current measured in SI units?

  In amperes (A)
• What defines steady-state operating conditions in a circuit?

  Current does not change with time

  
• How does steady-state differ in DC and AC analysis?

  DC is constant; AC parameters vary

  
• What are the types of power consumed in circuits?

  • Power consumed in a DC Circuit
  • Power consumed in a purely resistive AC Circuit
  • Net power consumed by a purely inductive AC load
  • Power consumed in an AC Circuit
  • Main Sources of Reactive Power
  • Power Triangle
  • Power Factor
• What is the formula for power consumed in a DC circuit?

  $P =$$VI$
• What is the power consumed in a purely resistive AC circuit?

  $P =$$VI \cos \theta$
• What is the power consumed by a purely inductive AC load?

  $P =$$VI \cos \theta =$$0$
• What happens to energy in an AC network?

  It is borrowed and returned to its source
• What are the main sources of reactive power?

  • Long Transmission lines
  • Transformers
  • Motors
  • Capacitors
• What is the value of VR in the given equation?

  150∠30° V

  
• How do you calculate peak current from VR and R?

  Peak current = VR / R
• What is the peak current when VR = 150∠30° V and R = 50?

  3∠30° A