Basic Aircraft Maintenance Training: Power

Power in an Electrical Circuit

• Power measures the rate of energy consumption or conversion in a system, applicable to both mechanical and electrical systems.
• The formula for power is expressed as: P = E / t, where:
  • P = Power (Watts)
  • E = Energy (Joules)
  • t = Time (Seconds)
• Power is quantified in watts (W), equivalent to 1 joule per second of energy conversion.
• Example calculation: If 300 J of energy is consumed in 10 seconds, power is calculated as:
  • P = 300 J / 10 s = 30 W
• The term "watt" is named after James Watt, who measured the power output of a horse to evaluate steam engine performance.
• One horsepower (hp) is defined as the ability to move 33,000 pounds by 1 foot in 1 minute, which translates to 550 ft-lb/sec.
• For electrical systems, an electric motor rated at 1 horsepower requires 746 watts of electrical energy.
• Common derived units of power include:
  • Milliwatt (mW): 1 W = 1000 mW
  • Kilowatt (kW): 1 kW = 1000 W
  • Megawatt (MW): 1 MW = 1,000,000 W
  • Gigawatt (GW): 1 GW = 1,000,000,000 W