POWER

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POWER
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Engines

• During the industrial revolution, steam engines
  were used to run machines in a factory, to move
  trains and boats
• In a factory, the flywheel of the steam engine
  was connected by canvas belts to a shaft that ran
  the length of the factory, high overhead
• Reaction Engines
• Newtons third law explains why reaction engines
  work --- jet rocket engines
• In a jet engine, the burnt mixture of air and
  fuel
• Rocket engines carry their own oxygen supply
• Nuclear Reactors
• Large amounts of energy are released when large
  atomic nuclei are split
• The reactor can move a ship and fulfill its
  electricity needs as well

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Engines

• Electrical Motors
• They change electrical energy into rotary motion
• Small motors deliver less than one horsepower ---
  fractional horse power motors
• They must carry their power source with them

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Transmission

• They are used to carry force and motion from the
  engine of a power system to the object to be
  moved (the load)
• Transmissions can be mechanical, hydraulic or
  electrical
• Mechanical Power Transmission
• Mechanical transmissions (sometimes called
  mechanisms) are very simple parts
• Gears, pulleys, cams, levers, and linkages
• Hydraulic Power Transmission
• They transmit force through a tubing that carries
  the fluid
• Pressure force on a liquid/area
• Pistons of different sizes can be used to obtain
  larger or smaller forces

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Transmission

• Electrical Power Transmission
• Alternating current, or ac is produced by
  generators at power plants
• Electricity changed to heat by the resistance in
  the wires is lost
• Transformers are used to change the voltage of
  the current
• Transmission lines from several generating
  stations are often joined in a grid
• Superconductivity holds promise for saving the
  loss of electricity in terms of heat
• Superconductivity is possible in materials that
  were cooled nearly to absolute zero --- a
  temperature at which molecules stop moving ---
  about 459 F

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Continuous/Intermittent Power Systems

• Continuous power systems are nearly always
  available, e.g. an internal combustion engine
• Intermittent power systems sometimes store energy
• Solar cells charge a battery when the sun shines
• The battery in a car is recharged by a generator
  called a alternator