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Chapter 3

Chapter 3. What is Power? Power is the amount of work being done over a period of time. PROLOGUE 3. When energy is converted, transmitted, and/or controlled to do useful work, we call this a power system POWER -is the amount of work being done over a period of time

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Chapter 3

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  1. Chapter 3 What is Power? Power is the amount of work being done over a period of time.

  2. PROLOGUE3 • When energy is converted, transmitted, and/or controlled to do useful work, we call this a power system • POWER-is the amount of work being done over a period of time • One horsepower is the energy needed to lift 33,000 lb. I ft. in 1 minute • Hp= work/ time in minutes x 33,000 • WORK is the application of force which moves an object work= distance x force

  3. What is Power? 3 It can be measured by the formula Power = work/time It can also be measured as P = D x F/ t D is distance, F is force, and t is time Horsepower: standard unit of power Work = Distance x Force Hp = work/time in minutes X 33000

  4. Power Systems3 Are machines that are used to convert energy into movement . Power is needed in our technological society and in our transportation systems. Power systems come in many different shapes, sizes, and performance of jobs. Three basic power systems are electrical, mechanical, and fluid.

  5. Electrical Systems 3 Are systems using electrical energy to do work. We need electrical systems for transportation systems. For example, the subway, Maglev, and elevator.

  6. Measuring Current3 • Electrical power - watts. Amperage is the rate at which current flows through a conductor. measured with an ammeter. The formula sign for it is I. • Voltageis the pressure pushing the current through a conductor. They are measured with a voltmeter. The formula sign for it is E. • Resistanceis the opposition to current flow through a conductor. It is measured in ohms, with an ohmmeter. The formula sign for it is R. Ohm’s law can mathematically compute amperes, volts, and ohms. The formula is Voltage = Amperage x Resistance

  7. Measuring Electrical Power3 Is measured in watts. Wattage is the measurement of power produced by the flow of current under pressure. Wattage = Amperage x Voltage

  8. Mechanical Systems3 Mechanical energy is the energy of motion. When it is converted, it is referred to as mechanical power. Machines are devices used to manage mechanical power. Bicycle, paddleboat.

  9. Fluid Systems3 Are those systems that do work using the energy found in liquids and gases. It can accomplish the movement of very heavy objects. Two types of fluid power systems: pneumatic and hydraulic. Pneumatic systems use a gas to transmit power and to control power. Hydraulicsystems use a liquid to transmit and control power. It has an advantage over other forms of power; mechanical power is often slow, electrical power is often expensive, but fluid power is easy to control and operate.

  10. Measurement Conversion3 Two measuring systems used in the United States are: U.S. customary- inches, yards, miles SI metric- millimeters, centimeters meters

  11. Basic Elements of All Power Systems3 Electrical, mechanical, and fluid power systems all have the same basic functions. Source of energy Conversion method Transmission path Control systems Measuring devices Output or a load

  12. Summary3 • Power is energy that has been converted. When energy is converted, transmitted, and controlled to do useful work, it is referred to as a power system. Power is measured in a standard unit known as horsepower. There are three basic power systems in our society. They are electrical systems, mechanical systems, and fluid systems.

  13. Key Words3 • Amperage • Ammeter • Voltmeter • Resistance • Ohmmeter • Fluid Power Systems • Pneumatic • Hydraulic

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