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Alternating Current

Alternating Current. Industrial Technology Electrical Systems. Producing Direct Current. Often produced by batteries A steady stream of electrons flowing in only one direction From negative to positive. Transmitting Direct Current.

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Alternating Current

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  1. Alternating Current Industrial Technology Electrical Systems

  2. Producing Direct Current • Often produced by batteries • A steady stream of electrons flowing in only one direction • From negative to positive

  3. Transmitting Direct Current • It is not practical to transmit Direct Current power over long distances, such as from the power plant to your home. • A large amount of power is lost due to the resistance in the wire. • Direct Current cannot be stepped up or down • Extremely high voltages can be employed to overcome power loss, but it’s too dangerous to operate loads at that level

  4. Producing Alternating Current Alternating Current is produced via Electromagnetic Induction by rotating a coiled conductor within a magnetic field.

  5. Transmitting Alternating Current • Alternating Current (AC) is the most common voltage used in the business because AC permits efficient transmission of electrical power over long distances • Voltages can be stepped up and down in amplitude via Electromagnetic Induction in transformers.

  6. Direct Current vs. Alternating Current Unchanging: constant amplitude current flowing in only one direction, negative to positive Always Changing: constantly changing in amplitude and direction. Never staying at one constant amplitude. Current never flows in just one direction.

  7. A Sine Wave shows the value of induced voltage at any time during the rotation of the coil. • - AC is constantly changing in Amplitude (Voltage): positive and negative. • - The highest positive point above the reference line is the Positive Peak. • - The lowest negative point below the reference line is the Negative Peak. • The voltage from one extreme to the other is called Peak to Peak. • The Peak voltage is 5 volts. Peak to Peak voltage is 10 volts.

  8. AC Sine Wave Cycles • An Alternation is either a positive or negative variation in voltage. • A CYCLE is made up of a positive Alternation and a negative Alternation. It • represents one complete 360 rotation of the coil in the magnetic field. • A PERIOD is the time it takes to make ONE complete CYCLE of a waveform • WAVELENGTH is the distance it takes to make ONC complete CYCLE, but it can • start anywhere on the sine wave as long as it ends in the exact same spot.

  9. Frequency of a Sine Wave Frequency is the measure of the number of cycles produced in a 1 second period of time. Frequency is measured in Hertz. Sometimes the term Hertz and Cycles are used interchangeably. For instance 60 Hertz can also be called 60 Cycles. 1 1 Frequency is the inverse of Period (time). F = t and t = F

  10. Voltage MAX and Peak to Peak • Epeak or Emax – the maximum voltage value reached during one alternation of a Sine Wave • Epeak to peak – the maximum voltage value reached during both the positive alternation and the negative alternation of a Sine Wave. • Epeak to peak – is twice the value of Epeak

  11. Average Voltage • Instantaneous voltage – the voltage value at any one given instant of time (like a snapshot). There are an infinite number of instantaneous voltage values in a Sine Wave. • Eavg – is the average value of all instantaneous voltage values during one and only one alternation of a Sine Wave Eavg = Emax X 0.636 Note: the Average Voltage Value of a complete Sine Wave is zero!

  12. Effective Voltage and the Root Mean Square • Eeff – is the voltage that produces the same amount of heat in a resistor as the Direct Current voltage of the same value. Eeff= Emax X 0.707 • The Effective Voltage is the same value as the Root Mean Square (rms).

  13. What’s it all mean to me? The typical output from a duplex outlet is 120 VAC at 60 Hertz 120 VAC is actually 120 RMS Eeff = Emax X 0.707 = 170vac X 0.707 = 120.19vac 60 Hertz means 60 full Sine Wave Cycles has occurred in one second. That’s the Frequency.

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