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HVACR317 - Refrigeration

HVACR317 - Refrigeration. Electrical Fundamentals. Volts. The potential difference (EMF) between two points can be very high or very low. The unit of measurement used to indicate the strength of the EMF is the Volt. Typical voltages are 24 volts, 120 volts, 240 volts and 480 volts.

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HVACR317 - Refrigeration

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  1. HVACR317 - Refrigeration Electrical Fundamentals

  2. Volts • The potential difference (EMF) between two points can be very high or very low. • The unit of measurement used to indicate the strength of the EMF is the Volt. • Typical voltages are 24 volts, 120 volts, 240 volts and 480 volts.

  3. Simple Schematic

  4. Volts • Voltage can vary from microvolts to megavolts. • Microvolts = millionths of a volt • Megavolts = millions of volts

  5. Terminology • Potential Difference • Electromotive Force (EMF) • Voltage • All mean the same thing, and can be used interchangeably.

  6. Terminology • Electromotive Force is not electricity. EMF is the driving force that causes electrons to move from one atom to another. • Amperage is the quantity and intensity of electrons moving through a conductor. Also called Ampere, Amps, Current. • An Ammeter is used to measure electron flow in a wire.

  7. Terminology • When current flows through a conductor, a magnetic field is created. • The clamp-on ammeter is used to read current flow in a wire.

  8. Ammeter

  9. Amperage • The ammeter will read the current flow in one single wire, or the current flow in wires with the same potential. • The ammeter will read zero amps when clamped around two wires of different potential. • See the next page for a diagram of an ammeter showing a reading.

  10. Ammeter Reading

  11. Resistance • Resistance is anything offering opposition to the flow of electrons. • There are two types of resistance: pure and inductive.

  12. Pure Resistance • Pure Resistance – Opposition remains constant. • Examples – light bulbs, electric heater • Higher voltage increases amperage • Lower voltage decreases amperage • Increased resistance decreases amperage • Lower resistance increases amperage

  13. Inductive Resistance • Has low resistance at start-up, but increased resistance during operation. • Examples are: transformers, solenoid coils, motor windings.

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