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Objectives

Objectives. When you have completed this session, you should be able to: Describe the fundamentals of electricity. State how electrical power is created and distributed. State the safety practices associated with electricity.

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Objectives

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  1. Objectives When you have completed this session, you should be able to: • Describe the fundamentals of electricity. • State how electrical power is created and distributed. • State the safety practices associated with electricity. • Describe the difference between alternating current and direct current. • Explain basic electrical theory. • Define voltage, current, resistance, and power and describe how they are related. • Use Ohm’s law to calculate the current, voltage, and resistance in a circuit. • Use the power formula to calculate how much power is consumed by a circuit. • Describe the differences between series and parallel circuits and calculate circuit loads for each type. Basic Electricity 03106-13

  2. Kickoff Activity Basic Electricity 03106-13

  3. 1.1.0 Power Generation PRIMARY POWER GENERATION METHODS Basic Electricity 03106-13

  4. 1.1.0 Transmission and Distribution Power transmission, distribution, and delivery to a residence. Basic Electricity 03106-13

  5. 1.2.0 Electrical Current Effects • The typical effects of electrical shock on the human body. Warning! High voltage, defined as 600V or more, is almost ten times as likely to kill as low voltage. On the job, you spend most of your time working on or near lower voltages. However, lower voltages can also kill. For example, portable, electrically operated hand tools powered by 120V can cause severe injuries or death if the frame or case of the tool becomes energized. Many electrical accidents can be prevented by following proper safety practices, including the use of ground fault circuit interrupters and proper grounding. Basic Electricity 03106-13

  6. 1.2.1 Safety Practices • Shut off electricity at the source if possible. • Lockout and tag the power switch. • Use a voltmeter to verify that power is off. • Use protective equipment such as rubber gloves. • Use insulated tools and inspect the cord before use. • Use a ground fault circuit interrupter (GFCI) with power tools. • Short components to ground before touching de-energized wires. • Do not kneel on the ground when making voltage measurements. When it is necessary to test a live circuit, keep one hand outside the unit if possible. • Remove metal jewelry such as rings and watches. Basic Electricity 03106-13

  7. 1.3.0 AC and DC Power • Automobiles, cell phones, laptops, calculators, and flashlights are good examples of devices that use DC voltage. • Alternating current is supplied by the local utility, and HVAC/R equipment requires it. However, many modern units use motors or electronic circuit boards that do require DC voltage. Rather than using batteries, which need to be replaced or recharged, such units contain special electronic circuits called rectifiers that convert AC power to DC. Basic Electricity 03106-13

  8. 1.3.0 Magnetism and Electricity Electromagnetism explains how motors and generators work. Basic Electricity 03106-13

  9. 2.1.0 An Electrical Circuit • A voltage source • A load device • A control device to open and close the circuit • Conductors to carry the current Basic Electricity 03106-13

  10. 2.2.0 Ohm’s Law • The formula for calculating voltage, current, or resistance, in a graphical format Basic Electricity 03106-13

  11. 2.3.0 The Complete Power Formula How much current will a 1,600W heater draw in a 120V circuit? Basic Electricity 03106-13

  12. 2.4.0 Types of Circuits • Basic Circuit Types Basic Electricity 03106-13

  13. 2.4.2 Parallel Loads Circuits with two and three parallel loads Basic Electricity 03106-13

  14. Wrap Up – Trade Terms Review Alternating current (AC): An electrical current that changes direction on a cyclical basis. Ampere (A): The unit of measurement for current flow. Direct current (DC): An electric current that flows in one direction. Basic Electricity 03106-13

  15. Wrap Up – Trade Terms Review Ohms (Ω): The unit of measurement for electrical resistance. Volt (V): The unit of measurement for voltage. Voltage:  A measure (in volts) of the electrical potential for current flow. Watts (W): The unit of measure for power consumed by a load. Basic Electricity 03106-13

  16. Wrap Up NEXT SESSION… • Electrical Measuring Instruments; Load Devices • Review Sections 3.0.0 through 4.1.2. Complete the 1.0.0, 2.0.0, and 3.0.0 Section Reviews. Basic Electricity 03106-13

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