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PRINCIPLES OF ELECTRICITY
INTRODUCTION TERMINOLOGY OHM’S LAW CIRCUITS POWER & ENERGY DIRECT CURRENT ALTERNATING CURRENT ELECTRICITY CONSTITUTES A FORM OF ENERGY THAT OCCURS NATURALLY ONLY IN UNCONTROLLED FORMS: LIGHTNING STATIC ELECTRICITY GALVANIC REACTIONS
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PRINCIPLES OF ELECTRICITY
INTRODUCTION TERMINOLOGY CURRENT POTENTIAL RESISTANCE OHM’S LAW CIRCUITS POWER & ENERGY DIRECT CURRENT ALTERNATING CURRENT DESCRIPTION: ELECTRON FLOW, THE NUMBER OF ELECTRONS FLOWING PAST A GIVEN POINT. UNITS: AMPHERES (AMPS, A) 1 AMP = 1 COULOMB PER SECOND 1 COULOMB = 6.28 X 1018 ELECTRONS. CURRENT
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PRINCIPLES OF ELECTRICITY
INTRODUCTION TERMINOLOGY CURRENT POTENTIAL RESISTANCE OHM’S LAW CIRCUITS POWER & ENERGY DIRECT CURRENT ALTERNATING CURRENT DESCRIPTION: VOLTAGE, EMF, V OR E THE FORCE DRIVING THE CURRENT. THIS ELECTRON MOVEMENT IS CAUSED BY CREATING A HIGHER POSITIVE ELECTRIC CHARGE AT ONE POINT ON A CONDUCTOR THAN EXISTS AT AN OTHER. UNITS: VOLTS POTENTIAL
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PRINCIPLES OF ELECTRICITY
INTRODUCTION TERMINOLOGY CURRENT POTENTIAL RESISTANCE OHM’S LAW CIRCUITS POWER & ENERGY DIRECT CURRENT ALTERNATING CURRENT DESCRIPTION: RESISTANCE (R) ELECTRICAL TERM FOR FRICTION. RESISTANCE TO FLOW OF CURRENT IN AN ELECTRIC SYSTEM. UNITS: OHMS RESISTANCE
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PRINCIPLES OF ELECTRICITY
INTRODUCTION TERMINOLOGY CURRENT POTENTIAL RESISTANCE OHM’S LAW CIRCUITS POWER & ENERGY DIRECT CURRENT ALTERNATING CURRENT CONDUCTORS: MATERIALS THAT OFFER A LOW RESISTANCE TO THE FLOW OF ELECTRIC CURRENT. PRECIOUS METALS: SILVER, GOLD & PLATINUM. COPPER ALUMINUM RESISTANCE
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PRINCIPLES OF ELECTRICITY
INTRODUCTION TERMINOLOGY CURRENT POTENTIAL RESISTANCE OHM’S LAW CIRCUITS POWER & ENERGY DIRECT CURRENT ALTERNATING CURRENT INSULATORS: MATERIALS THAT VIRTUALLY PREVENT THE FLOW OF ELECTRIC CURRENT. GLASS. RUBBER & PLASTIC: WIRE COVERING. PORCELAIN: LAMP SOCKETS. OIL: OIL-IMMERSED SWITCHES. RESISTANCE
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PRINCIPLES OF ELECTRICITY
INTRODUCTION TERMINOLOGY CURRENT POTENTIAL RESISTANCE OHM’S LAW CIRCUITS POWER & ENERGY DIRECT CURRENT ALTERNATING CURRENT PORCELAIN: LAMP SOCKETS.
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PRINCIPLES OF ELECTRICITY
INTRODUCTION TERMINOLOGY OHM’S LAW DESCRIPTION SAMPLE PROBLEMS CIRCUITS POWER & ENERGY DIRECT CURRENT ALTERNATING CURRENT CURRENT (I) = VOLTAGE (V) / RESISTANCE (R) DESCRIPTION: EXPRESSES THE RELATIONSHIP BETWEEN CURRENT, POTENTIAL & RESISTANCE. THE GREATER THE VOLTAGE, THE GREATER THE CURRENT. CONVERSELY THE GREATER THE RESISTANCE, THE SMALLER THE CURRENT. OHM’S LAW
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PRINCIPLES OF ELECTRICITY
INTRODUCTION TERMINOLOGY OHM’S LAW DESCRIPTION SAMPLE PROBLEMS CIRCUITS POWER & ENERGY DIRECT CURRENT ALTERNATING CURRENT AN INCANDESCENT LAMP HAVING A HOT-RESISTANCE OF 66 0HMS IS PUT INTO A SOCKET THAT IS CONNECTED TO 115-V SUPPLY. WHAT CURRENT FLOWS THROUGH THE LAMP? I = V/R I = 115/66 I = 1.74 AMPS OHM’S LAW
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PRINCIPLES OF ELECTRICITY
INTRODUCTION TERMINOLOGY OHM’S LAW DESCRIPTION SAMPLE PROBLEMS CIRCUITS POWER & ENERGY DIRECT CURRENT ALTERNATING CURRENT A TOASTER CONSTRUCTED OF A 55-OHM RESISTANCE WIRE REQUIRES 4 AMPS FOR ITS OPERATION. WHAT VOLTAGE SHOULD BE APPLIED? V = R X I V= 55 X 4 V = 220 VOLTS OHM’S LAW
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PRINCIPLES OF ELECTRICITY
INTRODUCTION TERMINOLOGY OHM’S LAW CIRCUITS DESCRIPTION OPEN & CLOSED CIRCUITS SHORT CIRCUITS SERIES CIRCUITS PARALLEL CIRCUITS POWER & ENERGY DIRECT CURRENT ALTERNATING CURRENT DESCRIPTION: IN ORDER FOR ELECTRICITY TO FLOW THROUGH A CONDUCTOR UNDER A VOLTAGE DIFFERENCE, IT MUST HAVE A CONTINUOUS PATH FORMING A CLOSED LOOP OR CIRCUIT. CIRCUITS
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PRINCIPLES OF ELECTRICITY
INTRODUCTION TERMINOLOGY OHM’S LAW CIRCUITS DESCRIPTION OPEN & CLOSED CIRCUITS SHORT CIRCUITS SERIES CIRCUITS PARALLEL CIRCUITS POWER & ENERGY DIRECT CURRENT ALTERNATING CURRENT OPEN CIRCUITS: INTERRUPTED CLOSED CIRCUITS: CONTINUITY OF PATH COMPLETE. OPEN & CLOSED CIRCUITS
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PRINCIPLES OF ELECTRICITY
INTRODUCTION TERMINOLOGY OHM’S LAW CIRCUITS DESCRIPTION OPEN & CLOSED CIRCUITS SHORT CIRCUITS SERIES CIRCUITS PARALLEL CIRCUITS POWER & ENERGY DIRECT CURRENT ALTERNATING CURRENT SHORT CIRCUITS: WHEN A CONDUCTING MATERIAL MAKES CONTACT WITH TWO POINTS IN THE LOOP IN SUCH A WAY THAT IT FORM A SHORT CUT AROUND THE LOAD. CURRENT IS INVERSELY PROPORTIONAL TO RESISTANCE, THUS AS RESISTANCE DROPS, CURRENT RISES. SHORT CIRCUITS
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PRINCIPLES OF ELECTRICITY
INTRODUCTION TERMINOLOGY OHM’S LAW CIRCUITS DESCRIPTION OPEN & CLOSED CIRCUITS SHORT CIRCUITS SERIES CIRCUITS PARALLEL CIRCUITS POWER & ENERGY DIRECT CURRENT ALTERNATING CURRENT DESCRIPTION: CURRENT FLOWS IN AN UNDIVIDED, CONSECUTIVE & CONTINUOUS PATH FROM THE SOURCE OF ELECTROMOTIVE FORCE THROUGH THE VARIOUS LOADS & BACK TO THE SOURCE. SERIES CIRCUITS
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PRINCIPLES OF ELECTRICITY
INTRODUCTION TERMINOLOGY OHM’S LAW CIRCUITS DESCRIPTION OPEN & CLOSED CIRCUITS SHORT CIRCUITS SERIES CIRCUITS PARALLEL CIRCUITS POWER & ENERGY DIRECT CURRENT ALTERNATING CURRENT EVALUATION: A SINGLE INTERRUPTION CAN STOP ALL CURRENT FLOW. CURRENT IS THE SAME EVERY WHERE IN THE CIRCUIT. THE VOLTAGE DROP MAY BE DIFFERENT, DEPENDING ON THE VALUE OF EACH RESISTANCE, BUT THE SUM OF THE VOLTAGE DROP MUST ADD UP TO THE VOLTAGE OF THE SOURCE. THE TOTAL RESISTANCE EQUALS THE SUM OF THE INDIVIDUAL RESISTANCES. SERIES CIRCUITS
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PRINCIPLES OF ELECTRICITY
INTRODUCTION TERMINOLOGY OHM’S LAW CIRCUITS DESCRIPTION OPEN & CLOSED CIRCUITS SHORT CIRCUITS SERIES CIRCUITS PARALLEL CIRCUITS POWER & ENERGY DIRECT CURRENT ALTERNATING CURRENT DESCRIPTION: CURRENT IS DIVIDED INTO A NUMBER OF SEPARATE, INDEPENDENT BRANCHES. EVALUATION: IF ONE OF THE LOADS BURNS OUT OR IS DISCONNECTED, THE REMAINDER OF THE CIRCUIT CONTINUES TO FUNCTION. PARALLEL CIRCUITS
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PRINCIPLES OF ELECTRICITY
EVALUATION: THE TOTAL CURRENT FLOWING INTO & OUT OF THE JUNCTION POINTS OF THE BRANCHES EQUALS THE SUM OF THE BRANCH CURRENTS. THE VOLTAGE DROP ACROSS EACH BRANCH OF A PARALLEL CIRCUIT IS EQUAL TO THE VOLTAGE OF THE SOURCE. THE TOTAL RESISTANCE IS EQUAL TO THE RECIPROCAL OF THE SUM OF THE RECIPROCALS OF THE INDIVIDUAL BRANCHES. INTRODUCTION TERMINOLOGY OHM’S LAW CIRCUITS DESCRIPTION OPEN & CLOSED CIRCUITS SHORT CIRCUITS SERIES CIRCUITS PARALLEL CIRCUITS POWER & ENERGY DIRECT CURRENT ALTERNATING CURRENT PARALLEL CIRCUITS
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PRINCIPLES OF ELECTRICITY
INTRODUCTION TERMINOLOGY OHM’S LAW CIRCUITS DESCRIPTION OPEN & CLOSED CIRCUITS SHORT CIRCUITS SERIES CIRCUITS PARALLEL CIRCUITS POWER & ENERGY DIRECT CURRENT ALTERNATING CURRENT CALCULATIONS IN PARALLEL CIRCUITS: THE VOLTAGE IS THE SAME EVERYWHERE IN THE CIRCUIT. THE CURRENT IN EACH BRANCH CAN BE SOLVED USING OHMS LAW: I = V/R. IF THE VOLTAGE IS 120-V AND THE RESISTANCE ON THE BRANCH IS 10-OHMS, THEN I = 120 / 10 OR 12 AMPS. THE TOTAL RESISTANCE = ____________1______________ 1/R /R /R3 PARALLEL CIRCUITS
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PRINCIPLES OF ELECTRICITY
INTRODUCTION TERMINOLOGY OHM’S LAW CIRCUITS DESCRIPTION OPEN & CLOSED CIRCUITS SHORT CIRCUITS SERIES CIRCUITS PARALLEL CIRCUITS POWER & ENERGY DIRECT CURRENT ALTERNATING CURRENT APPLICATION: STANDARD ARRANGEMENT IN ALL BUILDING WIRING.
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PRINCIPLES OF ELECTRICITY
INTRODUCTION TERMINOLOGY OHM’S LAW CIRCUITS POWER & ENERGY DEFINITIONS RELATIONSHIP UNITS DIRECT CURRENT ALTERNATING CURRENT ENERGY: TECHNICAL TERM FOR THE MORE COMMON EXPRESSION WORK. POWER: THE RATE AT WHICH ENERGY IS USED OR THE RATE AT WHICH WORK IS DONE. POWER & ENERGY
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PRINCIPLES OF ELECTRICITY
INTRODUCTION TERMINOLOGY OHM’S LAW CIRCUITS POWER & ENERGY DEFINITIONS RELATIONSHIP UNITS DIRECT CURRENT ALTERNATING CURRENT RELATIONSHIP BETWEEN POWER & ENERGY: THE AMOUNT OF ENERGY USED IS DIRECTLY PROPORTIONAL TO THE POWER OF A SYSTEM AND TO THE LENGTH OF TIME IT IS IN OPERATION. E = P X T POWER & ENERGY
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PRINCIPLES OF ELECTRICITY
INTRODUCTION TERMINOLOGY OHM’S LAW CIRCUITS POWER & ENERGY DEFINITIONS RELATIONSHIP UNITS DIRECT CURRENT ALTERNATING CURRENT POWER: EXPRESSED IN WATTS (W) OR KILOWATTS (KW). ENERGY: WATT-HOURS OR KILOWATT-HOURS. 1 WATT-HOUR EQUALS 1 WATT OF POWER IN USE FOR 1 HOUR. POWER & ENERGY
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PRINCIPLES OF ELECTRICITY
INTRODUCTION TERMINOLOGY OHM’S LAW CIRCUITS POWER & ENERGY DIRECT CURRENT DESCRIPTION SOURCES & GENERATION APPLICATIONS CALCULATIONS ALTERNATING CURRENT ELECTRICITY CONSTITUTES A FORM OF ENERGY THAT OCCURS NATURALLY ONLY IN UNCONTROLLED FORMS: LIGHTNING STATIC ELECTRICITY GALVANIC REACTIONS DESCRIPTION: CURRENT FLOWS ONLY IN ONE DIRECTION, AT A CONSTANT TIME RATE & VOLTAGE.
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PRINCIPLES OF ELECTRICITY
INTRODUCTION TERMINOLOGY OHM’S LAW CIRCUITS POWER & ENERGY DIRECT CURRENT DESCRIPTION SOURCES & GENERATION APPLICATIONS CALCULATIONS ALTERNATING CURRENT SOURCES: BATTERY POWER. SOME SPECIAL TYPES OF GENERATORS PRODUCE DIRECT CURRENT DIRECTLY, BUT THEIR USE IS EXTREMELY LIMITED. RECTIFICATION OF A-C DIRECT CURRENT
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PRINCIPLES OF ELECTRICITY
INTRODUCTION TERMINOLOGY OHM’S LAW CIRCUITS POWER & ENERGY DIRECT CURRENT DESCRIPTION GENERATION APPLICATIONS CALCULATIONS ALTERNATING CURRENT DIRECT CURRENT
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PRINCIPLES OF ELECTRICITY
INTRODUCTION TERMINOLOGY OHM’S LAW CIRCUITS POWER & ENERGY DIRECT CURRENT DESCRIPTION SOURCES & GENERATION APPLICATIONS CALCULATIONS ALTERNATING CURRENT APPLICATIONS: TYPICAL FOR LOW VOLTAGE SITUATIONS. ELEVATOR POWER: GEARLESS TRACTION MACHINES ALWAYS USE A D-C MOTOR. SMALL AMOUNTS OF D-C ARE ALSO USED FOR CONTROLS & TELEPHONES. DIRECT CURRENT
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PRINCIPLES OF ELECTRICITY
INTRODUCTION TERMINOLOGY OHM’S LAW CIRCUITS POWER & ENERGY DIRECT CURRENT DESCRIPTION SOURCES & GENERATION APPLICATIONS CALCULATIONS ALTERNATING CURRENT FORMULA FOR CALCULATING DIRECT CURRENT POWER: P = V X I P = POWER IN WATTS V = VOLTAGE I = CURRENT IN AMPHERES DIRECT CURRENT
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PRINCIPLES OF ELECTRICITY
INTRODUCTION TERMINOLOGY OHM’S LAW CIRCUITS POWER & ENERGY DIRECT CURRENT DESCRIPTION SOURCES & GENERATION APPLICATIONS CALCULATIONS ALTERNATING CURRENT A 12-V BATTERY IS CONNECTED TO A 4-OHM RESISTOR. DETERMINE THE WATTAGE. P = V X I I= V/R = 12-V/4-OHMS = 3 AMPS P = V X I = 12-V x 3-AMPS = 36 WATTS DIRECT CURRENT
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PRINCIPLES OF ELECTRICITY
INTRODUCTION TERMINOLOGY OHM’S LAW CIRCUITS POWER & ENERGY DIRECT CURRENT ALTERNATING CURRENT DESCRIPTION SOURCES & GENERATION APPLICATIONS CALCULATION DESCRIPTION: FLOW OF CURRENT IS PERIODICALLY VARYING IN TIME & IN DIRECTION. ALTERNATING CURRENT
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PRINCIPLES OF ELECTRICITY
INTRODUCTION TERMINOLOGY OHM’S LAW CIRCUITS POWER & ENERGY DIRECT CURRENT ALTERNATING CURRENT DESCRIPTION SOURCES & GENERATION APPLICATIONS CALCULATION CYCLE: THE DISTANCE ALONG THE TIME AXIS SPANNED BY A POSITIVE & A NEGATIVE A-C LOOP. FREQUENCY: THE NUMBER OF CYCLES OCCURRING IN ONE SECOND (US & CANADA- 60 CYCLES/SECOND). UNITS: HERTZ (ONE CYCLE PER SECOND). ALTERNATING CURRENT
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PRINCIPLES OF ELECTRICITY
SOURCE: A-C GENERATOR (ALTERNATOR) WHEN AN ELECTRIC CONDUCTOR IS MOVED IN A MAGNETIC FIELD, A VOLTAGE IS INDUCED IN IT. IF THE CONDUCTOR IS FORMED INTO A COIL & ROTATED IN THE MAGNETIC FIELD, A VOLTAGE OF ALTERNATING POLARITY IS PRODUCED. INTRODUCTION TERMINOLOGY OHM’S LAW CIRCUITS POWER & ENERGY DIRECT CURRENT ALTERNATING CURRENT DESCRIPTION SOURCES & GENERATION APPLICATIONS CALCULATION ALTERNATING CURRENT
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PRINCIPLES OF ELECTRICITY
INTRODUCTION TERMINOLOGY OHM’S LAW CIRCUITS POWER & ENERGY DIRECT CURRENT ALTERNATING CURRENT DESCRIPTION SOURCES & GENERATION APPLICATIONS CALCULATION APPLICATIONS: LIGHTING. ELECTRICAL OUTLETS. MOST MOTORS. ALTERNATING CURRENT
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PRINCIPLES OF ELECTRICITY
INTRODUCTION TERMINOLOGY OHM’S LAW CIRCUITS POWER & ENERGY DIRECT CURRENT ALTERNATING CURRENT DESCRIPTION SOURCES & GENERATION APPLICATIONS CALCULATION DESCRIPTION: THE CURRENT FLOW MAY LEAD OR LAG BEHIND THE VOLTAGE. THIS MEANS THAT THE AMOUNT OF POWER IS NOT AS SIMPLE TO CALCULATE AS IN A D-C CIRCUIT. POWER FACTOR: THE COSINE OF THE ANGLE BETWEEN THE VOLTAGE WAVE AND THE CURRENT WAVE IN A CIRCUIT. IT RANGES FROM 0.0 TO 1.0, ALTHOUGH IT IS USUALLY EXPRESSED AS A PERCENTAGE (0 TO 100%) ALTERNATING CURRENT
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PRINCIPLES OF ELECTRICITY
INTRODUCTION TERMINOLOGY OHM’S LAW CIRCUITS POWER & ENERGY DIRECT CURRENT ALTERNATING CURRENT DESCRIPTION SOURCES & GENERATION APPLICATIONS CALCULATION SINGLE PHASE POWER FORMULA: P = V X I X PF P = POWER, IN WATTS V = POTENTIAL, IN VOLTS I = CURRENT, IN AMPS PF = POWER FACTOR, EXPRESSED AS A DECIMAL FRACTION. ALTERNATING CURRENT
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PRINCIPLES OF ELECTRICITY
INTRODUCTION TERMINOLOGY OHM’S LAW CIRCUITS POWER & ENERGY DIRECT CURRENT ALTERNATING CURRENT DESCRIPTION SOURCES & GENERATION APPLICATIONS CALCULATION IF A LAMP ON A 115-VOLT CIRCUIT DRAWS 5-AMPS AND THE POWER FACTOR IS 0.8, WHAT IS THE WATTAGE? P = V X I X PF P = 115-VOLTS X 5-AMPS X 0.8 P = 460 WATTS ALTERNATING CURRENT
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PRINCIPLES OF ELECTRICITY
INTRODUCTION TERMINOLOGY OHM’S LAW CIRCUITS POWER & ENERGY DIRECT CURRENT ALTERNATING CURRENT DESCRIPTION SOURCES & GENERATION APPLICATIONS CALCULATION ALTERNATING CURRENT
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PRINCIPLES OF ELECTRICITY
INTRODUCTION TERMINOLOGY OHM’S LAW CIRCUITS POWER & ENERGY DIRECT CURRENT ALTERNATING CURRENT DESCRIPTION SOURCES & GENERATION APPLICATIONS CALCULATION THREE PHASE POWER FORMULA: P = V X I X PF X 1.73 P = POWER, IN WATTS V = POTENTIAL, IN VOLTS I = CURRENT, IN AMPS PF = POWER FACTOR, EXPRESSED AS A DECIMAL FRACTION. ALTERNATING CURRENT
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PRINCIPLES OF ELECTRICITY
INTRODUCTION TERMINOLOGY OHM’S LAW CIRCUITS POWER & ENERGY DIRECT CURRENT ALTERNATING CURRENT DESCRIPTION SOURCES & GENERATION APPLICATIONS CALCULATION SAMPLE PROBLEM: A THREE-PHASE MOTOR DRAWS A CURRENT OF 7-AMPS AT 240-VOLTS. THE POWER FACTOR IS 0.8. DETERMINE THE WATTAGE. P = V X I X PF X 1.73 P = 240-VOLTS X 7-AMPS X 0.8 X 1.73 P = 2325 WATTS ALTERNATING CURRENT
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