2019 Cengage CHAPTER 3 ELECTRIC CIRCUITS INTRODUCTION Electrical
- Slides: 17
© 2019 Cengage
CHAPTER 3 ELECTRIC CIRCUITS INTRODUCTION • Electrical systems are composed of various types of circuits • A parallel circuit has more than one path through which electricity flows • A series circuit has only one path through which electricity flows • A series-parallel circuit is a combination of series and parallel circuits © 2019 Cengage
CHAPTER 3 ELECTRIC CIRCUITS Basic Concepts of Electric Circuits • Electric circuit • Complete path of an electric current and any necessary elements • Power source and load • Closed circuit • Circuit is complete • Current can flow © 2019 Cengage
CHAPTER 3 ELECTRIC CIRCUITS Basic Concepts of Electric Circuits • Open circuit • Also called a broken circuit • Path of current flow is interrupted • Electric circuit requirements • Complete path for electrons to flow through • Source of electrons © 2019 Cengage
CHAPTER 3 ELECTRIC CIRCUITS Series Circuits • Overview • Simplest and easiest electric circuit to understand • Allows only one path of current flow • Examples • Switches • Controls © 2019 Cengage
CHAPTER 3 ELECTRIC CIRCUITS Series Circuits • Applications • Series circuits are used in most control circuits • Examples • Heating equipment • Cooling equipment • Refrigeration equipment © 2019 Cengage
CHAPTER 3 ELECTRIC CIRCUITS Series Circuits • Characteristics and calculations • Current draw • Only one path for the current flow • I t = I 1 = I 2 = I 3 = I 4· · · • Resistance • Total resistance is the sum of all the resistances in the circuit • Rt = R 1 + R 2 + R 3 + R 4 + · · · © 2019 Cengage
CHAPTER 3 ELECTRIC CIRCUITS Series Circuits • Characteristics and calculations • Voltage • Completely used by all the loads • Voltage drop • Amount used or lost through any load or conductor when moving current through that part of the circuit • Et = E 1 + E 2 + E 3 + E 4 + · · · © 2019 Cengage
CHAPTER 3 ELECTRIC CIRCUITS Parallel Circuits • Overview • More than one path for electrons to flow • Each device is connected to both supply voltage conductors • Common in industry • Most loads operate from line voltage • Voltage supplied to equipment from main power source © 2019 Cengage
CHAPTER 3 ELECTRIC CIRCUITS Parallel Circuits • Applications • Power circuits are several parallel circuits used together • Supply the correct line voltage • Heating systems • Cooling systems • Refrigeration systems © 2019 Cengage
CHAPTER 3 ELECTRIC CIRCUITS Parallel Circuits • Characteristics of parallel circuit and calculations • Current draw • Determined for each part of the circuit • Depends on resistance of that portion • Total current draw • Sum of currents in individual sections • Total ampere draw: It = I 1 + I 2 + I 3 + I 4 + · · · Cont. © 2019 Cengage
CHAPTER 3 ELECTRIC CIRCUITS Parallel Circuits • Characteristics of parallel circuit and calculations • Resistance • Gets smaller as more resistances are added • Two resistors: Rt = (R 1 x R 2)/(R 1 + R 2) • More than two: 1/Rt = 1/R 1 + 1/R 2 + 1/R 3 + 1/R 4 + · · · © 2019 Cengage
CHAPTER 3 ELECTRIC CIRCUITS Parallel Circuits • Characteristics of parallel circuit and calculations • Voltage drop • Line voltage being supplied to the load • Each load uses the total voltage being supplied to the load • Equation for voltage applied to each of four components: Et = E 1 = E 2 = E 3 = E 4 © 2019 Cengage
CHAPTER 3 ELECTRIC CIRCUITS Series-Parallel Circuits • Overview • Combination circuit made of series and parallel circuits • Used sparingly • More often seen on full wiring layouts • Used to combine control circuits with circuits that supply power to loads © 2019 Cengage
CHAPTER 3 ELECTRIC CIRCUITS Series-Parallel Circuits • Application • Used in most types of heating, cooling, and refrigeration equipment • Allows required voltage to be supplied to electrical loads in the system • Both series and parallel circuits are used to supply electrical power to loads © 2019 Cengage
CHAPTER 3 ELECTRIC CIRCUITS SUMMARY • The three types of circuits used in the industry are series, parallel, and series-parallel • The series circuit is used for most control circuits used in the industry • Parallel circuits are used in equipment to ensure that proper voltage is supplied • The series parallel circuit is a combination of series and parallel circuits © 2019 Cengage
CHAPTER 3 ELECTRIC CIRCUITS SUMMARY • The series and parallel circuits have different relationships of voltage, amperage, and resistance © 2019 Cengage