Chapter 7 Series-Parallel Circuits

1. Chapter 7Series-Parallel Circuits AUT 242 – Automotive Electric II

2. OBJECTIVES After studying Chapter 7, the reader will be able to: • Prepare for ASE Electrical/Electronic Systems (A6) certification test content area “A” (General Electrical/Electronic System Diagnosis). • Identify a series-parallel circuit. • Calculate current flow and voltage drops in a series-parallel circuit. • Identify where faults in a series-parallel circuit can be detected or determined.

3. Combination circuit Compound circuit Series-parallel circuits KEY TERMS

4. SERIES-PARALLEL CIRCUITSDEFINITION • Series-parallel circuits are a combination of series and parallel segments in one complex circuit. • A series-parallel circuit is also called a compound or combination circuit. • Many automotive circuits include sections that are in parallel and in series.

5. SERIES-PARALLEL CIRCUITSTYPES OF SERIES-PARALLEL CIRCUITS • A series-parallel circuit includes both parallel loads or resistances, plus additional loads or resistances that are electrically connected in series. • There are two basic types of series-parallel circuits. • A circuit where the load is in series with other loads is parallel. • A circuit where either a parallel circuit contains resistors or loads are in series in one or more branches.

6. SERIES-PARALLEL CIRCUITSTYPES OF SERIES-PARALLEL CIRCUITS • This complete headlight circuit with all bulbs and switches is a series-parallel circuit.

7. SERIES-PARALLEL CIRCUITSSERIES-PARALLEL CIRCUIT FAULTS • If a conventional parallel circuit, such as a taillight circuit, had an electrical fault that increased the resistance in one branch of the circuit, then the amount of current flow through that one branch will be reduced. • The added resistance, due to corrosion or other similar cause, would create a voltage drop. • As a result of this drop in voltage, a lower voltage would be applied and the bulb in the taillight would be dimmer than normal because the brightness of the bulb depends on the voltage and current applied.

8. SOLVING SERIES-PARALLEL CIRCUIT CALCULATION PROBLEMS • The key to solving series-parallel circuit problems is to combine or simplify as much as possible.

9. SERIES-PARALLEL CIRCUIT CALCULATION EXAMPLES 2

10. SERIES-PARALLEL CIRCUIT CALCULATION EXAMPLES 12

11. SERIES-PARALLEL CIRCUIT CALCULATION EXAMPLES 2 2

12. SERIES-PARALLEL CIRCUIT CALCULATION EXAMPLES 1

13. SUMMARY • A series-parallel circuit is called a compound circuit or a combination circuit. • A series-parallel circuit is a combination of a series and a parallel circuit. • A fault in a series portion of a series-parallel circuit would affect the entire circuit operation if the series part was in the power or the ground side of the parallel portion of the circuit. • A fault in one leg of a series-parallel circuit will affect just the component(s) in that one leg.

14. REVIEW QUESTIONS • Explain why an increase in resistance in the series part of a series-parallel circuit will affect the current (amperes) through the parallel legs (branches). • What would be the effect of an open circuit in one leg of a parallel portion of a series-parallel circuit? • What would be the effect of an open circuit in a series portion of a series-parallel circuit?

15. CHAPTER QUIZ 1. Half of the dash is dark. Technician A says that a defective dash light dimmer can be the cause because it is in series with the bulbs that are in parallel. Technician B says that one or more bulbs could be defective. Which technician is correct? • Technician A only • Technician B only • Both Technicians A and B • Neither Technician A nor B

16. CHAPTER QUIZ 2. All brake lights are dimmer than normal. Technician A says that bad bulbs could be the cause. Technician B says that high resistance in the brake switch could be the cause. Which technician is correct? • Technician A only • Technician B only • Both Technicians A and B • Neither Technician A nor B

17. CHAPTER QUIZ 3. Solve for total resistance (RT) and total current (IT). • 10 ohms and 1.2 A • 4 ohms and 3 A • 6 ohms and 2 A • 2 ohms and 6 A

18. CHAPTER QUIZ 4. Solve for the value of R 3 and total resistance (RT). • 12 ohms and 12 ohms • 1 ohm and 7 ohms • 2 ohms and 8 ohms • 6 ohms and 6 ohms

19. CHAPTER QUIZ 5. Solve for voltage (E) and total resistance (RT). • 16.3 volts and 12 ohms • 3.3 volts and 2.4 ohms • 1.36 volts and 1 ohm • 6 volts and 4.4 ohms

20. CHAPTER QUIZ 6. Solve for R 1 and total resistance (RT). • 3 ohms and 15 ohms • 1 ohm and 15 ohms • 2 ohms and 5 ohms • 5 ohms and 5 ohms

21. FIGURE 7–12 Chapter Quiz question 7. CHAPTER QUIZ 7. Solve for total resistance (RT) and total current (I). • 3.1 ohms and 7.7 amperes • 5.1 ohms and 4.7 amperes • 20 ohms and 1.2 amperes • 6 ohms and 4 amperes

22. CHAPTER QUIZ 8. Solve for the value of E and total resistance (RT). • 13.2 volts and 40 ohms • 11.2 volts and 34 ohms • 8 volts and 24.2 ohms • 8.6 volts and 26 ohms

23. CHAPTER QUIZ 9. Solve for total resistance (RT) and total current (I). • 1.5 ohms and 8 amperes • 18 ohms and 0.66 ampere • 6 ohms and 2 amperes • 5.5 ohms and 2.2 amperes

24. CHAPTER QUIZ 10 Solve for total resistance (RT) and total current (I). • 48 ohms and 0.42 ampere • 20 ohms and 1 ampere • 30 ohms and 0.66 ampere • 10.2 ohms and 1.96 amperes