S U M M A R Y Troubleshooting and repairing motor control and circuit protection devices are routine activities for the HVAC technician. This chapter described the power transmission system and the various types of transformers used to reduce voltage to usable levels in residential and commercial instal- lations. Also described were the different types of circuit protection devices and their operation. Finally, the importance of making good terminal connections and types of connectors was discussed. Skills acquired in these areas will improve your ability to diagnose and correct system problems. T E S T Y O U R K N O W L E D G E Answer the following questions using the information provided in this chapter. 1. True or false? Single-phase power can be obtained from a three-phase system. 2. Most residential units have two hot wires and a neutral wire. What is the supplied voltage? How many phases are supplied? 3. An advantage of alternating current is that it can be _____ at one voltage, transmitted at _____ voltage, and reduced to a lower voltage at the _____. 4. What is the operating principle for a transformer? 5. Does a step-up transformer increase or decrease voltage? 6. Ampacity is the amount of _____ a wire can safely carry. 7. Name the two devices that protect circuits against overcurrent. 8. True or false? A dual-element fuse should be used in circuits serving electric motors. 9. What two ratings determine the physical size of a cartridge fuse? 10. A GFCI protects people against a _____ fault. 484 Heating and Cooling Essentials Copyright Goodheart-Willcox Co., Inc.