418 Chapter Review SUMMARY ■ Safety fi rst! Always follow all safety procedures and use appropriate PPE before and while performing electrical testing. ■ Check the settings on test equipment before con- necting to ensure it can handle the voltages and transients present. ■ Always de-energize a circuit before testing for resistance. ■ A receptacle tester indicates if a receptacle has been properly wired and grounded. ■ A digital multimeter (DMM) is one of the most versatile tools in the electrical technician’s toolbox. Modes, inputs, safety features, and any advanced functions will vary based on your device. ■ Always discharge a capacitor before testing. ■ Connect a DMM in series with the source and the load when making current measurements. ■ Clamp-on ammeters allow you to measure current without needing to disconnect conductors. ■ A megohmmeter uses high voltage to make insula- tion resistance measurements. ■ An oscilloscope shows voltage on the Y axis and time on the X axis. ■ Triggering on an oscilloscope provides a way to lock the waveform in a stationary position on the scope screen so that waveforms may be observed and measured. ■ Th e oscilloscope calibrator output allows you to verify proper operation of an oscilloscope and set the probe compensation of multiplier probes. ■ An arbitrary function generator (AFG) can be used to produce various types of signals when bench test- ing an assembly. ■ A phase sequence tester verifi es that the phase con- ductors in a three-phase circuit are in the proper order. If the tester shows the phases to be reversed, switch the position of any two conductors. If a motor runs backward, switch the position of any two of the three motor leads. ■ IR thermometers measure the infrared radiation being emitted from an object. ■ Electrical testing equipment must be calibrated periodically to ensure accurate measurements. REVIEW QUESTIONS Answer the following questions using the information provided in this chapter. 1. True or False? Electrical equipment should be energized before testing. 2. Undesirable voltage spikes in excess of the intended voltage are known as _____ or _____. 3. What are the two main types of troubleshooting? 4. What does a receptacle tester tell a technician? 5. What is the modern version of the screwdriver voltage tester or receptacle tester and how does it operate? 6. If you want to measure the resistance of a circuit, what test instrument would you likely use? What would your fi rst step be before taking the measurement? 7. List fi ve measurements that a typical DMM can make. 8. What does the diode test mode of a test instrument measure? 9. True or False? Capacitors are generally specifi ed in either μF or pF, but a DMM may display the reading in a diff erent unit. 10. Convert 5800 nF to microfarads. 11. What test instrument replaces continuity testers with a continuity test mode? What does the continuity test measure, and how does it let the technician know the circuit has continuity? 12. Most advanced multimeters measure the amount of AC voltage that would produce the same amount of power that a DC voltage would. Th is is designated _____ on multimeters. 13. What is a phantom voltage? Copyright Goodheart-Willcox Co., Inc.