Delmar\'s STE Chapter on Meters

8. Unit 9 Measuring Instruments A shunt is used to set the value of the ammeter.

9. Unit 9 Measuring Instruments Many electricians use the clamp-on type of AC ammeter. Please note the clamp-on ammeter reads only one conductor at a time.

12. Unit 9 Measuring Instruments Digital Ohmmeter

13. Unit 9 Measuring Instruments Digital Voltmeter

14. Unit 9 Measuring Instruments Low-impedance Voltage Tester The low-impedance voltage tester has a very large current draw compared to other types of voltmeters and should never be used to test low-power circuits.

15. Unit 9 Measuring Instruments Low-impedance Voltage Tester This tester has an impedance of 5000 Ω and can generally be used to measure voltages as high as 600 V.

16. Unit 9 Measuring Instruments Low-impedance Voltage Tester This is also known as a solenoid type tester. This tester is not susceptible to giving the misleading voltage readings caused by high-impedance ground paths or feedback voltages.

17. Unit 9 Measuring Instruments Low-impedance Voltage Tester High-impedance ground paths can produce misleading voltage readings.

18. Unit 9 Measuring Instruments Low-impedance Voltage Tester

19. Unit 9 Measuring Instruments Reading a Digital Meter Many digital meters are auto-ranging, which means that they select the range scale automatically. This type will display a notation beside the numerical digits to indicate the meter scale.

22. Unit 9 Measuring Instruments Review: 7. Ohmmeters are used to measure the resistance in a circuit. 8. There are two basic types of Ohmmeters: analog and digital. 9. Ohmmeters must never be connected to a circuit that has power applied to it.

23. Unit 9 Measuring Instruments Review: 10. Digital multimeters display their value in digits instead of using a meter movement. 11. Digital ohmmeters measure resistance by measuring the voltage drop across an unknown resistor when a known amount of current flows through it.

24. Unit 9 Measuring Instruments Review: 12. Low-impedance voltage testers (solenoid type) are not susceptible to indicating a negligible voltage caused by a high-impedance ground or feedback.