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Influence of a Voltmeter in a Circuit | Up
Neets Module 16-Introduction to Test Equipment | Next
Figure 3-12.—Simple ohmmeter circuit. |
3-17
Therefore, the sensitivity of a 100-microampere movement is the reciprocal of 0.0001 ampere, or
10,000 ohms per volt.
Q-19. What term is used to express the sensitivity of a voltmeter?
METERS USED FOR MEASURING RESISTANCE
The two instruments you will use most often to check continuity, or to measure the resistance of a
circuit or circuit component, are the OHMMETER and the MEGGER (MEGOHMMETER). The
ohmmeter is widely used to measure resistance and to check the continuity of electrical circuits and
devices. Its range usually extends to only a few megohms. The megger is widely used for measuring
insulation resistance, such as that between a wire and the outer surface of its insulation, and the insulation
resistance of cables and insulators. The range of a megger can be extended to more than 1,000 megohms.
Q-20. What instrument is used for measuring the insulation resistance of cables?
The Ohmmeter
A simple ohmmeter circuit is shown in figure 3-12. The ohmmeter consists of the dc milliammeter,
discussed earlier in this chapter, and the added features shown below:
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