If a digital multimeter is set up as shown in figure "A" of the illustration to test an AC contactor coil, what would the display read if the coil is open-circuited? Illustration EL-0214
• Ohms (Ω) setting on a digital multimeter and what it measures • Behavior of a meter when there is an open circuit versus a normal resistance • Difference between resistance readings and voltage readings on the same meter
• Look closely at how the meter selector is set in figure A—what quantity is actually being measured? • If a coil is open-circuited, is there a complete path for current? How does a digital ohmmeter indicate that condition on its display? • Which of the answer choices looks like a normal coil resistance, and which choices indicate either a short circuit or no continuity at all?
• Verify that the meter in figure A is on the ohms (Ω) range, not a volts range • Recall what most digital meters display when the resistance is too high or infinite (no continuity) • Eliminate any choices that represent voltage instead of resistance, since the circuit is not energized in an ohms test
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