Question 448Electricity & Electronics - QMED

70% to pass

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

Diagram for USCG Electrical QMED: If a digital multimeter is set up as shown in figure "A" of the illustration to...
A0.03 ohms
B22 ohms
COL ohms
D110 V
AI Explanation

The correct answer is C) OL ohms. When a digital multimeter is set up to measure resistance (ohms) and the circuit being tested is open-circuited, the multimeter will display "OL" (overload) to indicate that the resistance is out of the measurable range. This is because an open circuit has infinite resistance, which the multimeter cannot accurately measure. The other options are incorrect because: A) 0.03 ohms would be an extremely low resistance, which is not typical for an open-circuited AC contactor coil. B) 22 ohms would be a reasonable resistance for a functioning AC contactor coil, but not for an open-circuited one. D) 110 V is the voltage of the AC power source, not the resistance measurement.

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Official Resources
46 CFR Electrical Engineering 46 CFR Machinery & Electrical USCG National Maritime Center
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