Question 35Electricity/Electronics - 1st Asst/Chief70% to pass
To prevent shaft currents in an alternator, the outboard bearing shell or outboard bearing pedestal is insulated. If the methodology used is the insulated bearing pedestal, how is the pedestal insulation evaluated?
AI Explanation
The correct answer is D) Measuring the resistance between the bearing pedestal and the bearing bedplate of a disassembled machine with a 500-Volt megohmmeter.
The reason this is the correct answer is that to properly evaluate the insulation of the bearing pedestal, a high-voltage megohmmeter (typically 500 Volts) should be used on the disassembled components. This allows for a more accurate assessment of the insulation resistance, as a digital multimeter may not provide a sufficiently high voltage to properly test the insulation. Additionally, evaluating the disassembled components ensures that the measurement is not influenced by any other connected parts or wiring.
The other options are incorrect because they either use an improper measurement method (option A and C using a digital multimeter) or do not specify that the machine should be disassembled (option B).
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