Suppose it is desired to determine the...

Question 1 of 270705eccefa4bacbc34ba4d4842c

Suppose it is desired to determine the integrity of the insulation of a 4160 VAC motor. What type of insulation resistance tester (megger) would be suitable?

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Question 1 of 27070

Suppose it is desired to determine the integrity of the insulation of a 4160 VAC motor. What type of insulation resistance tester (megger) would be suitable?

🔍 Key Concepts

• Insulation resistance testing guidelines for medium-voltage equipment (in kV range) • Relationship between rated line voltage of the motor and the DC test voltage of the megger • Why higher-than-rated test voltage is used, and what risk an excessively high test voltage might pose

💭 Think About

• First, convert the motor’s rated voltage from volts to kilovolts and think about the general rule of thumb for what DC test voltage is used on equipment in that kV range. • Compare each megger rating to the motor’s 4160 VAC rating: which options clearly seem too low to meaningfully stress the insulation, and which might be unnecessarily high? • Ask yourself: For typical shipboard/industrial practice, what approximate megger voltage range is normally paired with 4 kV-class motors?

✅ Before You Answer

• Verify the standard practice tables (such as IEEE or manufacturer guidelines) that suggest test voltages for 1–5 kV class equipment. • Check that the selected megger voltage is higher than the motor’s phase-to-ground voltage yet still within common recommended test limits. • Eliminate any options that would be obviously inadequate to reveal insulation weakness or so high that they could risk damaging otherwise good insulation.