A meg-ohm test reading of 158 M-Ohms on a motor indicates a failure in the motor windings or winding insulation.

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Multiple Choice

A meg-ohm test reading of 158 M-Ohms on a motor indicates a failure in the motor windings or winding insulation.

Insulation resistance testing with a megohmmeter measures how well the winding insulation blocks leakage current. A high resistance value means the insulation is doing a good job at preventing leakage. A reading of 158 MΩ is generally a healthy insulation level for a motor and does not indicate winding failure; it actually suggests very low leakage. A failure would typically show up as a low resistance value, meaning more leakage, often depending on voltage rating and moisture. When interpreting, consider the motor’s voltage rating and, if possible, check the polarization index (resistance after a longer soak) to confirm long-term insulation quality. In short, this high reading points to good insulation, not a failure.

Insulation resistance testing with a megohmmeter measures how well the winding insulation blocks leakage current. A high resistance value means the insulation is doing a good job at preventing leakage. A reading of 158 MΩ is generally a healthy insulation level for a motor and does not indicate winding failure; it actually suggests very low leakage. A failure would typically show up as a low resistance value, meaning more leakage, often depending on voltage rating and moisture. When interpreting, consider the motor’s voltage rating and, if possible, check the polarization index (resistance after a longer soak) to confirm long-term insulation quality. In short, this high reading points to good insulation, not a failure.

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