What is a common failure mode of electric motors?

Inadequate insulation is recognized as a common failure mode of electric motors due to the vital role insulation plays in protecting the motor's windings from electrical and thermal stress. Insulation is essential for preventing short circuits that can result from moisture, dirt, or mechanical damage. Over time, factors such as heat buildup, voltage fluctuations, and environmental conditions can degrade the insulating materials, leading to loss of performance and potential failure of the motor. Consequently, ensuring adequate insulation is critical for the longevity and reliable operation of electric motors.

The other options are less relevant as common failure modes. Excessive lubrication, for instance, can lead to problems such as bearing failure or excessive heat generation, but it is not as fundamental a failure mechanism as insulation issues. High thermal conductivity is not a typical failure mode in itself, rather it is a property of materials that affects heat dissipation, but it doesn't directly cause motor failure. Similarly, too much cooling is generally not a condition that leads to motor failure; instead, it's usually beneficial. Understanding the importance of proper insulation helps in implementing preventive maintenance strategies to avoid motor failures.