TABLE OF CONTENTS Refer to Figure B-8 for this section.
Item 1 in the figure is the electric motor. The most common inspection item for the motor is for heat. The motor should be approximately 25 to 29 F higher in temperature than the surrounding environment. If the motor's temperature is higher than this, it will have a shorter life due to the deteriorating effect the heat has on the insulation of the motor. Every 20 -temperature rise above the environmental temperature cuts the life of the insulation by one half. When the insulation fails, so does the motor. If the temperature rises above this level, efforts should be made to find the problem, so the motor can be cooled back down again.
Another inspection point on the motor is the bearings, which support the rotating part of the motor (usually called the armature or the rotor). The inspection of the bearings should include three basic items: heat, noise, and vibration. These three indicators of trouble may appear singly or in any combination. Monitoring these three conditions may require nothing more than the use of the inspector's natural senses. If the equipment is critical in the manufacturing process, it may be advisable to use some form of monitoring or nondestructive testing equipment. For monitoring the temperature, some form of hand-held thermometer may be sufficient. If the equipment is in a difficult-to-reach or unsafe area, some form of temperaturemonitoring device may...
