puckman, I am also an electrician. I work in a steel foundry with just about every type of motor you could encounter. I didn't see your last page, but to answer your question about a certain size hp you would start with PM's. For the most part, we don't do alot with small 3 phase squirrel cage motore under 3 hp. A typical off the shelf price could be 150-200 dollars. However, I guess it could depend on the type of motor, and the importance of it to the machinery or downtime problems. No matter how small, a motor with brushes should get checked periodically for obvious reasons. Greasing of the bearings is also something you could do. How often depends on the type of bearings in the motor. Some say to never grease because it is a sealed bearing, but rather to change the bearing every 20,000 hrs.It depends on the manufactuter. How about using a megger? This is a good measure of showing that the insulation is breaking down on the windings. We only megger 100 HP motors and up typically. Although we should do smaller ones. Motor's with brakes, need PM'd, no matter the size. That brake is ther for a reason.
