Which of these motor maintenance methods do you think is most cost-effective?
Conduct scheduled PMs that include measuring bearing runout, inspecting the windings, testing insulation, realignment, and lubrication.
Save the PMs for only the most expensive motors; replace all others when they fail.
Skip all of the PMs, except for lubrication.
You may be surprised that the last one is the correct answer. However, it's correct only if you install some automated monitoring systems. By skipping PMs that address problems that probably don't exist, you eliminate labor cost while also eliminating the potential for human errors that can cause motor failure. Here's a list of three critical types of monitoring to install:
Temperature. For small, noncritical motors that are easily accessible, you may get by with temperature-indicating stickers and walk-by visual inspections. For others, you want networked monitoring.
Vibration. You don’t need to realign the motor if it’s not out of alignment.
Winding insulation resistance. These systems work for most applications, and they help preserve the insulation integrity during the downtime of the duty cycle.