I’m sure many of you have heard the riddle “How do you eat an elephant?” The answer, of course is “One bite at a time”. The same holds true for starting a motor testing program. Such a task can seem monumental at the outset, much like eating the elephant, but breaking it down into manageable pieces gives you a place to start, making the overall task easier to envision. In a facility that has a thousand motors in operation, starting a motor testing program is no small task, no matter how you approach it. So, let’s break it down.
If you’ve priced out motor testing equipment recently, you were probably surprised by how expensive the technology is relative to other PdM tools. Top of the line testers, those capable of performing both Energized and De-energized testing protocols in a single unit, can cost upwards of $25,000. That’s a chunk of change and an expenditure that will not be taken lightly by any company. But these aren’t the only options. Also available on the market are lower-cost units that perform fewer functions. “Crawling before you walk” is another cliché that applies here. You can spend a couple thousand dollars for an instrument that gives limited testing capability, but is a great starting point for your budding motor test program.
A great place to begin is where you receive your motors. Starting here works well because it’s easy to set-up and put in place. As motors are received, either new or from a motor shop where they have been serviced, a simple electrical test can be performed before the motor is placed into inventory. It’s important on the front-end of this process to determine acceptance criteria. Two easily tested parameters are resistive and impedance imbalance. Imbalances in either of these electrical characteristics in a new or rewound motor can show defects that are small enough to allow a motor to enter service, but sufficient in magnitude to shorten overall service life.
Acceptance testing is valuable because it can serve more than one purpose. The obvious primary benefit is to catch substandard motors and prevent them from being put into service. The secondary benefit is that it’s an easy first bite of the elephant. With a small investment towards equipment and established acceptance criteria, you can be ready to go.
Once you’re able to show some return for these first small steps, the buy-in for another “bite of elephant” will be much easier to achieve!