The plant engineer asked you to walk out to the small MCC near the plant’s paper making machine. There, he pointed to an open cubicle with a floor fan blowing into it.
“That’s the motor starter for the main drive motor under the machine. The operators put that fan there to keep the overloads from blowing. I want you to put a lock on that door and figure out why the overloads blow.”
Where do you start?
After you put a lock on that door, you need to find out why the motor is drawing enough additional current to open the heater strips. The application (paper, which means particulates) and location (under the machine) are two big clues.
If it’s an open drip proof (OPP) case motor, replacing it with the correct Totally Enclosed Fan Cooled (TEFC) motor may solve the problem. But is there a washdown procedure with this machine? If so, specify a Totally Enclosed Washdown (TEW) motor.
If the motor is already a TEFC or TEW, maybe accumulated paper is insulating it (a hotter motor draws more current). Or maybe particles accumulating in the machine have increased the effective load; the plant engineer needs to investigate that issue.
