Most utilities maintain these motors through time-based preventative maintenance (PM) programs. Examples include motors ranging from 480-13,800 V used to operate compressors, pumps and fans.

Some plants can have as many as 20-30 critical motors, with five to ten on average.Ĭritical motors are those that could significantly impair the ability to safely meet business objectives or affect production levels if they unexpectedly go offline. No matter the industry, manufacturing and processing plants rely heavily on motors, though the number and type vary depending on the size of the plant and type of fuel burned. By doing so, they can save utilities hundreds of thousands of dollars in repair fees for expensive rewinding, failure-to-produce penalties and lost production time.įurthermore, permanently installed automatic testing devices allow for “hands-off” monitoring without having to access cabinets-keeping technicians out of harm’s way. With so much at risk, plant managers are recognizing the value of continuous megohm monitoring of insulation resistance that initiates the moment the motor is off until it is re-started.Īrmed with this real-time information, maintenance personnel can take corrective actions ahead of time to avoid a failure that would interrupt production. In the United States, non-fatal arc flash incidents occur approximately five to ten times per day, with fatalities at the rate of approximately one per day. These tests expose technicians to potential arc flashes when they access the cabinet. Portable megohmmeters also require electrical technicians to manually disconnect the equipment cables and connect the test leads on potentially energized or damaged equipment to perform the manual testing. The value of continuous megohm monitoring of insulation resistance lies in its ability to measure resistance the moment the motor is off until it is re-started again. In a matter of days, motor windings and cables exposed to moisture, chemicals, contaminants or vibration can be compromised and fail at startup.

However, these tests only provide a “snapshot” of motor health. For decades, plant personnel have performed insulation resistance tests with handheld megohmmeters to prevent motor failures that lead to costly unplanned shutdowns, failure-to-produce penalties and rewinding repairs.

Motor winding insulation