The plant air system periodically “goes down” (can’t maintain pressure) because one of the compressor motors fails. While the electricians are good at replacing the failed motors, the plant engineer wants you to solve the high rate of failures and thus reduce costly production interruptions.
He’s already checked the loading cycles, dryers, accumulators, and other items/issues that fall strictly under the compressor system itself. He’s even hired a contractor to use ultrasonics to find and fix leaks. He says all this work should eliminate from consideration that the compressor motors are just overworked.
What can you do to eliminate causes from your electrical perspective?
Start by checking the ventilation in the compressor room; louvers, fans, and filters are all failure points. Then, install temperature monitoring in the room and vibration sensors on the motors.
Next, look at the power supply. Compressor rooms are typically located along the perimeter because of noise. This means longer runs so check for voltage drop. Do you have all three phases and are their voltages in balance? If you have more than 2% voltage imbalance, bring it down. Conduct a power quality analysis; low power factor, excess third harmonics, and other issues can cause motor overheating.
Grounding in place of bonding means undesired current will flow through motor bearings. Thus, ensure you have a low-impedance equipment grounding conductor (EGC) [NEC Sec. 250.118], remembering it’s really an equipment bonding conductor. Ground rods at the motors do nothing.
