From ALL-TEST PRO
If you run variable frequency drives (VFDs) on plant components, you may relate to a paint production facility’s recent emergency. Easy Tool, a condition monitoring solutions provider in Italy, works with a paint production facility in Ancona, a city along Italy’s Adriatic coast. This paint producer has worked with Easy Tool since 2013, relying on their field engineers to perform regular monitoring services for the motors, fans, pumps and mixers operating in the facility.
Every six months, field engineers from Easy Tool spend six days at the facility, using a variety of technologies to test things out, perform vibration analysis and the like. In January, Field Engineer Ettore Di Pasquale was performing a dynamic test on a 55-kilowatt, 4-pole motor at the facility when he discovered a significant current imbalance.
The motor was driving a fan that sucks solvents from the air. It’s critical for ensuring worker safety. If the fan stops running, the paint producer must stop the production process. The fan is comprised of an impeller keyed directly to the motor shaft, which is controlled by a VFD. Di Pasquale used the ALL-TEST PRO On-Line II™ energized motor testing instrument to test the fan motor and discovered the current imbalance at the VFD input and output.
“Testing showed a current imbalance of 12.4 percent at the input of the VFD that became 74.8 percent at the output of the VFD,” Di Pasquale explained. “This is not good for the motor—the VFD should supply the fan motor with balanced current. Given such high levels of current imbalance and the absence of several input half-waves, it became clear to me that the motor and fan were fine, but that the VFD needed to be replaced.”
Of course Di Pasquale discussed the issue with the facility owner. Trusting Di Pasquale’s recommendation, the producer had the VFD removed and confirmed there had been serious damage to the VFD’s internal diodes. After a new VFD was installed, Di Pasquale went back to test the fan motor. The second round of energized motor testing with the ATPOL II™ showed healthy waveforms.
Whether a VFD is in the mechanic’s shop or on a slat conveyor, it needs to be checked regularly. There are easy-to-use, portable instruments domestically and internationally, that can help you check the condition of your motors. When you know what is really happening with your equipment, you can make smart decisions to keep people safe and to keep your operation running smoothly.
For more information, visit www.alltestpro.com. Let them know you saw it in AsphaltPro Magazine.