Last year, the plant added a production line to accommodate a particular customer. It’s been nothing but trouble ever since. The line includes a 50 HP drive motor and several smaller motors, six extrusion system heaters, a dye mixer/feeder system, a baking/drying section, and cooling fans. The biggest headache is the frequent need to replace motors. Nobody can figure out why the failure rate is so high. A consultant “solved” the “motor overheating problem” with a forced air ducting system, but the motors still fail.
What’s your next step?
Are the heaters on their own transformer? If not, one open heater element may cause enough voltage imbalance to explain the high failure rates. The consultant believed heat was the cause; perhaps he was looking at evidence of motor overheating, a problem caused by voltage imbalance.
Are the heaters all the same size? If they are different sizes and allocated among the phases as if they are the same size, you will also get voltage imbalance. Are they allocated by actual load? Is any heater open?
Revisit motor selection; a mistake here could explain everything. Use a power analyzer to look at power factor, etc.
