Motors and Drives

More than half of all electricity in the United States is run through electric motors. A typical large industrial motor consumes its own capital cost's worth of electricity every few weeks—that's a powerful reason for spending a little extra on a more efficient motor.

Most of the scope for energy savings is in industrial motors. Old motors can be replaced by more efficient motors, and the efficiency of any motor can be improved through better controls, use, and maintenance.

- Power Factor
- Voltage Imbalance
- Part-Loading
- Motor Efficiency
- Soft-Start Controls
- Controlling Load Speed and Motor Power with Pulley Diameters
- Electronic Variable Speed Drives
- Repair or Replace
- Replace Failed Motors with Energy Efficient Motors

Voltage imbalance causes large current imbalance

A voltage imbalance of 2.5% can cause a current imbalance of 28%. Voltage imbalance over 1% degrades motor performance, shortens motor life and can void the motor warranty. In addition, motor efficiency drops by about 1% when voltage imbalance is about 2%.



  Unbalanced Voltages (56KB)

Electrical Failure

Over time, winding insulation degrades, usually due to some combination of overheating, aging and over-voltage transients. As winding insulation degrades, the efficiency of the motor may also degrade, causing its operating temperature to increase. Another indication of winding failure is a greater than 10% difference in the amperage drawn by each leg of a three-phase motor. Eventually, winding failure can lead to shock, fire hazard and total motor failure.

Mechanical Failure

Sometimes motor failures are related to mechanical breakdowns, especially for motors in high-vibration environments. 75% of all mechanical failures are due to bearing failure.

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