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Electric Motors


Overload Relays for Motor Protection

Improve system reliability and efficiency BY KEVIN TRIMMER, Eaton Corporation Nearly a third of global energy demand is attributable to manufacturing. Overall, the industry’s use of energy has grown by 61 percent between 1971 and 2004. According to the International Energy Agency (IEA) analysis,...

Bearing Protection of Inverter-duty Motors

Although it is now common knowledge that inverters—also known as variable frequency drives—often induce unwanted motor shaft voltages, many customers who purchase three-phase alternating current (AC) induction motors do not realize that models labeled “inverter-duty” or “inverter-ready”...

Maximizing Electric Motor Efficiency

How to get the most from your rotating machines BY STEPHEN MANSFIELD, TechnoWise Inc. An area of great interest is improving the efficiency of electrical devices. More electric motor efficiency means less electrical energy consumed and thus less impact to the environment. By far, the largest...

Understanding Short Circuit Motor Contribution

A back to basics approach BY DARRELL BROUSSARD, GE Industrial Solutions An electric motor’s contribution is the current generated by a motor or motors during a short circuit condition. It represents a small but important value that is needed to determine the maximum short circuit current...

Variable Frequency Drive Cable Best Practices

Correcting common mistakes that affect performance and safety BY PETER COX, Belden, Inc. Most industrial operations today are looking for ways to reduce costs in these tough economic times. Variable-frequency drives (VFDs) are popular in many applications because they provide energy savings and a...

Enhance Performance with VFD Technology

Energy savings for pumping applications BY TOM NEUBERGER & STEVEN WESTON, Eaton In the early days of variable frequency drive (VFD) technology, the typical application was in process control for manufacturing synthetic fiber, steel bars and aluminum foil. Because VFD improved process...

Motors & Drives

Overload Protection for Electric Motors

Thermal images are an easy way to identify apparent temperature differences in industrial three-phase electrical circuits, compared to their normal operating conditions. By inspecting the thermal differences of all three phases side-by-side, technicians can quickly spot performance anomalies on individual legs due to unbalance or overloading.

Electrical unbalance is generally caused by differing phase loads but may also be due to equipment issues such as high resistance connections. A relatively small unbalance of the voltage...

Motors & Drives Articles