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Electric Motors


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”...

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...

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...

Reviewing Electric Motor Reliability Research

What did the studies really say—then and now? BY HOWARD PENROSE, Ph.D., CMRP One of the most frequently quoted studies related to electric motor reliability is a 1983 Electric Power Research Institute (EPRI) project, entitled “Assessment of the Reliability of Motors in Utility Applications:...

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,...

Improving Motor Maintenance Practices

Useful approaches to building an effective operation and maintenance program BY IAN CULBERT AND VICKI WARREN, Iris Power Engineering The pressures to be more competitive and cost-effective in today’s deregulated market have driven plants to reduce resources by making more informed,...

Motors & Drives

Monitoring Stator Winding Deterioration

The importance of partial discharge testing in electric motors

BY VICKI WARREN, Iris Power LLP

Comparing partial discharge (PD) results obtained from a single machine is a valuable tool that enables companies to observe the gradual deterioration of a machine stator winding. Proper monitoring of stator winding deterioration allows companies to plan appropriate maintenance for the machine in accordance to International Electrotechnical Commission’s IEC 60034 standard: “Rotating Electrical Machines - Part 27-2: Online Partial Discharge...

Motors & Drives Articles