Gaps in Your Motor Reliability Program, Part 2

July 1st, 2016

Part 1 of this two-part series covered the first part of PdMA Corporation vice president of development Noah Bethel's presentation at Reliable Asset World II in Clearwater Beach, Florida, in June 2015. Bethel's main point was that data collection on a motor reliability program is meaningless without the proper insights and analysis. In Part 1 Bethel examined the basics of an electric motor reliability program, how to understand electric motor fault zones, and the importance of quality control. Part 2 will cover trending, troubleshooting and management in a changing industry.

Trending refers to data collection on motors performed on a regular and consistent basis. Its purpose is to identify potential problems and develop a detailed history of any issues uncovered by the data. It is during the latter when the reliability gap most often occurs. Data is rarely analyzed because those who record it are not trained to analyze it. The result is a data shortcoming – statistics are collected, but never analyzed.

"Data imbalance occurs when stats are collected by never analyzed."

Technicians are often test-takers and have not been trained in data analysis. The technicians follow designated "routes" or watch lists. They rely on their technology to explain what is happening with the motor. Their data may, in fact, indicate that something requires further examination. However, if there is no indication or alarm triggered during testing, technicians may log the information as "normal recurring events." The data is stored and forgotten much like obsolete equipment in a vast warehouse.

Companies may not be totally cognizant of the need for trending despite their financial commitment to motor management and maintenance. It is not the fault of the technicians, who have been trained to react promptly if their testing technology indicates alarms. If there is no alarm, undertrained technicians may presume that nothing is wrong and move on to the next test. Because trending is so important to motor viability and longevity, companies should educate their technicians to go beyond test-taking and recognize values that could indicate fault zone issues that must be rectified.

The point of motor trending is to identify problem areas before they become catastrophic and prohibitively expensive. That is unlikely when there is no consideration of data value that indicates a trend and potential costly oversight. Management can take advantage of tools like the Site Condition Window that can open motor testing databases and conduct its own analysis. For management, the window is vital – particularly for accessing data that was never analyzed and uncovering trends in fault zones that need to be addressed.

Trending lets you glean meaning from hard data.Trending lets you glean meaning from hard data.

Troubleshooting occurs after a component of the motor shows signs of malfunction, the motor is performing poorly or has failed altogether. All motors will eventually reach an end of life condition no matter how well they have been maintained. The severity of the defect, however, may depend upon how well the company maintained its QC and trending analysis. Troubleshooting will identify the defect and determine whether the problem is fixable (by weighing acceptable downtime and cost balanced against motor age and condition) or it may conclude that the asset is at the end of its life and must be replaced.

As is the case with QC and trending, a well-defined troubleshooting plan is essential if there is any hope of restoring the motor to operational effectiveness. It is incumbent upon the company to include vendors in a written troubleshooting plan at its inception. This approach is better than a more expensive, reactive one, which occurs when companies call for help only when the motor is failing. The vendor can be a valuable resource in getting at the root cause of the problem before it occurs.

"Troubleshooting is not likely to be effective without a guideline."

Above all else, troubleshooting needs a guideline – a detailed checklist that enables identification of root causes and minimizes time to return to productivity. There has to be a troubleshooting procedure that differentiates a fixable repair from end of life. An end-of-life situation in a fault zone may not necessarily mean permanent replacement of the entire motor or the expense of hiring a crane to remove the troubled asset to the repair facility. A power circuit anomaly, for example, can be fixed in place. Fault zone issues such as a stator winding anomaly may or may not be fixable in the factory.

A western coal mine company can vouch for the importance of a troubleshooting guideline. Its coal conveyor belt motor blew the low voltage slip rings and could not be repaired in place. The company had a replacement motor on site and called for the crane for movement and installation because it assumed that start-up would be routine. The assumption was wrong. The motor blew a fuse at start-up and appeared to be rotating in reverse direction. When the direction changed, the motor blew another fuse. Similar efforts led to the same result – a total of six fuses, each valued at $1,000, were ruined, forcing the company to call for help on a Saturday, a day when repair charges are always at their highest.

The electric company that responded used a state-of-the-art technology predictive technology in electric motor testing that uncovered an inductive imbalance in the stator winding. The technology then promptly identified the culprit: two reversed leads causing a phase inversion and a reverse torque that opposed the normal rotation. When the leads were corrected, the motor functioned normally.

The coal company spent approximately $150,000 to correct a problem that would have been identified by a three-minute test before moving the motor into place. The lesson: use predictive technology before calling the crane.

Motor management in a changing industry
Productive and long-lasting operation of motors in today's business environment is the reason for the development of advanced technology and site procedures to increase reliability and assure a quick return to productivity in the event of troubleshooting and repairs. Converting data to usable information becomes more efficient when the analyst has help to make the right decisions. The most effective software creates an environment from point of data, point of analysis and point of decision through data integration and proper alarm set points. So the original question, "How could we have missed this?" is best answered by filling in the gaps.

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