By Noah Bethel, CMRP
Vice President of Product Development
PdMA® Corporation
Introduction
Global competition and economic uncertainty make equipment reliability a top priority for companies of all sizes. An unplanned slowdown or shutdown in today’s marketplace can reduce a company’s productivity and lower their profitability. One industry segment where this issue is on the rise is electric motor testing, as it is essential in improving reliability and maximizing productivity. To accomplish the goal, savvy professionals understand that a steady stream of quality data enables them to safely and successfully analyze, troubleshoot, and maintain motors and their circuits so that efficiency stays high and costly downtime is avoided.
Currently, there are three approaches to testing electric motors and generating the data needed to prevent unplanned downtime, loss of production, and expensive repair or replacement costs. Of these three testing techniques, there is a good, better, and best approach that provides continuous electrical data and immediately sends cell phone notifications if a problem with a motor is detected. When companies choose the right strategy for a particular motor and situation, they can safely collect data, differentiate between good and bad data, and prevent potential issues before they become serious.
Importance of Electric Motor Testing
A recent Forbes magazine article revealed that the average manufacturer experiences approximately 800 hours of equipment downtime annually, which equates to approximately 15 hours a week. That downtime comes with a significant cost. For instance, an automotive manufacturer loses $22,000 per minute when production stops. Unplanned downtime cost industrial manufacturers $50 billion or more a year, a total that includes labor costs, reduced production, and lost revenue. But there are additional “hidden” costs as well, such as parts and materials, shipping, utilities, lost sales opportunities, and customer service issues.
The extraordinary costs associated with electric motor downtime make adopting and maintaining an efficient test program essential in maximizing profits. The right testing approach can also compensate for the industry-wide loss of knowledge and experience, due largely to an aging workforce and a subsequent increase in retirements. Without long-term workers who know a motor “inside out,” the proper testing approach can provide the information company officials need to make good decisions and avoid unexpected downtime.
For example, a recent client of PdMA used the MCEMAX®, widely known as the single most powerful electric motor testing tool currently available, to identify motor overheating that otherwise would have gone unnoticed and eventually lead to severe damage and costly unplanned motor downtime. In this case, while resistance-to-ground measurements were acceptable, the MCEMAX identified a significant drop in winding resistance and inductance. This prompted correlation with thermography and the motor was running with a skin temperature of 40 degrees over the recommended level. A subsequent examination of the motor showed significant heat damage to the insulation caused by an undersized cooling fan. Allowing the motor to continue operating under such conditions caused severe damage to the windings and could have resulted in a fire.
In this situation, comprehensive electric motor testing identified an issue before it advanced and became a costly emergency. The Electric Power Research Institute (EPRI) reported in a recent survey that 48 percent of motor failures are a direct result of electrical failures. As such, it’s more important than ever for companies to consistently test their electric motors. But which testing approaches are available and best for different companies and circumstances?
Types of Electric Motor Testing
PdMA has divided motor testing into three approaches—good, better, and best. PdMA provides technology to support all three methods, and typically, a world-class company would use a combination of all three to maintain its electric motors properly, keep reliability high, and costs as low as possible. Companies that embrace preventive electric motor testing balance portable testing technology with permanently installed testing technology can expect several benefits, including:
- Electric motor testing identifies potential issues before they escalate and become serious problems, thus extending the motor’s lifespan.
- The wide-ranging and highly precise data generated by today’s top electric motor testing equipment allows technicians to address electrical energy issues to reduce loss and lower operating costs.
- Testing reveals potential hazards, such as fire or electric shock, to keep workers safe and ensure motors continue to meet safety standards and regulations.
- The proper testing approach can also uncover issues that negatively impact performance to keep the motor running at optimal speed and energy consumption.
An example of the impact electric motor testing can have on a company is described in a case study involving another PdMA client. This client frequently conducted In-Rush/Start-Up testing. This type of testing, also known as In-Rush current testing, measures the surge of electricity that flows into an electrical device when it is first turned on. With PdMA’s technology, this test can also be conducted when an engine is in a steady-state run to examine torsional and standard load operation, among other operations. Because this large electric motor, which was a 3,000HP, 355RPM, with 240 slots, and 196 bars, and was located underwater in a river, the client wanted as much information as possible to understand what could not be seen. In this case, that attention to detail prevented a potentially catastrophic pump failure.
The In-Rush/Start-Up test discovered severe current fluctuations in the submersible pump motor. These fluctuations led the company to conduct additional testing, including Demodulated spectrum, which revealed a dramatic increase in noise level, a Rotor Evaluation, which showed significant overload, and a Comparison test, which exposed notable operational differences between this motor and a similar one. The testing results pointed to a mechanical issue instead of an electrical one, and when the pump was pulled out of the water, it was discovered that the inlet to the pump was broken.
The inlet was repaired, and the pump immediately returned to smooth operation. If the issue had not been identified and the repair had not been made, the abnormal stress could have led to catastrophic failure, and the company would have had to replace the entire pump rather than just the inlet. That’s the savings companies can realize from adopting the right electric motor testing approach.
Selecting the Right Testing Approach for Electric Motors: The Good Approach
The Good Approach involves using MCEMAX, a portable battery-operated technology, which tests a wide range of motors either online or offline. MCEmax combines the capabilities of online and offline testing into one portable package that can be used on a motor of any size, type, and condition. This technology has variable test voltage from 250 to 5,000v, which enables RTG, PI, or Step Voltage testing. It also offers six-channel simultaneous acquisition and torque and efficiency analysis.
MCEmax starts with the traditional tests (resistance-to-ground and conductivity), which focus on the motor’s insulation and power circuit. MCEmax then adds specialized tests to evaluate other critical aspects of the motor. This expanded testing capability is combined with a user-friendly interface to create a device that helps companies of all sizes.
One of the most significant factors separating MCEmax from others in the marketplace is its comprehensive Six-Fault Zone approach for analyzing electric motors. The MCEmax provides comprehensive data for each specific fault zone—Power Quality, Power Circuit, Insulation, Stator, Rotor, and Air Gap. At a time when electric motors are complex and challenging to diagnose, having access to this extensive information allows company leadership to make the best decisions regarding their electric motors.
Selecting the Right Testing Approach for Electric Motors: The Better Approach
The Better approach involves using the portable, battery-operated MCEMAX technology and MTAPs, including MTAP2® and MTAP3. MTAP2 is PdMA’s initial solution for safe testing of running motors. It offers consistent, accurate, fast acquisition of data and meets the OSHA and NFPA 70E definitions for safe voltage. It also meets CE, UL 508, and CSA 22.2 #14. MTAP3 is current-only and designed to safely capture data in smaller enclosures where the MTAP2 cannot be installed. The MTAPs benefits include that they collect data in seconds and eliminate tag-out and lock-out procedures.
MTAPs are PdMA’s answer to safe electric motor testing. MTAPs measure three voltages and three currents on a three-phase AC motor. They remove human error and improve motor reliability by increasing testing frequency and safety. Combining MTAPs with MCEMAX makes testing easier, faster, and, above all, safer.
The better approach with MTAPs is they improve safety when collecting data from a running motor by ensuring the voltage and current have been reduced to safe levels. Technicians save time using MTAPs by not having to don personal protective equipment (PPE) and making one connection point instead of three.
Selecting the Right Testing Approach for Electric Motors: The Best Approach
Companies looking to ensure maximum performance and safety with their most valuable electric motors will benefit from the Best Approach, which combines MCEMAX and MTAPs with PdMAEYE®. This permanently installed testing technology provides vital information 24/7. PdMAEYE even provides immediate cell phone notification if a motor problem is detected. Powered by PdMA’s MCEGold® software, PdMAEYE issues color-coded alarms (red or yellow) to identify test data outside the acceptance criteria.
In addition, with PdMAEYE, all data is stored in a cloud server that allows it to be viewed anytime and anywhere worldwide. This combination of permanently installed testing and centralized data access utilizing cloud services has elevated “Good” motor reliability testing to “Best” motor reliability testing. With PdMAEYE, companies can watch their motors 24 hours a day while focusing their resources and manpower on other priorities. PdMAEYE provides comprehensive data for five specific fault zones: Power Quality, Power Circuit, Stator, Rotor, and Air Gap. It also offers continuous monitoring, multi-test functions, instant communication, simultaneous acquisition, simple setup, and data checking, is safe, and restarts automatically.
The value of continuous monitoring was demonstrated recently at a pumping station, which utilized the PdMAEYE in its testing protocol. A rotor degradation issue was discovered in a critical motor located at a remote location. Thanks to the PdMAEYE, the company could monitor the rotor fault around the clock and decide when to repair it. Instead of being blindsided by rotor failure and having to arrange emergency repairs at a difficult-to-reach location, the company controlled the situation. It made the repairs when it was most convenient for the company. In addition to preventing potential motor failure, the PdMAEYE also allowed the company better utilize its employees better. Before implementing the PdMAEYE, workers had to drive a truck to the remote location to test the motor, but with the PdMAEYE, they could monitor the motor remotely while working on other important tasks instead. Testing frequency was also increased from approximately once a quarter to around the clock, with no increase in manpower.
In another case study, a cement production facility used the in-depth data provided by the PdMAEYE to detect a significant difference in machine train frequencies between two mills. The elevated machine train frequencies in one of the mills was then associated with the grinding rollers. With that knowledge, the company cleared debris from the mill’s rollers to prevent further damage and increase production.
Preventive Electric Motor Testing Regularly Pays Off
No matter how well a company maintains an electric motor, problems and end-of-life issues will inevitably occur. Installing testing technology to identify concerns early and avoid unplanned downtime and accompanying loss of production is the most effective way to maintain high profitability. This is achieved by implementing a combination of Good, Better, Best testing approaches to ensure critical and less critical motors are monitored sufficiently while staying within manpower and budgetary constraints.
A tool like the PdMAEYE can be a tremendous money saver with the most critical motors. Connecting the PdMAEYE to an electric motor allows 24-hour monitoring of essential assets and captures every In-Rush/Start-Up. Users get the important electrical data they need to make expert business decisions and ensure a maximum return on investment (ROI) for their electric motors. They also avoid expensive emergency repairs and costly unplanned downtime—ensuring continued success for their organizations.
For more information about PdMA and its Good, Better, and Best testing technology, visit www.pdma.com.
About the Author:
Noah Bethel, CMRP, is vice president of product development for PdMA Corporation, Tampa, FL, the leader in the field of predictive maintenance, condition monitoring applications, and development of electric motor test equipment for motor circuit analysis. Tel: (800) 476-6463.
