Archive | Infrared Analysis

59

6:39 pm
May 15, 2017
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Understand Motor/System Baselines

Want to get the most from your electric motors? Think of St. Louis-based EASA (Electrical Apparatus Service Association,  easa.com) as a treasure trove of practical information and its members as a “go to” source for help with specific applications. Consider this insight on motor/system baselines.

— Jane Alexander, Managing Editor

According to EASA’s technical experts, changes in motor/system vibration readings provide the best early warning of developing problems in a motor or system component. Other parameters to monitor may include operating temperature of critical components, mechanical tolerances, and overall system performance, including outputs such as flow rate, tonnage, and volume.

Motor-specific baselines incorporate records of electrical, mechanical, and vibration tests performed when units are placed in operation or before they’re put in storage. Ideally, baselines would be obtained for all new, repaired, and in situ motors, but this may not be practical for some applications. These baselines typically include some or all of the following:

randmLoad current, speed, and terminal voltage

Changes in these parameters usually indicate that a vital system component is damaged or about to fail. Other electrical tests may include insulation resistance, lead-to-lead resistance at a known temperature, no-load current, no-load voltage, and starting characteristics.

QUICK TIP: Some changes in the current and speed may be normal, depending on the type of load.

Motor current signature analysis (MCSA)

This test diagnoses squirrel cage rotor problems, e.g., broken bars or an uneven air gap. It’s more accurate if a baseline is established early in the motor’s life.

Mechanical tests

These normally consist of measuring shaft runout (TIR) and checking for a soft foot.

Vibration

Although overall vibration readings can be used as baseline data, Fast Fourier Transform (FFT) spectra in all three planes at each bearing housing are preferred (see “Vibration Analysis” on page 22). Shaft proximity probes can be used to determine sleeve bearing motor baselines.

Infrared thermography

This tool can detect changes in the operating temperature of critical motor components, especially bearings.

New-motor baselines

Comparing factory terminal winding resistance and no-load amps with data taken under load can be useful when monitoring the condition of a new motor or troubleshooting system problems. Factory baselines are often available from the manufacturer or its website. The accuracy of factory data depends on how it was obtained, but it’s usually sufficient for field use.

Baseline data for a newly installed motor could reveal an error, e.g., misconnection for an incorrect voltage, and prevent a premature motor failure. Rather than simply “bumping” a motor for rotation before coupling it to the load, operate it long enough to measure the line current for all three phases, as well as the voltage and vibration levels.

QUICK TIP: Comparing the baselines of a failed motor and its replacement could reveal application- or process-related weaknesses in the system.

Repaired motor baselines

Service centers usually provide no-load and/or full-load (when stipulated) test data for repaired motors, including voltage, current, and vibration spectra. Comparing these results with historical baselines and those obtained on site when the motor is returned to service may confirm the quality of the repair or possibly reveal underlying system problems. For example, increased vibration levels in on-site tests might indicate a deteriorating motor base or a problem with the driven equipment rather than a balancing issue with the motor.

With newly repaired motors that have been in operation for many years, baseline comparisons are invaluable in root-cause failure analysis and may even expose consequential damage from certain kinds of failures, e.g., a broken shaft. To correctly identify cause and effect and prevent recurrences, always investigate equipment failure at the system level. MT

For details on using motor/system baselines, as well as expert advice on a wide range of other motor-related issues, download Getting the Most from Your Electric Motors, or contact a local EASA service center.

164

6:01 pm
May 15, 2017
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Use IR Switchgear Windows Properly

IR windows provide a measure of safety and reduce labor by allowing thermographers to inspect switchgear without opening panel covers. (Photo courtesy of Fluke Corp.)

IR windows provide a measure of safety and reduce labor by allowing thermographers to inspect switchgear without opening panel covers. (Photo courtesy of Fluke Corp.)

By Jim Seffrin, Director, Infraspection Institute

In an effort to reduce the risk of injuries associated with arc flash, many sites have installed infrared (IR) transmissive windows or ports that permit IR inspections of switchgear without the need to open panel covers. Although such devices can provide a measure of safety and help to reduce labor associated with those inspections, they pose unique challenges not associated with direct line-of-sight imaging.

Switchgear windows are typically constructed of a rigid frame with a fixed IR transparent material that enables an imager to view through them. Switchgear ports consist of a rigid frame with small openings through which an imager may be sighted. Depending upon type, some feature a single hole, others incorporate metal screens containing multiple holes.

randmIR windows will always attenuate infrared energy received by the imager. While this attenuation affects qualitative and quantitative data, the greatest challenge involves temperature measurement. Accurate temperature measurements can’t be obtained through a screened port. Furthermore, the ability to accurately measure temperatures through an IR window is possible only if the following conditions are met.

• The window opening must be larger than the imager’s lens objective.
• The target must be at or beyond the imager’s minimum focus distance.
• Values for window transmittance and target emittance must be known and properly entered into the imager’s computer.
• The imager’s lens must be kept perpendicular to and in contact with the window.

When it is not possible to meet all of the above conditions, imagery should be evaluated only for its qualitative value. As always, any inexplicable hot or cold exceptions should be investigated for cause and appropriate corrective action taken. MT

Words to the Wise: Beware Hidden Electrical Danger

Getting ready for an infrared inspection of electrical equipment often requires manual preparation of switchgear components, which could be a riskier endeavor than many people might think. Unwary thermographers and other personnel can, in fact, be injured through contact with cabinets or component surfaces that have become accidentally or unintentionally energized.

Switchgear enclosures and components are generally designed to prevent their surfaces from becoming energized. Under certain circumstances, however, enclosures and other dielectric surfaces can become unintentionally energized to significant voltage levels. This potentially lethal condition can be caused by improper wiring, faulty equipment, or contamination due to dirt or moisture.

When conducting infrared inspections on or near electrical equipment, always keep the following in mind:

• Only qualified persons should be allowed near energized equipment.
• Treat all devices and enclosures as though they are energized.
• Never touch enclosures or devices without proper PPE (personal protective equipment).
• Do not lean on or use electrical enclosures as work surfaces.
• Always follow appropriate safety rules.
• Know what to do in case of an accident.

Working alone near exposed, energized electrical equipment isn’t just dangerous, it’s a violation of federal law. Thermographers who perform infrared inspections on any electrical equipment should never work alone. Since CPR can’t be self-administered, at least two people trained in first aid and CPR must always be present when working near most exposed, energized equipment. Having a second CPR-trained person along not only satisfies OSHA requirements, it may save your life.

To paraphrase a time-honored electrician’s admonishment, remember that while there are old thermographers and bold thermographers, there are no old, bold ones.

Jim Seffrin, a practicing thermographer with more than 30 years of experience in the field, was appointed to the position of Director of Infraspection Institute (Burlington, NJ), in 2000. This article is based on several of his “Tip of the Week” posts on IRINFO.org. For more information on electrical systems, safety, and other infrared-related issues, as well as various upcoming training and certification opportunities, email jim@infraspection.com or visit infraspection.com.

330

4:15 pm
April 13, 2017
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Reliability Changes Lives

Using skilled technicians and advanced technology, Eli Lilly and Company creates life-saving medicines and devices worldwide.

By Michelle Segrest, Contributing Editor

Throughout the halls of the Indianapolis Eli Lilly and Company facility, the corporation's brand is proudly displayed. All photos courtesy of Eli Lilly and Company.

Throughout the halls of the Indianapolis Eli Lilly and Company facility, the corporation’s brand is proudly displayed. All photos courtesy of Eli Lilly and Company.

At Eli Lilly, the motivation to improve production reliability is not just something that is tracked on graphs and charts for upper management to review. In fact, for maintenance and reliability engineer Carrie Krodel, it’s personal.

Krodel, who is responsible for maintenance strategies at the Eli Lilly Indianapolis facility’s division that handles Parenteral Device Assembly and Packaging (PDAP), has a family member who uses the company’s insulin. “I come to work every day to save his life,” she said. “Each and every one of us plays a part with reliability. Whether it’s the mechanics or the operators keeping the line running, the material movers supplying the lines with the products, or the people making the crucial quality checks, everyone is a part of it. And we all know that the work we are doing is changing lives.”

The Indianapolis site covers millions of square feet with nearly 600,000 assets that must be maintained. According to Rendela Wenzel, Eli Lilly’s global plant engineering, maintenance, and reliability champion, the company produces the medicine as well as the packaging for insulin pens, cancer treatments, and many other products and devices.

For the entire Eli Lilly team—which includes a group of about 80 engineers at the Indianapolis site—the responsibility is crucial. “If we mess up, someone gets hurt,” Wenzel said. “This is a big responsibility.”

However, it’s the human element of this responsibility that inspires an exceptional level of quality.

Team, tools, training

Screen Shot 2017-04-13 at 11.03.07 AMWayne Overbey, P.E., is the manager of the Maintenance-Manufacturing Engineering Services department. He said his team of seven maintenance technicians uses three primary technologies every day to keep the machines running—vibration analysis, oil analysis, and infrared technology. With a focus on condition-based monitoring, each team member has an area of responsibility to collect and analyze vibration data. In addition to the vibration data collector, each team member carries a small infrared camera to make heat-signature images used to diagnose and troubleshoot rotating-equipment problems.

The team also uses a digital microscope that can zoom to 3500X magnification. This helps them look closely at a bearing race, cage, and rolling elements and see what caused a failure, whether structural, corrosion-based, or failed lubrication. In addition, the group has an oil laboratory that can analyze oil and grease. 

The team performs more than 7,000 measurements on more than 4,000 rotating/reciprocating machines and performs vibration analysis on those machines monthly, Wenzel stated. The level of qualified individuals is high. “Anything that is process related, we have the equipment to look at it and analyze it,” she said. “We have people with ISO 18436-2 Cat 2 and Cat 3 verifications and even one expert with an ISO18436-2 Cat 4 certification, and there are fewer than 100 people globally with that level of certification. These guys are experienced, high-level certified professionals.”

The maintenance team increased its level of performance more than five years ago when it made the strategic decision to outsource the facilities (buildings and grounds) portion of maintenance. With about 220 maintenance professionals companywide at the Indianapolis facility, this allowed the team to focus more on production and analysis rather than the facilities, Overbey said.

The team has sophisticated data-collection routes set up as PMs and also focuses heavily on maintenance training.

“We have a difficult time finding people interested in maintenance,” Overbey said. “We have a strategic program to train people that takes 18 months to 2 years. When I was growing up, being an electrician or mechanic was a fine career, but now the attitude is that you have to have a college degree to be successful. Most of our crafts people here make more than the average liberal-arts major. As we cycle out the baby boomer work force, we need to find new talent and close the gap.”

Wenzel agreed that finding qualified crafts people has been a focus that has helped Eli Lilly in its drive for reliability.

“Wayne saw the need and developed an excellent program,” she said. “Management is supportive. He is training them and then sending them to get experience while they are going to school.”

The program is responsible for hiring 24 trainees, to date, and has been able to place 18 of them in full-time positions within Lilly maintenance groups. The remaining six trainees are still in the initial stage of the program. The training also uses basic maintenance programs provided by Motion Industries and Armstrong. Last year, there were more than 30 well-attended training classes focused on equipment used at Lilly. The company wants the training to be relevant to what the maintenance technicians perform on a daily basis.

“The whole condition-based platform makes us unique,” Wenzel said. “We have all the failure-analysis competencies. It’s a one-stop shop. We provide two-to-three day courses on condition-based technologies for crafts and engineers. The whole understanding, as far as what maintenance and reliability can do, is to increase wrench time and uptime. We are all seeing an uptake in technology.”

The Indianapolis Eli Lilly facility has more than 600,000 assets that must be maintained by its experienced engineering-services team.

The Indianapolis Eli Lilly facility has more than 600,000 assets that must be maintained by its experienced engineering-services team.

Best practices

Overbey stated that his main responsibility is to help the various site-maintenance groups improve uptime by using diagnostic tools to identify root causes of lingering problems. With a focus on training paying dividends, he said the high-quality people are what make the condition-based monitoring team successful.

The team works with the site-maintenance groups to reduce unexpected failures, so increased time can be focused on preventive maintenance. “We look at our asset-replacement value as a function of our total maintenance scheme,” Wenzel said. “We look at recapitalization and make sure we are reinvesting in our facility. We keep track of where we are with proactive maintenance. Those numbers are tracked facility to facility and then rolled into a global metric.”

Vibration analysis and using infrared technology has become a central part of the department’s reliability efforts.

“These guys have taken responsibility for the failure-analysis lab and taken it on as an added-value service,” Wenzel said. “For example, if there is a failed bearing, they take it out, cut it up, and provide a report that goes back to management. If we make a call that a piece of equipment has increased vibration levels and is on the path to failure, based on the vibration data collected, getting those bearings goes a long way in getting site buy-in when the actual bearing problem can be visually observed. Most individuals are skeptical when shown the vibration waveform (squiggly lines), seeing the bearing with the anomaly is the true test of obtaining their buy in.”

“We can compete with anyone in terms of oil analysis,” Wenzel added. “We can identify particles and have switched to synthetics. For example, when oil gets dirty, it becomes acidic. Something slightly acidic can be more harmful than something that is highly acidic because it will just continue to eat away at the material and cause significant damage before you can stop it. Something slightly acidic can really tear up bearings. The FluidScan 1100 can detect that.”

Screen Shot 2017-04-13 at 11.03.19 AM

More than 80% of the oil samples are now handled internally, Wenzel said. “As we are selling all of these capabilities to the PdM team around the world, we are starting to look at some of the potential issues at other facilities to provide extra analysis with this condition-based maintenance group,” she said. “We are sharing good ideas and processes across facilities. We now have a maintenance and reliability community.”

Eli Lilly employs Good Manufacturing Practices (GMP) and the use of many chemicals requires a high level of cleanliness that is checked daily and regulated by government bodies.

Changeovers can often take weeks. “We check everything,” Wenzel said. “There is very involved and stringent criteria for how we clean a building. Regulations are a challenge, but they keep you on your toes. You don’t even notice it anymore because it becomes a part of what you do. It doesn’t faze the day-to-day thinking.”

The precision and accuracy of the facility's manufacturing equipment contributes to its product excellence.

The precision and accuracy of the facility’s manufacturing equipment contributes to its product excellence.

Operational excellence

Eli Lilly works with cross-functional teams in which maintenance, engineering, and operations are working on the overall process. Operations manager Jason Miller is responsible for running the process. Maintenance corrects the issues and performs preventive maintenance to get ahead of equipment failures and prevent unplanned downtime.

“Anytime we have an equipment failure we evaluate what happened and see what process we can put in place to get ahead of those things,” Miller said. “Line mechanics are on each shift and work with our line operators to understand and troubleshoot issues. We get ahead of issues to ensure [there is] no impact to the quality of our process.

With advanced robotics and a large amount of automation, monitoring performance and quality is key to successful operation and production, Miller stated. “Everything is captured, including downtime and rejects,” he explained. “We identify corrective actions at every morning meeting. We use the data on the line to drive improvement. The line is automated, but if there is a reject every 100 cycles, we need to take action. The robotics never stop. If you see overloads or rejects over time, this tells you about mechanical wear and other issues with the equipment. We drive data-driven decisions for maintenance.”

The preventive maintenance includes lubricating linear slides each month. When vibration is detected, adjustments are made immediately. “The machines tell us what’s going on. We just have to know how to read them,” Miller said. “We have manual and visual quality checks, but the machines also do quality checks. Reliability is critical because when patients are waiting on their medicine, the machines have to run the way they are supposed to run all the time. We have standards, and they have to be precise. This is medicine going into someone’s body. We are the last step of the process. It has to be packaged and labeled correctly, as well.”

Mike Campbell is the maintenance planner and scheduler for PDAP and has developed a system in which all preventive maintenance is performed during scheduled shutdowns.

“We develop a schedule with every piece of equipment and every scheduled PM associated with it,” Campbell said. “One line may have 50 to 60 PM work orders to perform during the week of the scheduled line shutdown. We bring in a lot of resources to do it all at once, typically requiring a day shift and a night shift.”

Advanced production technology is critical to the standard of reliability excellence.

Advanced production technology is critical to the standard of reliability excellence.

Changing lives with reliability

Wenzel said that looking at how each department interacts helps to put all the pieces of the reliability puzzle together. They have even received outside recognition of their practices in Indianapolis. In 2008, The Corporate Lubrication Technical Committee, of which Wenzel is the chair, won the ICML John Battle Award for machinery lubrication.

“It’s not only a cost piece, there is a whole asset-management piece and a whole people piece that we have to look at–not just the numbers, the metrics, the bars and charts–it’s the whole thing that makes a facility tick,” she explained. “Reliability isn’t just my job…it is everyone’s job. Every time I get into my car and turn the key, I expect it to come on. Every time I run that piece of equipment, I want it to perform the same way every time. That, to me, is reliability.”

Overbey said reliability is about being tried and true. “It’s predictable. It’s reliable every day. It’s the whole conglomeration of things that is very complicated, yet very simple. When all is said and done, reliability is a huge advantage for a company. You are only spending money when you need to. But it’s very difficult to get there.”

Wenzel said that consistency is a key to reaching reliability goals. Eli Lilly has global quality standards and good manufacturing practices that are applicable to each of the company’s sites across the world.

“Reliability means the equipment is ready each and every time it runs, and it should perform the same way each time,” Krodel said.

Doug Elam is Level 4 vibration certified, which is a rare level of qualification. He works on Overbey’s team and also tried to define reliability. “Reliability is an all-expansive subject that touches on different types of technology, the goal of which is to improve efficiency in machinery performance,” Elam said. “It requires an intense study of the background functions of the machines.”

Eli Lilly and Company uses robots on an assembly line to carefully package its products.

Eli Lilly and Company uses robots on an assembly line to carefully package its products.

Regardless of the definition, reliability for Eli Lilly always circles back to the human element.

“Patients come through and perhaps are on insulin or a certain pill, or a cancer treatment that has changed their lives,” Wenzel explained. “We listen to them, because it’s not just the medicine that matters, but the packaging and ease of use. It puts what we do in perspective. We take this feedback and incorporate it into our designs. It starts with an end user’s idea and need, goes to design, goes through production, then back to the end user. It’s like a circle of life.”

The research is carefully conducted with the end user always in mind.

“A lot of research is done to make the best fit for each subset of people,” Wenzel continued. “And at the end of the day you have a marketable product that you can be proud of. Being on both sides of the business, you understand why medicine is so costly. But when you find the one niche that helps cancer patients, or the kid who is near death, and then you can be a part of developing this medicine that completely changes his life, it just makes it all worthwhile.”

And yes, it’s personal.

“When you know people who use the products,” Wenzel said, “the work you do becomes a part of you.” MT

Michelle Segrest has been a professional journalist for 27 years. She specializes in the industrial processing industries and has toured manufacturing facilities in 40 cities in six countries on three continents. If your facility has an interesting maintenance and/or reliability story to tell, please contact her at michelle@navigatecontent.com.

280

6:39 pm
February 10, 2017
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Infrared Inspections Of Installed Motors

By Jim Seffrin, Infraspection Institute

randmDespite the important role they play in facilities, electric motors often tend to be out of sight and out of mind—until they fail. Infrared thermography can be a cost-effective diagnostic tool for detecting problems within these systems.

Many infrared (IR) inspection programs focus on motor control circuits, but overlook the actual motors. Infrared inspections of a motor’s bearings and stator should be performed monthly by an experienced, certified IR thermographer that thoroughly understands the theory and operation of electric motors.

Here are the basic steps for performing this type of inspection:

1. Inspect motor casing for localized hotspots that may be indicative of short circuits within motor windings.

2. Qualitatively compare individual motors to similar motors under similar load.

3. When possible, qualitatively compare inboard and outboard bearings for each motor. If a large Delta T is present, it may be indicative of misalignment or a rotor balance problem. If both bearings are hot, the bearings may be worn or improperly lubricated.

4. Additionally, a thermographic inspection of the electrical connections within the motor junction box should be performed annually. This may be done in conjunction with a regularly scheduled IR inspection of the facility’s electrical system.

Because no complicated analysis is required, infrared inspections typically can be performed rapidly and at a fraction of the cost of other types of motor testing. Infrared can also detect evidence of misalignment at lower thresholds than those detectable by vibration analysis and motor-current signature analysis. MT

Words to the Wise: Stick to Facts

0217rmcinfraWhen used as a preventive/predictive maintenance tool, infrared (IR) thermography can detect and document evidence of thermal patterns and temperatures across the surface of an object. The presence of inexplicable thermal anomalies or exceptions is often indicative of incipient failures within inspected systems and structures. Because thermography alone can’t determine the cause of an exception, other diagnostic tools must be employed.

Some thermographers, however, provide opinions as to the cause of exceptions without the benefit of confirming test information. Such opinions are frequently accompanied by elaborate recommendations for repair. When those observations/recommendations are incorrect, they can cause repair efforts to be misdirected.

Unless a thermographer has performed, or has access to, confirming tests, it’s unwise to provide opinions regarding the cause of exceptions and offer suggestions for repair. Lacking confirming test data, a prudent thermographer should make only one recommendation: “Investigate and take appropriate action.”

This simple recommendation can be applied to any thermographic inspection and serves to avoid unnecessary liability by eliminating guesses and sticking to facts.

— J.S.

Jim Seffrin, a practicing thermographer with 30+ years of experience in the field, was appointed to the position of Director of Infraspection Institute, Burlington, NJ, in 2000. This article is based on one of his “Tip of the Week” posts on IRINFO.org. For more information on infrared applications, as well details on upcoming training and certification opportunities, email jim@infraspection.com or visit infraspection.com.

460

8:24 pm
February 9, 2017
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Listen for Impact

Above. Josh Mattson's desktop computer screen displays dB data collected from ultrasound probes that feed software to generate an oil-analysis report. Oil analysis has become a big part of reliability best practices at USG Interiors by providing insight as to when to filter oil, change oil, identify early signs of failure, or use to assist in analyzing data from other technologies such as ultrasound or vibration monitoring.

Josh Mattson’s desktop computer screen displays dB data collected from ultrasound probes that feed software to generate an oil-analysis report. Oil analysis has become a big part of reliability best practices at USG Interiors by providing insight as to when to filter oil, change oil, identify early signs of failure, or use to assist in analyzing data from other technologies such as ultrasound or vibration monitoring.

Josh Mattson drives key reliability programs using ultrasound and root-cause analysis. Continue Reading →

508

2:43 pm
August 10, 2016
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Heed Drive-Belt Temperature Limits

randmBy Jim Seffrin, Infraspection Institute

Temperature is frequently used to gauge the condition of motors and power-transmission equipment. The following information applies to flexible drive belts and the temperature limits for them.

Drive belts are an integral component on many types of machines. Despite the critical role they play in machine operation, V-type drive belts tend to be out of sight and out of mind until they fail. In most installations, belt temperature largely influences the life of installed V belts.

As a rule of thumb, properly applied and maintained belts should not exceed 140 F (60 C), assuming an ambient temperature of less than 110 F (43 C). Belt life can be greatly reduced by higher operating temperatures. In fact, for every 18 F-deg. (10 C-deg.) increase in belt temperature, belt life is cut in half. Keeping this in mind, we can see that the life of a drive belt operating at 176 F would be reduced by 75%.

Thermogram shows overheating V-belts. Note castoff in the control photo. Images courtesy of Skip Handlin.

Many factors contribute to high belt-operating temperature, including, but not limited to, ambient air temperature, machine design, installation, alignment, and belt tension. Overheating belts that afford line-of-sight access can be readily detected and documented with an infrared imager.

Issues associated with overheating in drive belts may not be limited to the belts themselves, however. With regard to over-tensioned drive belts, excessive force applied to belts is often transferred to bearings in the driven system. In these situations, it’s not uncommon to see bearings overheat due to the excess force created by the over-tensioned belt(s).

Thermogram shows the effects of an improperly tensioned V-belt. In this example, over-tension causes both the belt and adjacent pillow block bearing to run hot.

It should be noted that the operating temperature of overheating drive belts is not necessarily linear. A worn belt that has reached critical temperature will begin to wear at an accelerated rate, which, in turn, will cause the belt to run hotter and wear even more quickly. This vicious cycle will continue until the belt either breaks or fails to perform its intended task.

Once detected, overheating belts should be investigated for cause and proper corrective measures undertaken as soon as possible. Doing so can help prevent unscheduled downtime and may prolong belt life.

Thermal imaging offers several distinct advantages over other types of inspections for belted systems. Thermal imaging is non-contact and nondestructive. Imaging is performed remotely and requires no shutdown of inspected systems. Because infrared imagers produce real-time data, results are instantaneous and allow rapid inspection. MT

Jim Seffrin, a practicing thermographer with 30+ years of experience in the field, was appointed to the position of Director of Infraspection Institute, Burlington, NJ, in 2000. This article is based on one of his “Tip of the Week” posts on IRINFO.org. For more information on infrared applications, as well details on various upcoming training and certification opportunities, email jim@infraspection.com or visit infraspection.com.

208

10:03 pm
June 13, 2016
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Use Thermal Imagers To Identify Motor Trouble

Making and cataloguing thermal images part of your regular preventive maintenance routine will help determine when and what motor components are varying from their baseline.

Making and cataloguing thermal images part of your regular preventive maintenance routine will help determine when and what motor components are varying from their baseline.

Infrared cameras, also called thermal imagers, can be important tools for troubleshooting motor problems, as well as for monitoring motor conditions for preventive maintenance. Infrared images reveal a motor’s heat signature, which can tell you a lot about its condition. The condition of motors, in turn, can play an important role in keeping plants up and running and their operating costs down.

According to experts at Fluke Corp., Everett, WA, here are some tips for scanning motors and drives with thermal imagers:

Build motor heat-signature profiles.
Capture good quality infrared images when the motors are running under normal operating conditions. That gives you baseline measurements of component temperatures. Make infrared images of all of the critical components, including motor, shaft coupling, motor and shaft bearings, and the gearbox. Note that when working with low electrical loads, the indications of a problem can be subtle. As a load increases, the temperature will increase. If a problem exists, expect greater temperature differences at higher loads.

Note nameplate information and hot spots.
A motor’s normal operating temperature should be listed on the nameplate. An infrared camera cannot see the inside of the motor, but the exterior surface temperature is an indicator of the internal temperature. If a motor is overheating, the windings will rapidly deteriorate. Every 50-deg. F increase in a motor’s windings, above the designed operating temperature, cuts the winding life by 50%, even if the overheating is only temporary. If a temperature reading in the middle of a motor housing comes up abnormally high, an IR image of the motor can tell you where the high temperature is coming from, i.e., windings, bearings, or coupling. If a coupling is running warm it is an indicator of misalignment.

Know the three primary causes of abnormal thermal patterns.

  • High-resistance contact surface, either a connection or a switch contact, often appears warmest at the spot of high resistance.
  • Load imbalances can appear equally warm throughout the phase or part of the circuit that is undersized/overloaded. Harmonic imbalances create a similar pattern. If the entire conductor is warm, it could be undersized or overloaded. Check the rating and the actual load to determine the cause.
  • Failed components typically look cooler than those that are functioning normally. The most common example is probably a blown fuse. In a motor circuit, this can result in a single-phase condition and the possibility of costly damage to the motor.

Create regular inspection routes and compare images.
It is a best practice to create a regular inspection regimen that includes making thermal images of all critical motor/drive combinations. Ideally, these images are made under identical operating conditions to have apples-to-apples comparisons. Comparing current state images with baseline images can help you determine whether a hotspot is unusual and also help you verify if any repairs undertaken were successful. A thermal imager can easily transfer images into software for cataloguing. Sharing can be invaluable in this effort. MT

For more information on thermal-imaging best practices, visit fluke.com.

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