The new PKL Series interval impactors from Martin Vibration Systems are designed to deliver the force needed to dislodge sticky materials from process vessels, chutes, pipes, storage bins and dust collectors. The very high acceleration generates individual blows similar to a hammer, while reducing noise and energy costs, as well as the potential for bin damage and injury. Based on individual application requirements, the company can supply interval impactors providing from 120-1700 pounds of force to move material that resists the effects or rotary vibration. 

“The PKL Series is very effective at moving sticky materials from a wide range of storage vessels,” says Mike Lindbeck from Martin Vibration Systems. “It also works well clearing dusty residues and breaking up accumulation, helping bulk material handlers avoid bridging and ‘ratholing’ that can strangle flow rates,” he said.

With variable impact frequency from 10 to 60 per minute, the PKL 2100 can be tuned to suit specific material characteristics and operating  environments, minimizing noise, energy costs and equipment damage without the need for an external timer. The low operating frequency combined with the “air-against-spring” design translates to very low energy usage, yet the new impactors deliver 30% more force than preceding designs. 

The PKL Series Impactors can operate from supplied air pressure from 45-115 PSI, with a 5-micron filter, pressure regulator and lubricator. They are designed for a maximum operating temperature of 250ºF (121ºC), with high-temperature models capable of handling up to 320ºF (160ºC). 

Options include stainless steel construction, ATEX certification and portable Vac-MountTM units. Available in six different body sizes, the PKL Series is well suited for use on spray dryers, transfer pipes, cyclones, chutes and ash hoppers. By effectively preventing build-up and blockages, the units contribute to greater process efficiency, while helping to reduce maintenance and downtime. All PKL Series Impactors are covered by a full 3-year warranty when operated within recommended limits.
www.shake-it.com

In simplest terms, vibration in motorized equipment is the back-and-forth movement, or oscillation, of machines and components, such as drive motors, driven devices (such as pumps and compressors) and the bearings, shafts, gears, belts and other elements that make up mechanical systems. Vibration in industrial equipment can be both a sign and a source of trouble. Other times, it just “goes with the territory” as a normal part of machine operation and should not cause undue concern.

But how can a maintenance professional tell the difference between acceptable vibration and the kind that requires immediate attention to service or replace troubled equipment?

Vibration is not always a problem. In some tasks, vibration is essential. Machines like oscillating sanders and vibratory tumblers use vibration to remove materials and finish surfaces. Vibratory feeders use vibration to move materials. In construction, vibrators are used to help concrete settle into forms and compact fill materials. Vibratory rollers help compress asphalt used in highway paving.

In other cases, vibration is inherent in machine design. For instance, some vibration is almost unavoidable in the operation of reciprocating pumps and compressors, and internal combustion engines. In a well-engineered, well-maintained machine, such vibration should be no cause for concern.

When vibration is a problem
Most industrial devices are engineered to operate smoothly and avoid vibration, not produce it. In these machines, vibration can indicate problems or deterioration in the equipment. When the underlying causes are not corrected, the unwanted vibration itself can cause additional damage. This article focuses on machines that are supposed to vibrate as part of normal operation, but on those that should not vibrate: electric motors, rotary pumps and compressors, and fans and blowers. In these devices, smoother operation is generally better, and a machine running with zero vibration is the ideal.

Causes
Vibration can result from a number of conditions, acting alone or in combination. Keep in mind that vibration problems may be caused by auxiliary equipment, not just the primary equipment. These are some of the major causes of vibration.

Imbalance
A ‘heavy spot’ in a rotating component will cause vibration when the unbalanced weight rotates around the machine’s axis, creating a centrifugal force. Imbalance could be caused by manufacturing defects (i.e. machining errors, casting flaws) or maintenance issues (i.e. deformed or dirty fan blades, missing balance weights). As machine speed increases, the effects of imbalance become greater. Imbalance can severely reduce bearing life as well as cause undue machine vibration.

Misalignment/shaft runout
Vibration can result when machine shafts are out of line. Angular misalignment occurs when, for example, the axes of a motor and pump are not parallel. When the axes are parallel but not exactly aligned, the condition is known as parallel misalignment. Misalignment may be caused during assembly or develop over time due to thermal expansion, components shifting or improper reassembly after maintenance. The resulting vibration may be radial or axial (in line with the axis of the machine) or both.

Wear
As components such as ball or roller bearings, drive belts or gears become worn, they may cause vibration. When a roller bearing race becomes pitted, for instance, the bearing rollers will cause a vibration each time they travel over the damaged area. A gear tooth that is heavily chipped or worn, or a drive belt that is breaking down, can also produce vibration.

Looseness
Vibration that might otherwise go unnoticed may become obvious and destructive when the component that is vibrating has loose bearings or is loosely attached to its mounts. Such looseness may or may not be caused by the underlying vibration.
Whatever its cause, looseness can allow any vibration present to cause damage, such as further bearing wear, wear and fatigue in equipment mounts and other components.

Effects
The effects of vibration can be severe. Unchecked machine vibration can accelerate rates of wear (i.e. reduce bearing life) and damage equipment. Vibrating machinery can create noise, cause safety problems and lead to degradation in plant working conditions. Vibration can cause machinery to consume excessive power and may damage product quality.

In the worst cases, vibration can damage equipment so severely as to knock it out of service and halt plant production.

Yet there is a positive aspect to machine vibration. Measured and analyzed correctly, vibration can be used in a preventive maintenance program as an indicator of machine condition, and help guide the plant maintenance professional to take remedial action before disaster strikes.

Characteristics of vibration
To understand how vibration manifests itself, consider a simple rotating machine like an electric motor. The motor and shaft rotate around the axis of the shaft, which is supported by a bearing at each end.

One key consideration when analyzing vibration is the direction of the vibrating force. In our electric motor, vibration can occur as a force applied in a radial direction (outward from the shaft) or in an axial direction (parallel to the shaft). An imbalance in the motor, for instance, would most likely cause a radial vibration, as the heavy spot in the motor rotates creating a centrifugal force that tugs the motor outward as the shaft rotates through 360 degrees.

A shaft misalignment could cause vibration in an axial direction (back and forth along the shaft axis) due to misalignment in a shaft coupling device. Another key factor in vibration is amplitude, or how much force or severity the vibration has. The farther out of balance our motor is, the greater its amplitude of vibration. Other factors, such as speed of rotation, can also affect vibration amplitude. As rotation rate goes up, the imbalance force increases significantly.

Frequency refers to the oscillation rate of vibration, or how rapidly the machine tends to move back and forth under the force of the condition or conditions causing the vibration. Frequency is commonly expressed in cycles per minute or Hertz (cpm or Hz). One Hz equals one cycle per second or 60 cycles per minute.

Though we called our example motor “simple”, even this machine can exhibit a complex vibration signature. As it operates, it could be vibrating in multiple directions (radially and axially), with several rates of amplitude and frequency. Imbalance vibration, axial vibration, vibration from deteriorating roller bearings and more could all combine to create a complex vibration spectrum.

Conclusion
Vibration is a characteristic of virtually all industrial machines. When vibration increases beyond normal levels, it may indicate only normal wear, or it may signal the need for further assessment of the underlying causes, or for immediate maintenance action. Understanding why vibration occurs and how it manifests itself is a key first step toward preventing vibration from causing trouble in the production environment.

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This article is based on the Fluke white paper “Introduction to vibration.” For more information, visit www.flukecanada.ca.

Emerson Process Management has expanded the application of its CSI 9420 Wireless Vibration Transmitter with intrinsic safety ratings to the U.S., Canadian, and European standards. With the Class I, Div 1 and ATEX Zone 0 ratings, the CSI 9420 can now be installed directly in hazardous areas such as chemical, petrochemical, and off-shore facilities as well as other explosion-classified environments.

The CSI 9420 connects quickly, easily, and economically to any machine. The safety ratings, which are in addition to existing hazardous area ratings to the Brazilian and IECEx standards, further extend the benefit of wireless technology to new areas of the plant. The CSI 9420 provides key insights into the condition of pumps, fans and other assets located in hazardous areas without the expense of running cables.
www.emersonprocess.com

A plant engineer’s ability to diagnose, detect and monitor equipment condition issues is advancing all the time, thanks to ongoing developments with vibration, thermography (infrared), oil analysis and ultrasound tools, just to name a few.

So once you have all the fancy new tools, do you know how best to take advantage of them?

We’re here to help. Along with the sophistication of the tools available, ways to synthesize and integrate data so that maintenance teams can make immediate use of it and also monitor trend issues over a period of time are also progressing. PEM asked leading technology providers to share the latest in their condition monitoring tech developments, how best to integrate them, and where the future is headed.

Infrared
Over the last few years, infrared cameras have improved significantly in terms of resolution and now come with more options as well, says Paul Frisk, manager of the Infrared Training Center in Burlington, Ont. (the training arm of infrared camera-maker FLIR Canada Ltd.). “Infrared cameras now have the ability to incorporate wireless data from digital clamp meters and other instruments and make that all available at one glance,” he explains. “Some cameras now available immediately generate a single-page report. This summary can be transferred for printing and archiving by download to an office computer or through wifi to a plant’s CMMS system.”

Frisk says the primary value of an infrared camera is in its ability to initially determine whether a device is working properly or not while it’s running. “With some other diagnostic tools, you have to shut down the device, which obviously impacts production,” he notes. However, as with many types of detection and monitoring technology, there are misconceptions about what infrared cameras can provide.

“From watching movies and TV, people think infrared cameras can allow you to see through walls, water, etc., but they only measure released infrared energy,” he explains. “A properly trained thermographer can determine temperatures from infrared readings using conversion factors, knowing the material and so on, but infrared cameras cannot overcome the physics of all materials under all conditions.” He also stresses that infrared images can easily be misinterpreted, and proper training is absolutely necessary.

In addition to using handheld infrared cameras and connecting them with your plant’s CMMS, standalone infrared cameras can send data to the process PLC (programmable logic controller). “Based on the camera’s readings, things like process speed, fans or heat can automatically be adjusted if the material needs to be kept at a certain temperature,” Frisk notes.

With regard to the future of infrared condition monitoring technology, he foresees more improvement in resolution and smaller camera size, along with a continued drop in cost.

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Ultrasound
Ultrasound instruments have changed a great deal over the past decade, according to Alan Bandes, vice president of marketing at UE Systems. Analog detectors, which required manual entry of test results for basic trouble-shooting, have been replaced by software-driven digital systems capable of analyzing trends and reporting on a wide range of operating conditions. Newer models offer things like sound analysis, cameras, non-contact infrared thermometers, and even touch screen controls. “There are a lot of professionals that haven’t looked at ultrasound technology closely and view the instruments as basically leak detectors,” Bandes says. “Others feel, incorrectly, that ultrasound is too subjective, which is often due to experience only with older analog units.”

Bandes says it’s very easy to integrate ultrasound technology into plant processes. “Due to the sophistication of on-board software and external supportive software, users can create routes, establish baseline information and upload and download route data,” he explains. With baselines set, the software can notify personnel with low-level alarms (for example, lubrication starvation) or high alarms (failure) through headphones or other means.

Some instruments provide inspectors with the option of opening up a spectral analysis screen to analyze bearing faults, gear mesh issues and electric emissions while in the field. Recorded sound samples can be played in real-time and viewed with an image of the spectral screen. “This feature is very useful for electrical emissions as well as mechanical operations,” he notes.

Software associated with ultrasound instruments can provide specialized reporting for things like steam traps, valves and bearings. “Regarding leak surveys, downloaded test results can be converted into reports that provide important information for cost analysis and greenhouse gas emissions,” Bandes says. Regarding the future of machine monitoring by ultrasound, he believes “we are only limited by the software we can develop.”

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Oil analysis
More vendors now supply in-plant oil analysis sensors and the means to communicate with those sensors. “It's no longer necessary to rely solely on a lab for analyzing oil samples to determine fluid condition,” says Darren German, Bosch Rexroth national service manager. “In the plant, we can now get real-time results on of oil cleanliness (particle count), water content and temperature when sensors are coupled with a data acquisition device.” These devices can record and track trend parameters in real time for any given time period, but German cautions maintenance teams that monitoring equipment should be considered as a compliment to a bottle sampling program; reports from an oil analysis lab still provide the most oil condition information. The role of monitoring equipment is to provide additional protection between bottle sampling periods, he says. “If, for example, a heat exchanger ruptures and releases water into the oil the day after a bottle sample was taken,” he notes, “this will likely go unnoticed until production stops if there is no oil analysis sensors in place.”

The many oil-monitoring systems on the market range in complexity and price. “Some of the data acquisition systems also provide the ability to add a threshold or alarm which will signal the moment the results vary from a ‘baseline normal,’ ” he says. “We suggest that before investing, you should understand what it is that you want to accomplish — what parameters are important to monitor.” He recommends that maintenance groups consult with their engineering groups prior to purchasing a system, as the ability for a machine to communicate with a sensor often already exists within the machine HMI.

German predicts that down the road, the capacity to measure reliable viscosity and TAN (total acid number) will be developed, along with a sensor that can measure the amount of air in hydraulic fluid. “ ‘Smart’ sensors and wireless sensors are often mentioned as coming down the pipe as well,” he says.

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Vibration
Advances over the last few years in sensor, recording, and analysis technology have put vibration analysis within the reach of even small companies, says John Bernet, product and application specialist at Fluke Corp. “Easier measurement procedures (triaxial sensors), combined with vibration diagnosis programs (expert systems) now enable maintenance teams with minimal training and experience to use vibration to evaluate machine health and determine required maintenance,” he notes.

Bernet says vibration can identify problems before other symptoms, such as heat, sound, electrical consumption and lubricant impurities, are detected. “Measuring the vibration of motors, pumps, and other common machines can reveal valuable information about machine health or impending failures,” he notes. “However, instead of focusing on the patterns of the hundreds of faults that vibration analysis can reveal, we should focus on the four most common mechanical faults: imbalance, misalignment, wear, and looseness.” He adds that studies have found that many vibration analysis programs don’t collect all the data needed to make an accurate diagnosis — to diagnose machine condition correctly, vibration data is needed from all three axes of a rotating shaft.

The key to automating vibration analysis, he notes, is to compare new data with data from a similar machine known to be functioning properly. Automated diagnostic programs perform a sophisticated analysis, comparing hundreds of data points with the fault patterns of similar machines to give easy-to-understand results.

Bernet foresees that the benefits of vibration analysis will be expanded to the entire plant in future. “A plant’s reliability team can use high-end analysis programs on the few complex machines, while the maintenance team can use simple diagnostic tools on the basic machines,” he says.  p

Treena Hein is a freelance writer based in Pembroke, Ont.

Fluke Corp. introduces the Fluke 805 vibration meter, a portable multifunction vibration screening tool that provides quantifiable information on the bearing and overall health of motors and other rotating equipment.

It is ideal for frontline mechanical troubleshooting teams that need reliable and repeatable measurements of rotating equipment to make imperative go/no-go maintenance decisions.

The Fluke 805 measures:

• Overall vibration – The 805 measures overall vibration from 10 to 1,000 Hz and provides a four-level severity assessment for overall vibration and bearing condition.
• Bearing condition (CF+, or Crest Factor Plus) – The 805 Vibration Meter detects peaks in the vibration signal readings of roller bearings from 4,000 Hz to 20,000 Hz, and uses a proprietary algorithm to interpret severity to determine if the bearing is going bad.
• Surface Temperature – An infrared sensor automatically measures contact temperature and displays it along with the vibration reading for a broader understanding of machine health.

The 805 Handheld Vibration Meter has a unique sensor tip design that minimizes measurement variations caused by device angle or contact pressure. This reduces operator error and improves the accuracy and repeatability of quick vibration screening. The meter also provides a severity scale for both overall vibration and bearing condition readings, delivering more information than comparable vibration pens. Logged data can be easily uploaded into Excel to create trending reports.

The Fluke 805 Vibration Meter will be available in June at a U.S. list price of US$1,799.95.
www.fluke.com

Bearings are critical components of machines and with proper performance monitoring, imminent failures can be identified and corrected. However, without a monitoring program in place, and subsequent corrective actions taken, a single bearing failure can result in full machine shutdown and countless hours of lost production.

Bearing monitoring is guided by three main senses: sight, sound and touch. Basic monitoring is conducted through elemental observations. However, many highly sensitive tools are available that amplify these observations so they are more noticeable, recordable, and include basic logic to assist with warning identification.

Visual Monitoring
Monitoring bearings visually through classical methods include observing lubricant condition, corrosion, and deterioration. Mounted bearings that are lubricated properly will purge grease from their seals. The condition of the grease upon purging can indicate improper relubrication intervals and/or contamination. Dark, cakey or milky grease are visual signs that relubrication intervals and procedures may be improved.

Evidence of corrosion is a valuable monitoring tool as well. High levels of corrosion can degrade material strength and performance. Deterioration of the surface, seals, or obvious physical dimensional characteristics should also warrant further investigation. These observations are often signals of wear, heat and other abnormal performance prior to total bearing failure.

Several monitoring tools commonly available to leverage visual observations include site gauges for oil lubricated bearings, and thermal imaging guns. Bearings that are lubricated by oil rather than grease are often fitted with site gauges, which will give an indication of the presence of oil and the quantity of oil available to the bearing. These gauges are practical and inexpensive.

Audible Monitoring
Traditionally, audible monitoring is one of the most common methods of monitoring machinery because odd noises are obvious indicators of improper operation, even to the untrained user. It is conducted quickly through an operator’s daily routines. After all, if a bearing within the machine doesn’t sound well it usually isn’t well.

The main problems with bystander audible observations is that (1) it usually identifies the later stages of bearing failure, when planning downtime for bearing replacement is impractical and (2) when audible feedback of a single bearing is masked by the overall noise of its environment. That’s when instruments such as stethoscopes (with amplification) and decibel level meters are advantageous. Both tools are available with a wide range of features that include quantified readings and recording features so bearing performance can be trended. These tools are also more useful at identifying improper operation at a less threatening stage of failure.

Bearings should run quiet and smooth; anything different will likely reflect a flaw or a problem with the bearing itself. Noises such as grinding or banging should be investigated quickly. These noises may indicate complete bearing failure and continued use may lead to catastrophic failure and/or damage to neighboring equipment. Bearing noises such as light clicking and squealing may indicate looseness, faults or skidding and should be inspected for cause and remedy.

Audible evaluation is not as sensitive as other monitoring techniques. It is primarily a method of identifying a failure more so than identifying poor performance. Additionally, audible monitoring in the early stages of failure is more noticeable at higher operating speeds than lower speeds.

Physical (Touch) Monitoring
Monitoring bearings by touch, and then trending the observations against historical performance is by far the most useful and accurate means for assessing bearing condition and predicting bearing failure. The touch method can be used to monitor temperature, vibration, and lubrication. 

Operating temperature is the most practical and beneficial monitoring method for bearings because expensive tools are not required and is appropriate to all types of applications; slow to high speeds, light to heavy loads. For example, the average threshold of pain for humans is approximately 130°F. If it is difficult to maintain hand-to-bearing contact for several seconds then the temperature is likely above 130°F. Furthermore, water droplets placed on a bearing housing that quickly boil will indicate that the bearing temperature will have easily exceeded 212°F.

There are also many useful tools available to measure and monitor bearing temperatures. The most common include thermocouples and resistance temperature detectors (RTDs), both of which can be permanently mounted to locations on the bearing housing for continuous real-time monitoring. Temperature switches are also available that can be utilized for warning and/or shutdown at dangerous operating temperatures. Many bearing manufacturers offer various permanently mounted sensors pre-installed in bearing housings in areas that will most accurately reflect the true bearing temperature, rather than the housing skin temperature.

Portable thermal imaging tools are also a quick and efficient means to monitor bearing performance. These tools use infrared thermography to visually identify variations in temperature over a broad area.  However, the most common portable temperature measurement tool is the infrared thermometer. Although it does not measure temperatures over a broad area, they are inexpensive and easy to use.

Monitoring and trending bearing temperature is important because as a bearing fails, the temperature will continually increase. Trending temperature over time will help identify a failing bearing in the early stages of failure.

Vibration analysis is the most information-rich method available for bearing analysis, and touch can help identify smooth versus rough operation. As safety permits, feel the housing during operation. Rough operation, jostling, or grinding may indicate a bearing problem.

You may also consider vibration measurement instruments to not only identify stages of bearing failure, but also identify overall machine performance and problems. Sensors mounted to the bearing may include permanently mounted or portable magnetic base accelerometers, displacement probes, or velocity pickups. Sensor selection is dependent upon the bearing speed, sensitivity requirements and the application. Although vibration feedback is highly beneficial, proper training is important due to the complexity in data collection and interpretation. 

Simple tests can also be conducted on purged grease to detect hard particle contaminants. Upon relubrication, rub some of the freshly purged grease between fingertips. Gritty grease may indicate a need to lubricate more often or wear from a failing bearing.

Many traditional and advanced options are available to monitor and evaluate bearing performance. Leveraging instrumentation to support traditional observations is a valuable practice in support of a predictive maintenance program.

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Galen Burdeshaw is Baldor’s customer order engineering manager for DODGE bearings and power transmission components. For more information, visit www.baldor.com.

Eckert Machines introduces Advanced Detection Systems (ADS), which produces the ProScan series metal detectors, with their patented vibration compensation program. This eliminates the oft-cited problem of false rejects and optimizes metal detection to ensure food safety. ProScan systems are available for bulk product (conveyor, pipeline, or free-fall) as well as packaged or cased product. ADS systems are custom manufactured to each processor’s needs.
www.eckertmachines.com

To the savvy maintenance professional, industrial machinery almost “talks” to reveal its condition. But the real key to success is in understanding what the machine is saying. To detect potential machine problems, the professional “listens” in many ways:

• With thermometers and thermal imagers, to detect overheating, poor electrical connections or failing bearings;
• With digital multimeters and power analyzers, to diagnose electrical problems; and
• Using techniques like lubricant analysis, to gauge machine condition over time.

Today, the maintenance professional has a new way not just to listen but to find mechanical problems and fixes: the Fluke 810 vibration tester is engineered to detect and evaluate machine vibration and recommend any needed repairs.

In one case study, a major oil company had to keep 40 electric motors on the job, pumping crude oil, propane and other petroleum products down the pipeline. That task is now easier for one 35-year industry veteran, the area logistics manager for the company. For the past year, he’s been using the vibration tester to diagnose issues in pumps, blowers, and motors up to 3,500 horsepower that pump 8,000 barrels an hour.

“This is something I’ve been waiting on for quite some time,” he said. “The ones we’ve used in the past give you the vibration signature, but you had to interpret the signature. The problem with that is you need to get that in the hands of a technician who knows how to read your signature. The neat thing about it is the Fluke will give you its idea of what it thinks is wrong. But it also gives you that signature you can give to the engineers.”

 “We went down to our transport station — we’ve got eight mainline units there — and were able to find some bearing problems on one of our units,” the logistics manager said. “Once we got the pump into the shop we found out the shaft was out of round, which took the bearing out.

“We went to our number eight pump, and it said ‘motor-pump misalignment.’ The coupling has a shim pack — it’s kind of a flex coupling. That was on a 400 horsepower. We thought we might have a misalignment on the motor but it turned out we had a broken shim pack. We fixed it and it’s still running today, with no problem. It really surprised me how it picked that one up. I don’t know how it did that.”

Ease of use is another advantage. “You can give this thing to just about anybody, and they can learn how to use it in a matter of a few minutes. You can log all your equipment, you can pair it up with Fluke’s infrared camera and it will give you a full picture.”

Today, the Fluke 810 delivers results fundamental to the company maintenance program. “With the big motors, we do the vibration analysis, we look everything over on an annual basis with the Fluke imager so we can see if there’s any heat rise, and we use it on all the switch gear. I call it shoot-fix-move on.

“A lot of companies like to bring people in who actually do the vibration analysis and thermal imaging for ’em,” he said. “The problem is they’ll send you a report but it’s three months down the road, and here you’ve been running this piece of equipment that’s had an issue for over three months.” But with the new tester, “once you’ve got your technicians trained you just shoot, fix and move on.”

With a typical vibration program, he added, “I was spending probably $16,000 just to do the first pass. I can put this $8,000 piece of equipment in their hands and get the same performance.”

In the world of mechanical maintenance, vibration remains one of the earliest indicators of a machine’s health. Mechanical equipment is typically evaluated by comparing its condition over time to an established baseline condition. Vibration analyzers are designed specifically for maintenance professionals who need to troubleshoot mechanical problems and quickly understand the root cause of equipment condition.

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Colin Plastow is industrial product manager for Fluke Electronics Canada. He may be contacted at This e-mail address is being protected from spambots. You need JavaScript enabled to view it . For more information, visit www.flukecanada.ca.

Unplanned downtime caused by equipment failures costs manufacturers up to three percent of revenue every year. That’s 30 percent less profit. In an era of extreme competitiveness, no one can let that kind of money slip through their fingers.

Much of this cost can be avoided with proactive maintenance, such as measuring key indicators on critical equipment to discover impending failures and then scheduling maintenance. This practice is far more effective than waiting to perform maintenance when a failure happens, because it allows you to plan downtimes, minimize disruption and ensure spare parts are always available when needed.

Proactive maintenance programs and tools can vary from highly sophisticated processes for continuous online monitoring and automated alerts to more traditional offline programs that rely on inspection routes and manual measurements. Before looking at the tool sets needed, it is important to first establish some basic guidelines that should be support every proactive maintenance program:

• For each type of equipment, identify the potential failures and related key indicators.
• Determine what measurements can reduce the likelihood of problems.
• Determine how often equipment needs to be measured.
• Collect and track the results, watch for trends, and initiate repairs as needed.
• Integrate all of your maintenance technologies into one computerized data tracking system so they share the same equipment lists, histories, reports, and work orders.

With these ground rules in mind, we can now look at the measurement parameters and basic test tools needed when developing a proactive maintenance program.

Insulation resistance to ground testing
This test should be conducted regularly on loads and connections to detect imminent equipment failure. Ground testing line and load circuits at the starter will identify the resistance to ground of the starter, line circuits to the disconnect, and load lines to the motor and starter windings. Note that when using an insulation resistance tester for ground testing, disconnect the components or cabling to be tested from the power system.
Tool needed: Insulation resistance tester.

Temperature
Infrared thermometers are a low-cost monitoring option for quick, frequent measurements of specific components while equipment is operating. Use knowledge of the equipment to identify key hot spots to track, compare those temperature readings to operational limits and watch for upward trends. For the best measurements, get as close as is safely possible to the target, make sure the measured surface is not reflective and compensate for emissivity.

Thermal imagers are versatile tools that can play a key role as screening tools. Users can use them to quickly measure and compare heat signatures for each piece of equipment on an inspection route without disrupting operations.

Users can also quickly survey a much larger area than an infrared thermometer, and see how the temperatures of different areas relate to each other. If the temperature or thermal pattern is markedly different from previous readings, use other maintenance technologies — such as vibration, motor circuit and lubricant analysis — to assess the severity of the problem and time needed to repair it.
Tool needed: Infrared thermometer, thermal imager.

Vibration testing
Vibration is often an indication of problems with or deterioration in the condition of the equipment. If the underlying causes of excessive vibration are not corrected, the unwanted vibration alone can often cause additional damage.

Measurements are taken by placing an accelerometer near each bearing location along the drive train, using the most appropriate attachment method. It is important to ensure proper sensor placement in order to collect good data.

For consistent data over time, place the accelerometer at the exact same location each time you take a measurement. Also, be sure to take vibration measurements when the machine is running in a steady state and at normal operating temperature. (Machines tested while still cold may have significantly different vibration signatures.)

Use a vibration tester, such as the Fluke 810, to analyze the data to determine the source, location and severity of the faults, and identify potential mechanical problems weeks, if not months, prior to a failure.
Tool needed: Accelerometer, vibration tester.

Resistance
A digital multimeter (DMM) can be used to check the resistance across most connections. Before beginning, remember that resistance measurements must be made with the circuit power off. In addition, high-resolution DMMs can measure the resistance across relay and circuit breaker contacts.

Infrared thermometers can also be used to identify high resistance connections, which show up as hot spots when compared to a good connection.
Tool needed: Digital multimeter, infrared thermometer.

Current
AC and DC loads may draw slightly higher current as they age. Regularly measuring current can help you track equipment reliability. Use either a clamp meter or a DMM combined with a current clamp to measure current.

Another root cause for equipment overheating is current imbalance. A more-than-10-percent current imbalance can be a problem. Use a clamp meter or an AC current clamp with the DMM to check the current draw on each of the three legs.
If a motor isn’t performing correctly or if the circuit is tripping unexpectedly, check inrush current at startup with a clamp meter or a DMM designed to capture inrush current. Evaluating inrush current depends on comparisons of inrush measurements over time for that motor.
Tool needed: Clamp meter, CMM with current clamp.

Voltage balance
A greater-than-two-percent voltage imbalance can reduce equipment performance and cause premature failure. Use your DMM to check voltage between phases for voltage drops at the protection and switchgear delivering power from the utility and at high priority equipment. Voltage drops across the fuses and switches can also show up as imbalance at the motor and excess heat at the root trouble spot. Before a user assumes they’ve found the cause, they should double check with a thermometer.
Tool needed: Digital multimeter.

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Colin Plastow is industrial product manager for Fluke Electronics Canada. He may be contacted at This e-mail address is being protected from spambots. You need JavaScript enabled to view it . For more information, visit www.flukecanada.ca.