Thermography is widely used to detect defective connections for supply/return conductors within electrical distribution systems. Thermography can also be used to detect loose/deteriorated connections within bonding and grounding systems.

In a perfect world, substation structures and protective fencing surrounding the sub would never become energized. In the REAL world, substation structures and nearby metal components can, and often do, become energized either by leakage current or induction. For safety, all structures near and within the substation are electrically bonded together and wired directly to ground in order to carry this unwanted and potentially lethal power to ground.

Because grounding systems frequently carry current, loose or deteriorated connections will often manifest themselves as hot spots at or near the source of the problem. Because a loose grounding conductor can compromise the integrity of the grounding/bonding system, any inexplicable hot spots should be investigated as soon as possible regardless of temperature rise.

It is recommended that hot spots within a grounding system should be given top priority. Should a grounding connection fail, anyone making contact with the energized portion of the structure could be seriously or fatally injured.

A follow up inspection should be performed once any repairs have been made to ensure that the subject repairs were effective.

“Stretchers”, “tall tales” and “selective interpretation of the truth” are politically correct terms that apply to statements that are misleading or false. With no editorial controls, the world wide web is rife with deceptive claims. Because thermography is not immune to inaccurate web postings, thermographers should be cautious in their acceptance of material posted on the web.

Prudent web surfers frequently view material on the internet with a healthy amount of skepticism. All too frequently, the amount of caution is inversely proportional to value of the product being advertised. Further compounding the problem are unscrupulous advertisers who publish misleading information. Some current examples include:

• Brochures for thermal imagers containing images taken with a different model imager
• Publication of specifications that are incomplete or inaccurate
• Literature and trade names suggesting imager models for inappropriate applications
• Obsolete imagers renamed and offered as current models, although manufacturer support is no longer available

For equipment purchases, the above are often exacerbated when the reader is untrained and/or inexperienced with the technology. Before purchasing a thermal imager, be sure to try the subject equipment under the exact conditions you will encounter in the workplace.

When it comes to the internet, the old adage, “You can’t always believe everything you read” is frequently sage advice.

As concerns regarding indoor air quality increase, there is increasing concern with respect to mold. Used properly, a thermal imager can help identify areas of potential mold growth.

Mold is a ubiquitous single cell organism that tends to favor moist environments. Of the thousand species of mold found worldwide, many are harmless; however, certain species are toxic. Others can cause chronic health problems in humans.

While thermal imagers cannot detect mold directly, they can often detect evidence of the latent moisture often associated with mold presence. When using a thermal imager to detect latent moisture, keep the following in mind:

• Evidence of moisture can only be detected if a temperature differential exists across the surface of the material being inspected.
• Frequently, a delta T can be created by actively heating or cooling a structure or by relying on solar loading of the subject areas.
• Subject building components should be imaged from both indoor and outdoor aspects under the correct weather conditions.
• Suspected moisture presence must be confirmed by independent means.
• A negative finding for latent moisture does not guarantee that mold is not present.

Since moisture presence is not positive proof of mold presence, further laboratory tests will be required to confirm mold within any moist areas detected.

Many thermographers think of the holidays as a time for family, festivities and annual maintenance of their infrared equipment. Planning ahead can help to minimize imager downtime and avoid or minimize program interruption.

Because infrared test equipment plays a key role in an inspection program, minimizing downtime required for service is imperative. Keeping the following in mind can help routine service to proceed more smoothly and ensure a faster turnaround for your imager.

• Schedule routine equipment service and/or calibrations well in advance
• 
  Most service departments require you to obtain a Return Authorization before shipping equipment
• 
  Be sure to include all optics and filters when shipping your system
• Consider scheduling service before or after holidays to avoid service backlogs
• Arrange for replacement equipment if you anticipate a long delivery time for service

When shipping your equipment, enclose a letter stating services required and any problems with the subject equipment. Be sure to affix a Packing List to the exterior of your shipping container noting descriptions and serial numbers of items shipped. Lastly, don’t forget to ascertain Customs requirements if your equipment must be shipped outside of your country for service.

According to the laws of physics, only a perfect blackbody may have Emittance of 1.0. Although the E value of real objects must be less than 1.0, some radiometers allow entry of E values exceeding 1.0. The following describes how these radiometers achieve the impossible.

Emittance is a measure of how well an object radiates energy when compared to a blackbody at the same wavelength and temperature. Emittance for any object is measured on a scale between 0 and 1.0. Since blackbodies (E=1.0) exist only in theory, real world objects will have E values of less than 1.0. The E value of an object can never exceed 1.0.

Assuming that most objects are opaque (T=0), they must be somewhat reflective. When making an infrared temperature measurement, this reflected energy represents an error source. To overcome errors due to reflections, quality radiometers have inputs for reflected temperature. By measuring reflected temperature and entering this value into the radiometer’s computer, this error source is compensated for in the radiometer’s software.

Less sophisticated radiometers often lack inputs for reflected temperature. To compensate for this, these radiometers allow the user to exceed E values of 1.0. Although this overcompensation may allow the user to match a desired reference temperature, it can lead to significant errors. For infrared temperature measurement, the best solution is to use quality radiometric equipment and eliminate or avoid reflections whenever possible.

Overlooked and underappreciated until they fail, batteries supply the lifeblood of portable test equipment. Proper care of rechargeable batteries can extend service life and maximize run time.

Current choices in rechargeable battery types sound like a recipe for alphabet soup: NiCd, NiMH, and Li-Ion. Advancements in technology have made portable batteries more reliable while reducing required care. Safely obtaining optimum battery performance and longevity is easy if you observe the following:

• Never use batteries for anything other than intended use
• Discharge batteries fully before recharging
• Charge batteries only with the appropriate charger in a well-ventilated area
• Disconnect batteries from charger when charging is complete
• Assign batteries to a specific charger to allow for easier troubleshooting should charger fail
• Inspect charger cables and connections for cleanliness and integrity on a regular basis
• Periodically exercise batteries by discharging and recharging

Lastly, batteries are not immortal. Following the above can help to extend battery life; however, one should plan to replace rechargeable batteries at regular intervals or when run times shorten appreciably. Always dispose of defective batteries properly and recycle whenever possible.

Infrared inspections of flat roofs are a time-tested procedure for detecting evidence of subsurface moisture within a roofing system. Current standards specify infrared inspections be performed from the exterior of the building; however, infrared inspections may be performed from the interior of the building under certain conditions.

Thermography is a dynamic technology. New applications are constantly being developed and existing methodologies are constantly being improved. As an alternative to imaging from the exterior of the building, some have suggested inspecting the underside of the roof deck from the interior of the building

When selecting a vantage point for an infrared roof inspection, the most important consideration is roof construction. Commerical roofs constructed with relatively thin decks and no air spaces between system components may be inspected from either indoors or outdoors.

Prior to tackling an infrared roof inspection from the interior of the building, the following conditions must be met.

• Roof surface should be clean and dry
• Line of sight access to subject roof areas is required
• Space beneath the roof deck should be uniform temperature
• Viewing locations should be selected to eliminate interference from hot or cold objects such as HID lanps and HVAC equipment

Lastly, inspection must be timed to ensure adequate delta T exists between wet and dry insulation. Upon completion of infrared inspection, all data should be veirified by invasive testing.

When performing infrared inspections in hazardous or hard-to-reach areas, a remote monitor screen can be a valuable accessory. Combining an after-market LCD monitor or camcorder equipped with a monitor screen can provide a cost effective solution for expanding the functionality of your imager while increasing safety.

Thermal imagers with monocular viewfinders require a thermographer to stand in front of the object being inspected. This requirement can compromise safety by exposing a thermographer to hazardous or high temperature objects.

Several modern thermal imagers offer remote monitor screens as either a standard feature or as an accessory. Traditionally, LCD monitors available from imager manufacturers have been expensive. As a result of technological advancements, a wide array of LCD monitors are now available at affordable prices.

Since many thermal imagers have video output jacks, it is possible to connect an external LCD using a standard video cable. When selecting an external monitor, keep the following in mind.

• Ensure imager video output is compatible with the chosen monitor
• Consult monitor specs to confirm suitability for chosen environment
• Use high quality cables to reduce signal loss
• · Beware of tripping hazards that can be caused by onnecting cables

Lastly, choose a monitor with sufficient resolution, brightness and contrast to provide a quality image.

Thermography is a proven technology for finding many types of defects within electrical systems. While infrared inspections can assist in PdM efforts, they can also point out a potentially lethal condition that can lead to electrocution and death.

Many AC electrical devices are wired with a grounding conductor. Ungrounded metallic structures and devices can become unintentionally energized if a bare circuit conductor makes contact with the subject structure. In ungrounded structures, improper wiring or defective/deteriorated insulation can allow the structure to become energized up to full circuit voltage. In such cases, anyone touching the energized structure may be electrocuted or fatally injured. One such fatality occurred in May, 2003 when a nine year-old boy made contact with an energized light pole in Columbus, Ohio.

On at least three separate occasions in 2003, thermographers have found evidence of energized structures with a thermal imager. All three findings involved outdoor metal light poles which exhibited inexplicable hotspots where the pole was bolted to the concrete footing. In the Columbus case, a nearby steel fence post also exhibited an inexplicably hot base where bolted to the concrete sidewalk.

For reference we have included thermal images of one of the aforementioned light poles. We urge thermographers to be on the lookout for this potentially lethal thermal anomaly and to immediately notify appropriate personnel should you detect evidence of this condition in the future.

Thermal images show base of metallic light pole operating in excess of 180ºF due to ground fault condition.

With awareness of infrared technology at an all time high, point radiometers have become a common tool in many areas. Frequently, knowledge of proper operation lags behind instrument popularity. Understanding how spot measurement size affects accuracy is imperative to collecting meaningful data.

All radiometers are limited by a characteristic known as spot measurement size or spot size, for short. Spot size is determined by a radiometer’s detector and optics. Typically, spot size increases as distance to the target is increased. For accurate temperature measurement, spot size must always be smaller than the target being measured. When using a point radiometer, be sure to keep the following in mind:

• Point radiometers are usually supplied with a Distance to Spot Ratio value. To determine spot size, divide distance to target by ratio value.
• Point radiometers have minimum focus distances. At lesser distances, spot size will not decrease.
• Single, laser-generated aiming dots do not represent spot size
• Multiple, laser-generated aiming circles/dots often understate spot size
• Beware of stated spot size ratio values. Spot size ratios are frequently quoted at 90% radiance (accuracy) or less

When using a point radiometer, be sure to understand the limits of your instrument and the challenges presented by your target. Always use correct emissivity values and stay within the limits of your instrument.

For years, many thermographers have sought to qualify the severity of detected exceptions by measuring temperature rise. Although this technique is widely practiced, failure to understand key issues can lead to misdiagnoses and unplanned downtime.

For over 25 years, thermographers have frequently attempted to qualify the severity of detected exceptions by comparing the temperature of the exception to similar components under similar load or to ambient air temperature. Although qualifying exception severity may be desirable for maintenance planning, it also involves a certain degree of risk management as some exceptions may rapidly deteriorate and lead to an unplanned outage.

To better understand the risks associated with assigning severity to exceptions based upon temperature, it is important to keep the following in mind:

• For highly reflective targets, small emissivity errors can cause significant infrared temperature measurement errors
• Infrared temperatures are subject to errors due to spot measurement size
• The source of an exception may be contained within a device prohibiting direct measurement at the point of origin
• IR temperature measurement is subject to significant errors due to atmospheric conditions such as wind, solar gain and moisture
• The temperature of electrical exceptions can increase dramatically and without warning if arcing should occur
• Qualifying exception severity based upon temperature does not consider the potential impact of an unplanned failure

At present, there is no scientific method for accurately predicting time to failure based upon operating temperatures of electrical or mechanical components. In order to reduce the likelihood of an unplanned failure, every exception detected should be investigated for cause and properly repaired as soon as possible.

Infrared inspections of oil filled transformers can help to increase reliability and extend transformer life. Detecting hotspots on the bushings of these transformers may also help to prevent a catastrophic explosion.

Hot spots on transformer bushings are usually due to a loose or deteriorated electrical connection. Frequently, the source of a hot bushing connection is external to the transformer and can be corrected by repairing the defective connection. However, loose connections which originate within the transformer case can represent an extremely dangerous condition.

Loose electrical connections within an oil-filled transformer can lead to a condition known as arcing. When arcing occurs in oil, the molecular structure of the transformer oil breaks down forming several combustible gases. The most significant gases produced are acetylene, hydrogen, methane, ethane, and ethylene.

The amount of gas produced will depend upon the temperature of the arc and length of time; however, even small amounts of gas can lead to a potentially explosive condition. In a sealed, oil-filled transformer these gasses can build to a potentially explosive level within a very short time. In short, combustible gases combined with an arcing condition within a transformer are a recipe for potential disaster.

When inspecting oil filled transformers, any inexplicable temperature rise on bushings should be investigated and corrected immediately. Performing a dissolved gas analysis of the transformer oil is recommended if the cause of the problem is suspected to originate within the transformer.

For years, thermographers have traditionally reported apparent Delta T measurements when documenting their findings. Using a default emittance value between .8 and 1.0, apparent temperature measurements are recorded regardless of actual target emittance. While this methodology is fast and easy, it can lead to significantly understated Delta T repair priorities.

The temperature displayed by a radiometer is largely dependent upon the emittance and reflected temperature values entered into the radiometers computer. Typically, errors in either of these settings will cause temperature measurement errors that are exponential in nature and can cause large errors in reporting Delta T’s.

Example: Using an emittance value of 1.0 a thermographer measures the apparent Delta T between two, uninsulated electrical bus bars to be 44ºC. How much can observed temperature vary due to emittance values?

From the above, the following observations can be made:

• Emittance can have a significant impact on Delta T measurements
• The greater the variation between an object’s true emittance and radiometer settings, the more understated the Delta T
• Repair priorities may be significantly understated if accurate emittance values are not utilized

As there is no way to correct for errors introduced by apparent Delta T measurements, thermographers should utilize correct emittance values whenever possible. As always, all thermal anomalies detected during an infrared inspection should be investigated and proper corrective measures undertaken as soon as possible.

Infrared inspections of electrical distribution systems frequently include motor controllers. Proper imager settings and inspection technique are imperative In order to accurately inspect these critical electrical devices.

Industrial motors of all sizes are frequently controlled by remote devices known as motor controllers. Motor controllers are small to large metal-clad devices containing one or more large solenoids that control starting/stopping, motor speed, and rotation direction.

Motor controllers often contain a number of electrical devices operating at widely differing temperatures. These devices include control circuits, transformers, fuses, circuit breakers, contactors, thermal overloads, and circuit conductors. The temperature of these devices can range over hundreds of degrees.

When performing an infrared inspection, setting a thermal imager’s controls to encompass the whole motor control in a single view is not recommended as significant problems can be overlooked. For best results, we recommend the following:

• Ensure that subject motor controller is under load
• Image from a distance that permits viewing only of the subject controller components.
• Perform inspection in direction of line to load side of motor control circuit
• View subject components individually
• Adjust level/gain settings to optimize image for each component inspected
• Compare features of similar components to each other, noting inexplicable differences

For controllers with multiple contactors, it will be necessary to inspect each contactor individually while under load. Be sure to allow sufficient time for subject contactor to achieve running temperature.

Loose connections, overloading and imbalanced loads cause overheating of components within an electrical system. Depending upon construction and operation of the electrical system, a perplexing and possibly serious condition called inductive heating can cause non-current carrying components to overheat.

As current flows through an electrical circuit, a magnetic field forms around the conductor. When current flow is high, a strong magnetic field can develop and extend for several inches around the subject conductor(s). If ferrous materials such as steel are positioned within this magnetic field, they can heat up even though they are not part of the circuit.

Inductive heating can occur on bus supports, cable tray fasteners, bushing skirts and switchgear enclosures. Affected components can become hot enough to cause significant heat damage or even skin burns. The temperature of the affected component will depend upon the strength of the magnetic field, and the composition and location of the affected component.

Because inductive heating can cause components to reach temperatures of over 200ºF, thermographers should pay particular attention whenever combustible materials or dielectric insulation are located near, or in contact with, an inductively heated item.

Most modern thermal imagers utilize a Focal Plane Array (FPA) detector. Although the term FPA is widely used, it is frequently misunderstood. Since detector type can affect imager performance it is imperative to understand the differences among FPA detectors.

The term Focal Plane Array is a non-standard industry term which applies to modern thermal imagers that utilize a detector chip with multiple picture elements configured in a flat, single-plane array. Each pixel of an FPA is an independent sensor capable of detecting infrared energy. When arranged in an integrated array, these pixels form a sensor capable of producing relatively high resolution images compared to older, single or multi-element scanned detectors.

At present, there are two distinct types of FPA detectors:

• Cooled FPA
• Microbolometers (Uncooled FPA)

Cooled FPA imagers are short wave only, contain a Stirling cycle cooler and require approximately 5-7 minutes of cool-down time after initially turning on the unit. Cooled FPAs were initially imtroduced in the mid 1990’s and revolutionized thermography with their small size and high resolution imagery. They have been largely replaced by market demand for uncooled microbolometer imagers.

Uncooled FPA imagers or microbolometers are long wave only, do not contain a cryogenic cooling system and typically require less than one minute to produce an image after initially turning on the unit. Uncooled FPAs were first introduced in the late 1990’s and have seen many improvements over time. Nearly every thermal imager currently being offered for PPM and PdM applications utilizes a microbolometer detector.

The benefits of thermography for condition assessment of insulated roofs are well documented. Performed on a regular basis, infrared thermography can help to extend the overall life of a roofing system when utilized as part of a preventive maintenance program.

As a building component, roofing systems tend to be out-of-sight and out-of-mind. Despite the critical role they play in keeping a facility dry, many roofs garner little attention until they begin to leak. In order to minimize damage, it is imperative that roof leaks be detected and repaired at an early stage.

Many roofs can gain significant quantities of moisture in a very short period of time. In the case of retrofitted roof systems, whole roof sections can become saturated in a matter of weeks while leaking little or no water into the occupied spaces. By the time a roof leak is noticed within the building, replacement may be the only option available.

For best results, insulated roofs should be thermographically inspected at least twice per year (e.g. Spring and Autumn) in accordance with published standards and guidelines. Semi-annual infrared inspections can help to identify new areas of moisture damage and help to ensure that recent repairs are performing in a watertight manner. Infrared findings should be correlated with a thorough visual inspection and other pertinent data to formulate an effective roof maintenance strategy.

For information on infrared training or certification or to obtain a copy of the Guideline for Performing Infrared Inspections of Building Envelopes and Insulated Roofs, contact Infraspection Institute at 609-239-4788.

Traditionally, proper conduct of an infrared inspection of energized electrical switchgear has required that panel covers be opened or removed prior to the infrared inspection. IR transmissive windows and viewports offer an alternative to this practice; however, several important issues must be considered prior to installing windows or viewports.

For many years, safety standards and laws have required that only qualified persons work on or near exposed energized electrical components. As safety standards have evolved, many facilities have sought ways to eliminate exposure of personnel during an IR inspection and the potentially lethal injuries associated with an arc flash.

Currently, a wide variety of commercially available inspection ports and IR transmissive windows are being offered as an alternative to removing panel covers for an infrared inspection. Prior to installing such devices one should bear the following in mind.

• Ascertain spectral response of chosen window to ensure that it is appropriate for use with your imager
• Determine field-of-view for the subject window
• Identify number of windows and positioning to ensure adequate coverage
• Evaluate whether installed viewports will compromise safety by allowing easier access to energized components
• Consult with switchgear manufacturer to ensure that window installation will not void warranty or ratings of switchgear enclosure

Because much of the marketing information for windows is misleading, caution is recommended when considering the installation of windows in switchgear enclosures.

This Tip of the Week was submitted by Vance Cowper, Infraspection Institute Certified Infrared Thermographer #6370. Vance is employed by MCI.

As thermography has gained in popularity, the demand for training services has also increased. Since operator training can have a profound effect on the success of an infrared program, obtaining quality training is of paramount importance.

At present, there are several firms that offer infrared training and certification. While nearly all infrared training firms refer to their training courses by level (1, 2, or 3), there are no standards which dictate the content of any offered course. As a result, training courses can vary widely between firms.

When choosing an infrared training firm, be certain to:

• Examine course curriculum to ensure that it meets one’s needs
• Ensure that course will be germane to all infrared imagers, regardless of age
• Ascertain if Certification is included with course, its expiration date, and renewal fees
• Determine number of years training firm has been in business - not the
  cumulative total of staff years
• Insist that instructors be practicing thermographers with documentable field experience in their area of instruction

Lastly, beware of claims that training is “vendor neutral”. It is impossible for training firms to sell infrared equipment or train for equipment manufacturers without being biased. Firms who train for manufacturers work for manufacturers and cannot provide the unbiased information students deserve. Simply put, no man can serve two masters.

Infraspection Institute has been providing infrared training and certification for infrared thermographers since 1980. Our Level I, II, and III Certified Infrared Thermographer™ training courses meet the training requirements for NDT personnel in accordance with the ASNT document, SNT-TC-1A. All courses are taught by practicing, expert Level III thermographers whose field experience is unsurpassed anywhere in the world. We teach effective, real-world solutions using the latest standards, software and technology. For more information call 609-239-4788 or visit us online at www.infraspection.com.

Spam is that unwanted email that shows up in our email Inboxes on a regular basis. If you are not careful, you may find yourself receiving hundreds of unwanted emails each day. There are a number of actions you can take to limit the amount of unwanted email and preserve valuable time.

Spammers acquire email addresses in various ways. The most insidious is tricking you into confirming your email address. Frequently, the spammer accomplishes this by sending you spam with a message in the text that says something like: “Click here to be removed from our list.”

Of course, the instant you reply, the spammer knows that they have reached a valid email address - yours! You have also just confirmed that you read and respond to email. Ignore the “remove me” choice and just delete the unwanted email

If you use the Out of Office reply feature of your email program, spammers will automatically receive confirmation of your email address when your program responds to their spam by advising them of your absence. If you wish senders to receive a response during your absence, have incoming email routed to a person in your office who can send out a message for you when necessary.

In short, there is no way to prevent spam. However, you can minimize the amount you receive by not confirming your email address to spammers when they send you unwanted solicitations.

This week's Tip submitted by Accolade Group.

Windows are semi-transparent materials placed between an object and an infrared instrument to separate conditioned from unconditioned spaces. When measuring temperatures through a window, it is imperative to know and enter the Transmittance value of the window into your radiometer’s computer to help ensure temperature measurement accuracy.

Because no object is 100% transmissive, infrared windows will always have Transmittance values of less than 1.0. Following the procedure listed below, it is possible to calculate the T value of any window.

Equipment Required:

1. Calibrated imaging radiometer with a computer that allows user to input Reflected Temperature and Emittance values .
2. Blackbody simulator with E > 0.95 heated close to temperature of target to be measured.
3. Window that is semitransparent in the waveband of the imaging radiometer.

Method

1. Place imaging radiometer at desired distance from blackbody simulator.
2. Aim and focus imager on blackbody simulator. Place crosshair on
   center of blackbody simulator.
3. Set imager’s E control to 1.0
4. Measure and compensate for Reflected Temperature.
5. Measure and note apparent temperature of blackbody simulator.
6. Place window directly in front of imaging radiometer’s lens.
7. Without moving imager, adjust E control until observed temperature matches value obtained in Step 5 above. The displayed E value is the Transmittance percentage for this window with the subject imaging radiometer. For greater accuracy, repeat above a minimum of three times and average results.

The above procedure is described in detail in the Guideline for Measuring and Compensating for Reflected Temperature, Emittance, & Transmittance available from Infraspection Institute. For more information or to place an order, call 609-239-4788 or visit us online at www.infraspection.com.

On February 11, 2004, the sixth edition of NFPA 70E Standard for Electrical Safety in the Workplace became available superceding all previous editions. In addition to a new look, layout, and title, the latest edition of NFPA 70E contains several important changes including the requirement for an energized electrical work permit.

The 2004 edition of NFPA 70E requires an Energized Electrical Work Permit if live parts are not placed in an electrically safe work condition. NFPA 70E requires that the permit shall include, but not be limited to, the following items:

• Description of the circuit and equipment to be worked on and their location
• Justification for why the work must be performed in an energized condition
• Description of the safe work practices to be employed
• Results of the shock hazard analysis
• Determination of shock protection boundaries
• The Flash Protection Boundary
• Necessary Personal Protective Equipment to safely perform the assigned task
• Means employed to restrict the access of unqualified persons from the work area
• Evidence of completion of a job briefing, including a discussion of any job-specific hazards
• Signature(s) of authorized personnel who are approving energized work

Work performed on or near live parts by qualified persons related to tasks such as testing, troubleshooting, voltage measuring, etc., shall be permitted to be performed without an energized electrical work permit, provided appropriate safe work practices and personal protective equipment are used.

Copies of NFPA 70E can be purchased by calling the National Fire Protection Association at 1-800-344-3555 or online at: www.nfpa.org.

Personal Protective Equipment, including fire resistant clothing, has long been specified by NFPA 70E. The 2004 edition contains several important changes including a new requirement that workers wear an arc-rated face shield.

The 2004 edition of NFPA 70E requires workers to wear an arc-rated face shield if live parts are not placed in an electrically safe work condition and work is to be performed within the Arc Flash Boundary. This new requirement applies to work having a Hazard/Risk Category 2. Face shields must have a minimum arc rating of 8, with wrap –around guarding to protect not only the face, but also the forehead, ears, and neck. A flash suit hood may be used in place of an arc-rated face shield.

For electrical systems that are rated at 600 volts or less, NFPA 70E defines the Arc Flash Boundary as a minimum of 4.0 feet for systems having an available bolted fault current of 50kA. This Arc Flash Boundary distance increases as available fault current and/or clearing times increase and may be calculated using the formulae found in Article 130.3 (A).

Copies of NFPA 70E can be purchased by calling the National Fire Protection Association at 1-800-344-3555 or online at: www.nfpa.org.

Many companies that contract thermographic inspections are usually provided with a technical report clearly identifying areas and conditions that need attention. From the information contained in the report, maintenance personnel investigate suspect areas and make appropriate repairs.

Once corrective actions have been completed, it is extremely important to have the thermographer return to reinspect suspect areas to ensure that the original discrepancies have been properly repaired. One professional infrared testing company reported as many as 80% of exceptions were still present after repairs had reportedly been made. In this case, the follow-up inspection was actually more important than the original inspection.

The follow up inspection is also a good time to have the thermographer inspect equipment that may have been off line or not under load at the time of the initial infrared inspection.

Infrared thermography has the highest return on investment for all of the PPM technologies. It has been calculated at about ten dollars saved for every dollar invested. So, it is important to reinspect after repairs. A follow up infrared inspection can make a fair PPM program into an exceptional PPM program.

This Tip of the Week was submitted by Erich Black, of Black & Associates, 15210 Priceville Road, Sparks, MD  21152. Erich may be contacted at 410.472.2416 or via e-mail. Visit their web site.

Perhaps the most common application for infrared thermography is PdM inspections of electrical distribution systems. However, in focusing on the inspection, many overlook the critical step of properly preparing for the inspection.

Proper planning prevents poor performance. For IR inspections of electrical distribution systems, this planning should begin well in advance of the inspection. The following are some of the not-so-obvious considerations that should be part of every inspection.

• Performance standard(s) or Guidelines to be followed
• Safety standards and rules applicable to the work areas
• Thermographer and qualified assistant(s) should be trained as qualified persons as defined by NFPA and OSHA standards
• Necessary Personal Protective Equipment including fire resistant clothing
• Provisions for First Aid and CPR
• Pre-job safety briefing prior to the commencement of the inspection

Lastly, infrared inspections should only be performed by experienced, certified infrared thermographers who thoroughly understand the theory and operation of electrical distribution systems. Properly planning for your next infrared inspection can provide for a safer and more efficient inspection.

For more information on thermographer training and certification, or to order a copy of the Guidelines for Infrared Inspections of Electrical and Mechanical Equipment, call us at 609-239-4788 or visit us online at: www.infraspection.com

During the past twenty years, professionalism has been a concern frequently discussed among practicing thermographers. Few realize that true professionalism begins with the individual and is the responsibility of every member of the infrared community.

Frequently it seems that thermography has matured more rapidly than some of its participants. The infrared industry has more than a few who seem to go out of their way to accentuate the negative either by word or by deed, often in a sensational fashion. Unfortunately, this behavior reflects on the thermographic community as a whole.

Because professionalism is determined by those who practice thermography, it is incumbent upon every infrared professional to define our technology on a daily basis through their actions. If you are a practicing thermographer the following are some ways you can help to enhance the image of our profession.

• Always promote thermography in an honest and positive manner
• Do not offer derogatory or negative comments about a competitor
• Always use equipment appropriate for the subject inspection
• Make sure that your formal training is current and the highest level you can achieve
• Always work within the limits of your training and experience
• Whenever possible, adhere to published Standards or Guidelines

Lastly, when promoting your services or products, do so only in an honest and forthright manner. We invite infrared professionals to act responsibly and with integrity by adhering to the simple concepts outlined herein. Doing so will maintain and enhance the professional image of our technology.

We’ve all heard the phrase, “Put the horse before the cart.” When it comes to thermography, many people put the cart in front of the proverbial horse by buying infrared equipment before obtaining proper training.

Purchasing the correct imager is a challenge for many reasons: initial purchase price can be costly, no imager is capable of performing all applications, imager performance varies widely, and available specifications are frequently exaggerated.

Further compounding this challenge is that many manufacturers offer “free training courses” as sales incentives to purchasers of new equipment. Frequently these free courses are taught by inexperienced/unqualified instructors, are introductory in nature, and are designed as operator courses for the subject equipment omitting important theory or applications. Because these courses are taught after equipment is delivered, inexperienced purchasers lack the knowledge required to make an informed decision when selecting new equipment.

In order to properly select and specify infrared equipment, buyers should put the horse before the cart by receiving quality certification training from an independent institute prior to equipment purchase. For new users, training should include infrared theory and heat transfer concepts, equipment selection and operation, image capture and analysis, standards compliance, applications-specific inspection techniques, documentation of findings, and temperature measurement techniques.

Infraspection Institute offers Level I, II, and III training and certification for thermographers worldwide. Our cutting-edge infrared training courses are taught by highly-experienced thermographers in a friendly, relaxed atmosphere without marketing hype. For more information call 609-239-4788 or visit us at www.infraspection.com.

As individuals, most of us can appreciate the cooling effects of a breeze on a hot summer day. As thermographers, wind represents a greater technical challenge in the form of a potential error source when measuring temperatures radiometrically.

As wind moves across the surface of an object, convective heat transfer occurs. In general, wind will either cool a warm target or warm a cool target. The rate of convective heat transfer will primarily depend upon: velocity of the wind, temperature differential between object and wind, and surface film coefficient of the object.

Wind can significantly alter the temperature of an object while the windy condition is present. Frequently, the effects of wind may remain for a significant period of time after the wind has stopped and the object has returned to its normal temperature.

Because radiometric equipment cannot compensate for the effects of wind on an object, it is best to avoid wind when measuring object temperatures. To eliminate wind as an error source:

• Wait until wind stops
• Temporarily shield target from wind
• Measure downwind side of target provided that object is sufficiently large

Always allow sufficient time for target to return to normal temperature once wind has been eliminated. If it is not possible to avoid wind, one should report wind velocity and direction when recording image data.

Lastly, thermographers should resist any temptation to apply ‘Wind Chill Charts’ to correcting for the effects of wind. Wind Chill charts have been designed to estimate the net effect of wind and ambient temperature on exposed human flesh and are not applicable to inanimate or industrial objects.

Infrared inspections can be a valuable tool for detecting problems within electrical distribution systems. Understanding when and where to utilize thermography is key to obtaining optimum benefit.

Infrared inspections can detect and document evidence of loose/deteriorated connections, overloaded circuits, imbalanced loads, harmonics, and defective equipment. In some cases, infrared inspections can detect evidence of problems that may be overlooked by traditional electrical testing. Infrared inspections should be used to supplement, but not replace, regular preventive maintenance.

When setting up an IR inspection program for an electrical distribution system, keep the following in mind:

• Inspections should be performed at least annually
• Inspections should be conducted with the electrical system under normal load
• Inspections require clear line-of-sight to inspected components
• When possible, IR inspections should be performed 4 to 6 weeks in advance of PM shutdown to allow time to order necessary parts
• Exceptions should be reinspected after repair to ensure that repairs were effective
• All new/retrofitted equipment should be inspected within 24 hours of installation
• All findings should be documented in writing in accordance with the Guideline for Infrared Inspection of Electrical and Mechanical Systems

Lastly, infrared inspections should only be performed by certified infrared thermographers who are thoroughly familiar with the system(s) being inspected.

For more information on thermographer training and certification or to obtain a copy of the Guideline for Infrared Inspection of Electrical and Mechanical Systems, contact Infraspection Institute at 609-239-4788 or visit us online at www.infraspection.com.

As infrared technology has advanced, radiometers have become a common tool for many maintenance technicians and mechanics. Although radiometers are relatively easy to use, there are several important factors that influence the accuracy of a radiometer’s readings. Infrared radiometers offer several advantages when it comes to temperature measurements.

Measurements are non-contact, non-destructive and can be obtained quickly. Unfortunately, radiometers are not self-diagnostic and cannot warn the operator of erroneous readings. The following are some simple tips that can help to ensure accurate infrared temperature measurements.

• Target should be stationary and at a stable temperature with a dry surface
• Radiometer lens should be clean and free from obstructions
• Radiometer batteries should be fully charged
• IR temperature measurements should be made perpendicular to target
• IR radiometer should be operated at a distance to ensure that spot measurement size is smaller than the target
• Accurate emissivity and reflected temperature values should be input into the radiometer’s computer.

Whenever possible, infrared readings should be correlated with known temperature values. If a discrepancy is observed, it could be due to a procedural error in measurement or the radiometer may require calibration.

For more information on infrared temperature measurement, or to obtain information on thermographer training and certification, contact Infraspection Institute at 609-239-4788 or visit us online at www.infraspection.com.

Many infrared inspection programs include motor control circuits but overlook the motor itself. Evidence of several conditions which can lead to premature motor failure can be detected with a thermal imager. The following are suggestions for thermographically inspecting motors.

• With cover removed, inspect electrical connections at the motor junction box. This should be done in conjunction with the regularly scheduled inspection of the facility’s electrical system.
• Inspect motor casing for localized hotspots which may be indicative of short circuits within motor windings
• Qualitatively compare individual motors to similar motors under similar load
• 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.

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. Additionally, infrared can detect evidence of misalignment at lower thresholds than those detectable by vibration analysis and motor current signature analysis.

Lastly, infrared inspections of motor bearings and stator should be performed monthly by experienced, certified infrared thermographers who thoroughly understand the theory and operation of electric motors.

In regions with older infrastructure, sewer system integrity is often a primary concern. Under the right conditions, thermography can often detect sewer leaks or voids surrounding the system that can lead to sinkholes.

In the case of sewer systems, thermal imaging is usually employed during evening hours after a sunny day. During the inspection, the thermal imager is maneuvered over the pathway of the subject sewer system looking for unusual thermal patterns. The imager may be operated on foot, from a motor vehicle or an aircraft.

Sewer system defects which may be detectable include leaks to surrounding soil and voids around sewer piping. The detectability of these defects will be largely dependent upon:

• Depth of sewer system
• Amount of loss
• Pipe construction
• Soil type and ground cover

One should be aware that a negative finding does not necessarily mean defects are not present; they simply may not be detectable by thermal imaging. Conversely, positive findings can be caused by conditions other than leaks. Therefore, it will be necessary to verify all thermal data by visual inspection.

The topic of infrared inspections of buried piping systems is covered in depth in our Level I Certified Infrared Thermographer™ classes. For more info on training and class dates, please call or visit us online at: www.infraspection.com.

Did you know that an automobile can be used to gauge solar loading? Under the correct conditions, a parked car can serve as a cheap, but effective, pyranometer.

Many types of infrared inspections rely on solar loading to heat the target so that infrared imaging may be performed successfully. Applications include, but are not limited to, low slope roof inspections, concrete bridge decks, storage vessel levels and latent moisture within building sidewalls. Ensuring that enough solar loading has occurred is imperative to collecting good data.

Good solar loading conditions are easy to recognize – long days with bright sunny skies, low humidity and no wind. More tricky is being able to determine if less than optimal conditions are allowing for appreciable solar gain.

A time tested method for gauging solar loading is to check the interior of a parked automobile. With the engine stopped and the windows and doors closed, allow the vehicle to sit in the sun for up to an hour. Immediately upon opening the door, check to see if the vehicle interior has exceeded outdoor ambient temperature. If a noticeable difference is not detected, feel the dashboard to see if it has warmed. If not, it is likely that appreciable solar loading has not occurred and it may be best to reschedule your solar driven inspection for another day.

Most problems on electrical systems are preceded by a change in its thermal characteristics and temperature, whether hotter or cooler. A trained and experienced thermographer is able to identify and analyze those anomalies prior to costly failures occurring.

Thermography is one of the tools used by the Bruce Power Predictive Maintenance group which was created last year. Four thermographers at Bruce B and two at Bruce A started to perform thermography inspections of electrical equipment. Baseline inspections have been completed to this point on the most critical equipment. An example of a recent successful deployment of thermography is detailed here.

At Bruce A, Len Bridge and Bob Forrest performed a thermography inspection of the Unit 4 main output transformer. Elevated bushing temperatures revealed an imminent problem. Inspection results successfully confirmed that the cooler was plugged due to rust buildup. The pictures describe the story.

As the popularity of infrared transmissive switchgear windows increases, many have begun to question how much windows attenuate the observed infrared data. With no standards governing the manufacture of switchgear windows, the answer can vary depending upon the make and model of the window and the selected infrared equipment.

Infrared transmissive windows have seen increasing popularity as an alternative to opening electrical cabinets for infrared inspections. These windows typically contain an IR transmissive material supported in a metal frame and are permanently installed at strategic locations in the switchgear enclosure. During the infrared inspection the camera lens is placed against the window to inspect electrical components without having to open the subject enclosure.

As no material on earth is 100% transmissive to infrared energy, all infrared windows will qualitatively and quantitatively attenuate the infrared energy passing through the window. While it is useful to know the transmittance of the window’s optical material, there are other important factors to be considered. It should be noted that there is no way to compensate for any of the common error sources listed below.

• Many IR windows have optics far smaller than IR imager lenses vastly reducing the infrared energy reaching the detector
• Switchgear windows that become dirty over time attenuate IR energy
• Some switchgear windows are wavelength specific and will react differently according to imager selected
• Depending upon cabinet depth, it may not be possible to obtain clear focus for the subject components

Prior to installing switchgear windows, it is imperative to understand their applications and limitations. For more information on calculating the transmissivity of switchgear windows, consult the Guideline for Measuring and Compensating for Reflected Temperature, Emittance & Transmittance available from Infraspection Institute.

When performing an infrared inspection of low slope roofing systems, invasive testing is necessary to confirm the composition and condition of roofing system components. As asphalt and coal tar are incompatible materials, it is imperative to use the correct bitumen to ensure the long term integrity of repaired test sites.

Asphalt and coal tar are hydrocarbon materials commonly used for built-up roofing. While both share a common use in roofing, they are very different in their chemical composition. Asphalt is a petroleum distillate and a byproduct of crude oil refining. Coal tar is a bituminous product that is largely insoluble in petroleum distillates.

Odor is one way to differentiate between asphalt and coal tar – tar has a distinctive creosote smell. A more reliable method is to test bitumen solubility in mineral spirits. This simple test can be performed as follows:

• Obtain a small sample (pea size nugget) from the subject roof
• Soak sample in a small amount of mineral spirits in an empty glass container such as a baby food jar
• Stir sample gently for about one minute and note results

If sample dissolves to black liquid – sample is asphalt; if sample remains intact and/or colors mineral spirits to a yellow/green color, sample is coal tar.

Once bitumen type has been determined, one should use appropriate repair materials along with the same bitumen as indicated by the above test. Doing so will help to ensure the long term integrity of repaired test sites.

For those who work near exposed, energized electrical equipment, a popular question is, “How much arc flash protection do I need?” This week’s Tip focuses on two ways to answer this question.

NFPA 70E mandates that Fire Resistant Clothing be worn whenever an employee is working within the Arc Flash Boundary. For equipment rated at 600 volts or less, the Flash Protection Boundary is 4.0 feet; this distance increases proportionally with available energy levels. The selected flash protection must provide thermal protection against the potential heat generated should an arc flash occur.

The amount of heat associated with an arc flash is dependent upon the amount of energy available and the distance from the fault. The amount of energy available is dependent upon available fault current and clearing time for the fault. NFPA 70E provides two methods for determining how much FRC is needed.

The first method involves utilizing an engineering calculation to determine the amount of energy available for subject components. Employing this formula usually requires the skills of an electrical engineer and specific information about the subject equipment including voltage, amperage and overcurrent protection. Protective clothing is selected based upon the amount of potential heat energy determined from the calculation.

The second method utilizes a table listing electrical equipment and common work tasks. By identifying the work task and the category of subject electrical equipment, one may determine the Hazard/Risk Category associated with a specific task. Once the Hazard/Risk Category has been determined, a second table is utilized to determine the required PPE for the particular Hazard/Risk Category.

Among thermographers, few things can cause an acute stomach ache like damaged equipment. Damaged equipment is not only costly to repair, but may also interrupt an inspection program while the equipment is being repaired.

With infrared equipment, an ounce of prevention is worth several pounds of cure. Fortunately, preventing equipment damage is easy and inexpensive. Some of the best ways to prevent damage are as follows:

• Store IR equipment in hard sided shipping cases that have die cut foam to fit the subject equipment and its accessories
• Keep lens caps on camera and extra lenses while in the storage case
• When not in use, store IR equipment and accessories in a cool, dry place
• When transporting or shipping equipment, utilize extra padding to prevent components from shifting in the carrying case
• When traveling on an aircraft, hand-carry your imager. Be sure to allow extra time when going through airport security and encourage inspectors to be extra careful with your equipment

Lastly, maintain your equipment carrying cases in good working order. Repair or replace defective or worn hardware. If your case should become worn, replace it with a new original or an after-market case suitable to the task. Some shipping cases are guaranteed for life and replacement parts may be available at no charge.

Intrinsically safe test equipment is a requirement for workplaces where combustible gasses may be present. Prior to performing an infrared inspection in such areas, it is important to understand the meaning and importance of this requirement.

Intrinsically safe is a term that applies to test instruments that will not produce sparks or thermal effects capable of igniting a flammable vapor. Intrinsically safe equipment is frequently required in mines, chemical refineries, and in areas where combustible gasses, vapors, or dust may collect. Using instrumentation other than intrinsically safe in these areas could cause a potentially lethal fire or explosion.

Presently, most infrared inspection equipment is not rated as intrinsically safe. Because of this, infrared equipment not rated as intrinsically safe should never be operated in an area where combustible gasses or vapors are present.

In areas where there is a potential of combustible gas accumulation, the area should be sampled for combustible gasses and oxygen content prior to the infrared inspection to ensure that the area is safe to enter. Once area has been deemed safe, the area should be continuously supplied with fresh air and monitored regularly during the inspection.

Currently published industry standards require that core samples be obtained when performing infrared roof moisture surveys. Properly procuring and patching core sample sites can help to maintain watertight integrity of sample sites.

Core sampling a roof involves physically removing a portion of the roof membrane and insulation layers to ascertain the composition and condition of roofing system components. Core samples may be square or round and range from a couple of inches in diameter to a several square feet in size.

The following procedure outlines the steps in sampling and patching 2” diameter core samples on gravel-surfaced, built-up roofing systems.

• Locate sample site on flat portion of roof not subject to ponding
• Spud gravel off membrane for 12” diameter area. Use wire brush to remove dust
• Use core cutter to sample through membrane down to deck. Do not cut through roof deck
• Fill sample hole approximately ¾ full with cold roof mastic compatible with existing roof bitumen
• Install plug made from perlite insulation. Cold mastic should flow up and around plug once it has been seated firmly on roof deck at bottom of hole. Top of plug should be within 1/8” of top of sample hole when plug has been pushed to bottom
• Coat cleared area with roof mastic
• Center 6” diameter disk of 15 lb roofing felt over plug. Firmly press felt down to remove air pockets and fish mouths.
• Apply thin layer of roof mastic over 6” felt
• Center 12” diameter disk of 15 lb roofing felt over plug. Firmly press felt down to remove air pockets and fish mouths
• Apply generous layer of roof mastic over 12” felt. Replace gravel and outline area with spray paint

Prior to sampling, determine if roof is under any warranty that could be voided by sampling. Always obtain permission to perform any invasive testing before you begin.

Infrared thermography is frequently used for condition monitoring of refractory-lined vessels such as boilers, furnaces, reformers, and cat crackers. By inspecting these same vessels during different stages of start-up, one can find problems that may not be detected when the subject vessel is operating at full rates and temperature.

Within refractory-lined vessels, refractory will tend to expand as temperature increases. In a perfect world, there should be no detectable thermal anomalies during low temperature operation but, in fact, you may be able to readily detect refractory problems while the unit is operating at below normal temperatures.

During startup, one may notice that some hot spots will disappear once the vessel has reached normal operating condition. This is because the refractory has expanded and sealed off cracks within the interior of the unit. It is not uncommon to see an exception that has reached near critical temperature to completely disappear or cool to an acceptable limit once the vessel has reached full rates. Hot spots remaining after startup may indicate serious problems and should be closely monitored.

By identifying exceptions at lower operating temperatures, one may better predict where a future problem or failure may occur. For vessels subject to cyclical loading, these same areas are usually the first to deteriorate due to an excessive amount of expansion and contraction.

When used as a quality assurance or condition monitoring tool, infrared thermography can help to avoid unnecessary or unexpected shutdowns thereby saving a facility valuable production time and money.

This Tip of the Week was submitted by:

Sonny James
Thermal Diagnostics Limited
15 Robertson Street
Les Efforts East
San Fernando
Trinidad, West Indies

www.tdlir.homestead.com

Build it and they will come. This romantic notion worked for Kevin Costner in the film, Field of Dreams; however, real life and business are rarely that simple. Once you have built your infrared inspection business, there are time-tested ways to help ensure that customers will come.

Getting prospects to come to your business involves more than setting up shop and hanging out a shingle. In order to thrive, you have to let prospects know that you are open for business and that you are ready to respond to their needs. The following are some of the most effective ways to get your message out to potential customers.

• Have a professional artist design a color brochure that fully describes your capabilities and strengths along with the benefits that customers can expect from your services.
• Engage a website professional to design a website that mirrors your advertising brochure. Whenever possible, choose a domain name that is easy to remember and contains your company name only. Be certain to update your website periodically.
• Network with other professionals that can bring you work through their business activities. Architects, engineers, contractors and consultants can be excellent strategic partners. Once you have established a relationship, you reap the benefit of their sales efforts at no cost.
• Once you have identified prospects within your region, hit the bricks and do some old fashioned selling. In this day of internet selling, email and instant messaging, putting a human face on your company can be worth its weight in gold.

Lastly, advertise your company in an online directory where prospects are likely to visit. At present, IRINFO.ORG receives 250,000 visitors each year, many of whom are looking to hire an infrared professional. Listing your company in our Directory of IR Inspection Companies can mean the difference between working hard or hardly working.

Many animals and even some people are credited with having a sixth sense for knowing or anticipating events before they happen. The benefits of this seemingly supernatural power can be enjoyed by applying a discipline known as situational awareness.

Situational awareness is a technique that has been practiced by pilots and military personnel for several years. Situational awareness is a discipline that requires a person to be constantly aware of his/her surroundings and to constantly anticipate what might happen next. By constantly being aware of what might happen one is better able to plan an appropriate response before an event occurs, thereby avoiding surprises.

With the hazardous environments in which thermographers frequently work, practicing situational awareness make sense. Thermographers can apply the discipline of situational awareness by observing the following:

• Always be aware of your immediate surroundings and the hazards contained therein
• Recognize how the actions of others might affect your situation
• Be aware of weather or environmental conditions that could present a hazard
• Have an emergency response for any situation that could occur
• Know where emergency equipment and communications devices are located
• Identify both primary and secondary evacuation routes for use in case of an emergency

Practicing situational awareness means that you plan for what could go wrong instead of what is likely to go wrong and have preplanned responses for any eventuality. Taking some time to practice situational awareness can vastly improve your personal safety by helping to eliminate surprises and the confusion that goes along with them.

Ever wonder why magicians never reveal their secrets? It's because magic, like most things, is easy once you know the trick. When describing thermography in lay terms, it is easy to over emphasize simplicity and forget the source of the true magic behind thermography – the thermographer.

An infrared inspection system consists of infrared imaging equipment, a thermographer, and the knowledge that he/she possesses. Of these three things, the greatest limiting factor in an infrared inspection system is the thermographer.

In order to be an effective a thermographer, one must be trained in the following:

• Theory and construction of the object or system being inspected
• Infrared theory and heat transfer principles
• Use and operation of infrared imaging equipment
• Non-contact temperature measurement error sources and how to avoid or correct for them
• Site-specific safety requirements and the use of appropriate PPE

In addition to the above, qualified thermographers must also be experienced with inspecting the subject system. When all things are considered, effective thermographers need considerable training and field experience. Making thermography look simple is a true testament to the skills of a professional thermographer.

The next time you hear the dismissive claim that thermography is easy, remember, it is only easy after someone has invested considerable time and effort to learn the art and science of the trade. In a magic show, the magic comes from the magician, not the wand. In thermography, the magic comes from the thermographer.

You’ve probably heard the saying, “You can’t see the forest because of all the trees.” Sometimes thermographers can’t see visible discrepancies for the thermal imagery.

Thermal imaging is a very powerful tool for detecting, displaying and recording thermal patterns across the surface of an object. With the high tech information that thermography provides, it’s often easy to overlook problems that are visually apparent. Taking some time to study your subjects and their surroundings can provide additional information that can aid in your analysis or even discover deficiencies that your thermal imager may not detect.

When performing an infrared inspection, be certain visually inspect targets and their surroundings to:

• ·Note how nearby hot or cold objects may affect the inspected items
• Identify environmental conditions that may adversely affect infrared data
• Ascertain how target characteristics such as emittance will impact infrared analysis
• Detect signs of previous overheating such as discoloration, oxidation or melting
• Correlate visual observations to the displayed thermal image

Lastly, many published standards and specifications require visual inspections be performed simultaneously with thermographic testing. Taking the time to visually inspect your subjects may improve your diagnoses and help to ensure that your inspections are compliant with industry standards.

When performing infrared inspections of branch circuit panels, lighting circuits will often appear warmer than adjacent circuits. If adjacent circuits are lightly loaded, the warmer circuits may be indicative of a normal condition or they may represent a more serious condition.

For electrical panels with single-phase branch circuits, is often quite normal for lighting circuit circuits to appear warmer as they frequently have some of the highest loads within the panel. To confirm this, load readings should be obtained with a true RMS ammeter to determine that the subject breakers are operating within specifications. For long term use, it is recommended that circuits operate at less than 80% of their rated capacity.

If lighting circuit breakers are used as switching devices, they must be rated as Switch Duty. Using non-switch-rated breakers can cause excess wear on the breaker contacts. To determine the integrity of breaker contacts, one should remove the breaker from service and perform a contact resistance test through the breaker with the breaker in the closed position. Such testing should be performed with a digital low resistance ohmmeter.

If lighting circuits have fluorescent fixtures or other solid state devices connected to them, the circuits are likely to contain significant harmonic content. To determine if significant harmonics are present, the subject circuit should be tested with a harmonics analyzer.

In lieu of testing a suspect breaker, you may wish to replace it with a new one and re-image the subject circuit to ascertain if the situation has improved.

One of the most challenging aspects of performing infrared inspections involves directing a qualified assistant in outlining exceptions on the surface of the ground or an insulated roof.

Thermographers who perform infrared inspections of flat roofs or underground piping systems often outline the perimeter of exceptions with spray paint. Directing a qualified assistant to accurately outline exceptions can be both time-consuming and frustrating. The following suggestions can help to speed inspections while preserving coworker relations.

• When using spray paint to mark at ground level, use a spray paint and dispenser designed for the task
• Make sure surfaces to be marked are clean and dry and will not be damaged by spray paint
• Never spray paint where wind may carry paint to unintended surfaces
• Be certain of target before marking – make certain shoes/hands are clear
• Consult Material Safety Data Sheets before using spray paint for any health and usage precautions

When outlining the perimeter of an exception, use a series of dots to outline the most prominent features of the exception. These dots can then be connected with a solid line once their location is deemed satisfactory. Depending upon weather and target conditions, spray painted lines will often show clearly within the thermal image.

To everything there is a season. The same is true for infrared inspection routes within facilities where equipment or systems are operated seasonally.

Traditionally, many facilities perform infrared inspections on an annual basis. While this approach may detect deficiencies within operating systems, systems not under load due to seasonal or operational conditions cannot be effectively inspected.

Examples of seasonally operated equipment include heating/cooling systems, production machinery, and the electrical distribution system. Effective infrared inspections of seasonally operated equipment begin at the planning stages and should include the following:

• Develop an inventory list of equipment to be inspected
• Group seasonally operated equipment into dedicated routes
• Ascertain operating times for subject systems
• Schedule infrared inspections for the beginning of operating season
• Inspect subject systems while under normal load

Be certain to perform a follow up inspection for all detected exceptions once necessary repairs have been completed. As always, remember to observe all necessary safety precautions before, and during the infrared inspection.

Using thermograms to document exceptions is a time-tested common practice in thermography. At times, this practice can be cumbersome and confusing, especially with large structures.

Simply defined, thermograms are two-dimensional hardcopy images that represent the thermal patterns across the surface of an object. For years, thermographers have utilized film or paper to produce records of the imagery provided by their thermal imager. Traditionally, thermograms work well for small objects or for exceptions that are small in size.

Documenting thermal patterns on large structures such as multi-story buildings or flat roofs can prove to be a challenge. This challenge may be further compounded when observed exceptions are large in size. A simple solution to these challenges is to utilize architectural drawings, elevations, or schematics in place of, or in addition to, hardcopy thermograms. When utilizing drawings to document your infrared inspection, keep the following in mind:

• Prior to the infrared inspection, obtain drawings with sufficient detail
• Verify accuracy of drawings with the subject structure
• Be certain to verify site orientation with compass orientation
• During the inspection, mark the size and location of exceptions directly on drawings along with thermogram numbers, where appropriate

Whenever possible, obtain extra sets of drawings to be used as file copies or for field use. When utilized properly, drawings can serve as valuable reference tools enabling one to see "the big picture" that is often not possible with several small thermograms alone.

With the end of the year upon us, we wish to follow in the grand tradition of saving our best for last. In this Tip of the Week, we address some of the most important issues facing predictive maintenance professionals.

With the holiday season in full swing, we invite PdM technologists and thermographers throughout the world to consider the issues of inventory, reliability and communication and offer our best advice as follows:

• Inventory – Take time to reflect on your many blessings such as good health, family and friends.
• Reliability – Set time aside to appreciate having friends and relatives in whom you can confide and trust.
• Communication – Remember to share your feelings with all of the special people in your life by letting them know what they mean to you.

Spreading cheer and holiday spirit is easy; it begins with each of us as we let others know how we feel about them.

As we enjoy this holiday season, we extend a heartfelt Thank You to all of our readers, friends, and associates throughout the world for everything that you do for us all year long.

May your holidays be filled with peace and joy and your New Year with good health and happiness.

~ Jim & Chris Seffrin

In a recent Tip of the Week, we suggested using architectural drawings to supplement, or as a substitute for, thermograms for large structures. Structural blueprints can also be used to reference locations when performing infrared inspections of large physical structures.

Within the blueprint set for any large structure are individual floor plans which usually indicate the location of structural columns. Floor plan drawings are customarily laid out with column rows indicated by letters on one axis and numbers on the other. Using a combination of letters and numbers (A1, B1, etc.) to designate columns enables one to universally reference locations within a structure.

Because columns are permanent, their designations will not change over time and will not be affected by changes in structure usage such as floor layout or office location. When utilizing column line drawings to document your infrared inspection, keep the following in mind:

• Prior to the infrared inspection, obtain drawings with sufficient detail
• Verify accuracy of drawings with the subject structure
• Obtain a separate plan for each subject floor

During the inspection, mark the location of exceptions directly on
drawings along with thermogram numbers, where appropriate

Whenever possible, obtain extra sets of drawings to be used as file copies or for field use. When utilized properly, floor plan drawings can serve as valuable reference tools enabling everyone to “speak the same language” when it comes to properly referencing locations.