Easier Than A, B, C
Tip written by: Infraspection Institute
When performing infrared inspections of electrical distribution systems, many people identify the individual phases of polyphase circuits as A, B, and C; others frequently use 1, 2, and 3.
Confusion can arise with alphabetical or numerical labels particularly when switchgear enclosures are inspected from different perspectives e.g. front versus rear. Further confusion can occur when phase rotation has been modified or changed or, in some cases, mislabelled.
Reference errors can be avoided by using terms that cannot be confused such as Left, Middle, Right OR Upper, Middle, Lower. When using such terms, one should always reference where the image was taken from. For outside power lines references such as Street, Center, and Field may be used to identify phases without confusion.
Using the above simple terms can make your reports easier to understand and help to eliminate confusion when repairs are performed.
Infrared inspection of electrical distribution systems is one of the many applications covered in the Infraspection Institute Level I Certified Infrared Thermographer® training course. For course schedules or to obtain a copy of the Standard for Infrared Inspection of Electrical Systems and Rotating Equipment, visit Infraspection Institute online at www.infraspection.com or call us at 609-239-4788.
January 18, 2021
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Frequency of Infrared Inspections of Electrical Equipment
Tip written by: Infraspection Institute
“How often should electrical systems be thermographically inspected?” Historically, accepted industry practice has recommended that infrared inspections be performed annually; however, site specific conditions may dictate considerably shorter intervals for some equipment or facilities.
According to the 2010 Edition of NFPA 70B Recommended Practice for Electrical Equipment Maintenance, “Routine infrared inspections of energized electrical systems should be performed annually prior to shutdown. More frequent inspections, for example, quarterly or semiannually, should be performed where warranted by loss experience, installation of new electrical equipment, or changes in environmental, operational, or load conditions.”
Semi-annual infrared inspections may also be prudent where unscheduled outages of electrical equipment could pose significant environmental or safety hazards, or result in catastrophic damage to other systems or components.
Because infrared inspections are only effective when electrical system components are energized, it is imperative to perform infrared inspections when subject equipment is operational. For facilities with seasonal equipment such as heating and cooling systems, it may be necessary to schedule infrared inspections on several different days spread throughout the calendar year.
As always, infrared inspections of electrical systems should only be performed by properly trained and certified thermographers following all appropriate safety precautions. For information on thermographer training and certification or to obtain a copy of the Standard for Infrared Inspection of Electrical Systems and Rotating Equipment, contact Infraspection Institute at 609-239-4788 or visit us online at: www.infraspection.com.
To obtain a copy of NFPA 70B, contact the National Fire Protection Association at 1-800-344-3555 or visit them online at: www.nfpa.org.
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January 25, 2021
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The Best Recommendation
Tip written by: Infraspection Institute
As part of their infrared inspection reports, thermographers frequently include exception diagnoses along with recommendations for repair. In this Tip, we offer our suggestion for the only recommendation a thermographer will ever need.
When used as a tool for Preventive/Predictive Maintenance, thermography can detect and document evidence of thermal patterns and temperatures across the surface of an object. The presence of inexplicable thermal anomalies is often indicative of incipient failures within inspected systems and structures. Because thermography alone cannot determine the cause of an exception, other diagnostic tools must be employed to determine the cause of observed exceptions.
Although thermography is inconclusive, thermographers frequently provide opinions as to the cause of exceptions without having the benefit of confirming test information. Such opinions are frequently accompanied by elaborate recommendations for repair. When such observations/recommendations are incorrect, they can cause repair efforts to be misdirected.
Unless a thermographer has performed, or has access to, confirming tests, providing opinions regarding the cause of exceptions and subsequent recommendations for repair is unwise. When confirming test data are unavailable, a prudent thermographer should make only one simple recommendation: “Investigate and perform appropriate repair”.
Generating standards-compliant reports is one of the many topics covered in the Level I Infraspection Institute Certified Infrared Thermographer® training course. For information on thermographer training including course locations and dates, visit us online at www.infraspection.com or call us at 609-239-4788.
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February 1, 2021
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Frostbite & Hypothermia
Tip written by: Infraspection Institute
“Jack Frost nipping at your nose.” These lyrics from a popular Christmas carol evoke romantic visions of winter; however, frostbite and hypothermia are dangerous medical conditions that can present serious safety hazards.
For many, the dead of winter is upon us. Thermographers working outdoors in cold climates can face serious safety challenges due to frostbite and hypothermia. Knowing the symptoms of these conditions and proper treatment is imperative for worker safety.
Frostbite is a severe reaction to cold exposure that can permanently damage its victims. A loss of feeling and a white or pale appearance in fingers, toes, or nose and ear lobes are symptoms of frostbite.
Hypothermia is a condition brought on when the body temperature drops to less than 90 degrees Fahrenheit. Symptoms of hypothermia include uncontrollable shivering, slow speech, memory lapses, frequent stumbling, drowsiness, and exhaustion.
If frostbite or hypothermia is suspected, begin warming the person slowly and seek immediate medical assistance. Warm the person’s trunk first. Use your own body heat to help. Arms and legs should be warmed last because stimulation of the limbs can drive cold blood toward the heart and lead to heart failure. If the person is wet, put them in dry clothing and wrap their entire body in a blanket.
Never give a frostbite or hypothermia victim beverages containing caffeine or alcohol. Caffeine, a stimulant, can cause the heart to beat faster and hasten the effects the cold has on the body. Alcohol, a depressant, can slow the heart and also hasten the ill effects of cold body temperatures.
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February 8, 2021
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Measuring and Compensating for Reflected Temperature – Part 1
Tip written by: Infraspection Institute
Non-contact thermometry provides a means for rapidly measuring object temperatures. To ensure measurement accuracy, all error sources must be considered and properly addressed. With this Tip, we discuss how to measure and compensate for Reflected Temperature using the Reflector Method.
Unlike contact thermometry, infrared temperature measurement is subject to several error sources. While many are familiar with emissivity, another common error source is reflectivity. In order to compensate for errors due to reflections, imaging and non-imaging radiometers have inputs for entering Reflected Temperature. Depending upon the make and model of the instrument, this control may be referred to as TAM, Ambient Temp, Background, or Reflected Temperature.
Since all real world objects have emittance values of less than 1.0, some infrared energy will always be reflected from a measured object’s surface. The Reflected Temperature feature found on radiometers will mathematically compensate for this error source provided that it has been properly set by the operator.
Listed below are the general steps for measuring and compensating for Reflected Temperature when using an imaging radiometer and a diffuse infrared reflector. A diffuse reflector can be made from a crumpled and re-flattened sheet of aluminum foil that has been wrapped around a piece of cardboard.
- Place imager at desired location and distance from object to be measured
- Aim and focus imager
- Place diffuse reflector in front of, and in same plane as, object’s surface
- With imager’s E control set to 1.0, measure apparent temperature of diffuse reflector
- Conduct procedure three times and average results
- Enter averaged value into radiometer’s Reflected Temperature input
When measuring Reflected Temperature, make certain to maintain a safe distance from any hot or energized targets and observe all necessary safety precautions. When entering Reflected Temperature into your radiometer, be sure to access the proper menu as some imagers have inputs for Reflected Temperature as well as ambient air temperature.
The above procedure is described in greater detail in the Standard for Measuring and Compensating for Reflected Temperature Using Infrared Imaging Radiometers. For more information on infrared standards or thermographer training, call 609-239-4788 or visit us online at www.infraspection.com.
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February 15, 2021
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Measuring and Compensating for Reflected Temperature – Part 2
Tip written by: Infraspection Institute
Non-contact thermometry provides a means for rapidly measuring object temperatures. To ensure measurement accuracy, all error sources must be considered and properly addressed. With this Tip, we discuss how to measure and compensate for Reflected Temperature using the Direct Method.
Unlike contact thermometry, infrared temperature measurement is subject to several error sources. While many are familiar with emissivity, another common error source is reflectivity. In order to compensate for errors due to reflections, imaging and non-imaging radiometers have inputs for entering Reflected Temperature. Depending upon the make and model of the instrument, this control may be referred to as TAM, Ambient Temp, Background, or Reflected Temperature.
Since all real world objects have emittance values of less than 1.0, some infrared energy will always be reflected from a measured object’s surface. The Reflected Temperature feature found on radiometers will mathematically compensate for this error source provided that it has been properly set by the operator.
Listed below are the general steps for measuring and compensating for Reflected Temperature when using the Direct Method.
- Place imager at desired location and distance from object to be measured
- Aim and focus imager
- Estimate angle of incidence and angle of reflection
- Position imager pointing away from target & parallel to angle of reflection
- With imager focused and its E control set to 1.0, measure average apparent temperature of scene using either area measurement or isotherm feature
- Conduct procedure three times and average results
- Enter averaged value into radiometer’s Reflected Temperature input
When measuring Reflected Temperature, make certain to maintain a safe distance from any hot or energized targets and observe all necessary safety precautions. When entering Reflected Temperature into your radiometer, be sure to access the proper menu as some imagers have inputs for Reflected Temperature as well as ambient air temperature.
The above procedure is described in greater detail in the Standard for Measuring and Compensating for Reflected Temperature Using Infrared Imaging Radiometers. For more information on infrared standards or thermographer training, call 609-239-4788 or visit us online at www.infraspection.com.
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February 22, 2021
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Infrared Training – Why It Isn’t All the Same
Tip written by: Infraspection Institute
With interest in thermography at an all-time high, more people are seeking training and certification. When comparing infrared course offerings, many mistakenly assume that all training and certification courses are the same.
The greatest limitation in an infrared inspection is the thermographer. Because of this, thermographer training and certification have long been recognized as requirements to help ensure accurate inspections. To this end, several firms offer Level I, II, and III training courses; however, these courses are not equal.
The American Society for Nondestructive Testing document, SNT-TC-1A outlines suggested topics for training and certifying NDT personnel in the Thermal/Infrared Testing Method. Suggested topics range from basic theory and camera operation to advanced thermographic applications. Since these topics are suggestions, companies have wide latitude in compiling course content. Because of this, one should never assume that courses bearing the same name will contain similar content.
When considering any infrared training course, be certain to:
- Review course curriculum carefully to ensure it meets your needs
- Ascertain type of certification provided and its expiration date
- Consider the history of the training firm and its credentials
- Determine if courses are available via Distance Learning
Lastly, beware of training courses offered by equipment manufacturers or “vendor neutral” instructors. Only an independent training firm can offer unbiased opinions with respect to equipment choices.
For over 40 years, Infraspection Institute’s Certified Infrared Thermographer® training courses have set the industry standard for excellence. Students may choose from open enrollment classes or our convenient Distance Learning program. All courses are taught by field-experienced Level III practicing thermographers. For more information or to register for a class, call 609-239-4788 or visit us online at www.infraspection.com.
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Detecting Delamination of Stucco
Tip written by: Infraspection Institute
With aging infrastructure becoming an increasing concern in many communities, more attention is being focused on the maintenance of building facades. Under the right conditions, thermal imaging can detect evidence of delaminated stucco or concrete finishes on the exterior of masonry buildings.
Over time, buildings that utilize concrete stucco for exterior finishes are subject to failure. One of these failures involves the stucco delaminating from its substrate. Delaminated stucco is a serious safety concern as it can cause serious injury to pedestrians should it fall from any significant height.
When concrete stucco delaminates from its substrate, an air pocket is formed between the stucco finish and the substrate. Because this air pocket acts as an insulator, it will change the thermal capacity and/or thermal conductivity in the area of the delamination. Under the correct weather conditions, thermal imaging can detect evidence of delaminated areas.
In order to detect evidence of delaminated areas using thermal imaging, a temperature differential must be present. Typically, infrared inspections of concrete stucco are performed during evening hours following a sunny day. As an alternative, infrared inspections may also be performed during midday under solar loading conditions. Thermal patterns associated with delaminated stucco will generally be amorphous in shape and will typically appear as cold spots during post-sunset inspections or as hot spots during midday inspections.
When performing infrared inspections of concrete stucco finishes, keep the following in mind:
- Subject surfaces should be clean and dry
- Wall surfaces must be heated uniformly. Areas in shadow or shade may not produce accurate data
- IR inspections are qualitative in nature. Compare similar areas to each other noting any inexplicable temperature differences
Once the infrared inspection has been completed, all thermal anomalies should be investigated for cause and appropriate corrective measures taken.
Infrared inspection of building envelopes is one of the many topics covered in all Infraspection Institute Level I training courses. For a class schedule or to register for a Distance Learning course, visit Infraspection Institute online or call us at 609-239-4788.
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A Thermographer’s Magic Marker
Tip suggested by: Randall D. Cain, American Water Company
An age-old challenge for thermographers is the ability to annotate or mark objects to make them easier to identify in recorded imagery. One possible solution is to mark targets with an ink pen with low emittance ink.
Many thermographers have long sought ways to mark targets in such a fashion that numbers or text can clearly be seen with a thermal imager. Over time, some thermographers have used paints with emittances that contrast sharply with the objects being marked. In these cases, text and/or numbers painted on the target are clearly visible within resulting thermal imagery and recorded thermograms.
Recently some thermographers have reported good results in utilizing a Sharpie permanent felt-tip marker in silver color. The low emittance of the metallic ink contrasts markedly with high emittance targets allowing annotations to clearly appear within thermal images. In many cases, the silver ink can also be clearly seen in daylight images as well. An example can be seen below.
One should be aware that Sharpie markers are permanent unless the ink is applied to a removable material such as tape or labels affixed to the target. Prior to marking any target, be certain it is safe to do so and that marking will not permanently damage the target.
For more information on thermographer training and certification or to obtain a copy of the Standard for Infrared Inspection of Electrical Systems and Rotating Equipment, call Infraspection Institute at 609-239-4788 or visit us online at wwww.infraspection.com.
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Measurement Accuracy Specifications
Tip written by: Infraspection Institute
“A man’s got to know his limitations.” Clint Eastwood popularized this quote in a 1972 film; this sage observation can also be applied to infrared equipment.
When stating the potential accuracy of infrared thermometers, many manufacturers state radiometer accuracy as “± 2%”. The significance of this specification is often poorly understood causing many to overestimate the accuracy of non-contact temperature measurements.
An accuracy statement of “± 2%” is actually an abbreviated statement. The full statement is “± 2% of target temperature or 2º C, whichever is greater”. The full statement is required since measurement accuracy generally decreases with lower temperature targets. Furthermore, an accuracy of “± 2%” would place accuracy at 0% when measuring targets operating at 0º!
When considering an accuracy statement, it is also important to note that manufacturers derive accuracy specs under laboratory conditions using high-emittance, blackbody simulators in a controlled environment. As a result, manufacturers derive accuracy specs under “best case” conditions which may not be possible to duplicate in a given work environment.
To help ensure measurement accuracy, be certain to:
- Always measure perpendicular to target
- Correctly set radiometer inputs for emittance, reflected temperature, distance and humidity
- Ensure target size is adequate for subject radiometer’s spot measurement size
- Temporarily modifying low E targets can help to improve measurement accuracy
Lastly, real-world challenges can create situations where it is not possible to measure temperatures to the accuracy level promised by an instrument’s spec sheet. These challenges include, but are not limited to, hot or cold ambient temperatures, and the use of different lenses or filters. Whenever accurate infrared temperature measurement is not possible, one should consider using contact thermometry instead.
Infrared imager selection and operation are two of the many topics covered in the Level I Infraspection Institute Certified Infrared Thermographer® training course. For information on our open enrollment or Distance Learning courses, please visit us online at www.infraspection.com or call us at 609-239-4788.
Inductive Heating Hotspots
Tip written by: Infraspection Institute
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.
Infrared inspection of electrical distribution systems is one of the many topics covered in the Level I Infraspection Institute Certified Infrared Thermographer® training course. For information on thermographer training or to obtain a copy of the Standard for Infrared Inspection of Electrical Systems & Rotating Equipment, visit us online at: www.infraspection.com or call us at 609-239-4788.
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Maintaining Situational Awareness
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.
Thermographer safety is one of the many topics covered in the Infraspection Institute Level I Certified Infrared Thermographer® training course. For more information on class locations or our Distance Learning program, visit www.infraspection.com or call 609-239-4788.
Checking IR Equipment Calibration
Tip written by: Infraspection Institute
Equipment calibration can have a significant impact on the accuracy of infrared temperature measurement. In this Tip we discuss a simple technique for checking the accuracy of imaging and non-imaging radiometers.
Infrared radiometers must be within calibration in order to accurately measure temperatures. Traditionally, thermographers periodically send their equipment to the manufacturer for calibration. For some, this process can take several weeks and can be rather expensive. As an alternative, savvy thermographers can check the calibration of their instrument quickly and easily using some commonly available items.
In order to check infrared radiometer calibration, you will need at least two targets each with a known temperature and emittance. A simple solution is to use a container of ice water and a container of boiling water with a coupon of Scotch PVC electrical tape affixed to the container’s exterior surface. The size of both targets must exceed the spot measurement size of the instrument being calibrated. Container temperatures may be ascertained with a thermometer, thermocouple or contact radiometer.
Once targets have been prepared, use the following procedure:
- Turn radiometer on and allow it to stabilize to room temperature
- Set radiometer perpendicular to target surface
- If possible, set radiometer inputs for distance, humidity & air temperature
- Aim, focus and calculate Reflected Temperature
- Set radiometer emittance control. Scotch 191 tape = 0.97 LW or SW. Ice = 0.98 LW; 0.93 SW
- Using subject radiometer, measure temperature of target. For ice water, measure temperature of ice cubes. For hot water container, measure tape coupon.
- Compare radiometer’s value with contact temperature reading for each target to ensure that radiometer is within spec
A heated blackbody simulator can be used to check instrument calibration at higher temperatures. Because radiometer calibration is not user-adjustable, it will be necessary to return it to the manufacturer should you find your instrument is out of spec.
Verifying infrared equipment calibration is specifically covered within Infraspection Institute’s online short course, How to Check Infrared Equipment Calibration. Available 24 hours per day, this 27 minute course focuses on the simple, yet effective techniques for calibrating infrared equipment. The techniques demonstrated are compliant with accepted industry practice and ISO standards. For more information or to register, please visit: https://www.infraspection.com/product/successiries-108/.
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Infrared Inspections of Roofs Containing Foam Insulation
Tip written by: Infraspection Institute
You can’t believe everything you hear. This can be especially true when it comes to performing infrared inspections on flat roofs that contain closed cell foam insulation.
Closed cell foam generically describes several insulation materials commonly found in low slope or flat roofs. Typical materials include urethane foam, isocyanurate foam and, in some cases, cellular glass. Closed cell foam insulations typically offer good R value, are dimensionally stable, and can be used with a wide variety of roofing materials.
Another characteristic of closed cell foam insulations is that they are water resistant. This characteristic, however, only applies to short term exposure to water. When installed in a roofing system and exposed to water for extended periods of time, the cells tend to break down permitting the insulation to become quite absorbent. When this occurs, foam insulation can absorb large quantities of moisture and will exhibit the type of thermal patterns typically associated with absorbent insulations.
Over the years, many have claimed that infrared inspections of closed cell foam roofs are ineffective due to foam’s low absorbency. The thermal image below clearly shows the extent of water damage in a roof constructed with foam insulation.
Note the solid thermal pattern typical of absorbent insulation.
Thermogram provided by Jersey Infrared Consultants
Initially, thermal patterns associated with latent moisture in roofs containing foam insulation will exhibit ‘picture frame’ signatures. These thermal patterns are due to water collecting at the perimeter of individual boards. As time progresses and the foam loses its water resistance, insulation boards will begin to exhibit the same type of thermal signatures exhibited by wet, absorbent insulations such as wood or glass fiber.
Infrared inspections of flat roofs is one of the many applications covered in the Infraspection Institute Level I Certified Infrared Thermographer® training course. For course schedules or to obtain a copy of the Standard for Infrared Inspection of Insulated Roofs, visit Infraspection Institute online or call us at 609-239-4788.
