Preventing a Transformer Fireworks Display
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 gases 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.
Infrared inspections of electrical distribution systems is a topic covered in all Infraspection Institute Level I training courses. For course locations and dates or information on our Distance Learning courses, visit infraspection.com or call us at 609-239-4788.
IR Inspections for Sewer Systems
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® training course. For more information on class locations or our Distance Learning program, visit www.infraspection.com or call 609-239-4788.
Heat Stress & the Human Body
Tip written by: Infraspection Institute
For many, the peak of Summer brings high temperatures to the workplace. For others, high temperatures in the workplace are an everyday occurrence. Understanding heat stress and its attendant safety challenges is crucial for those working in hot environments.
What is heat stress?
Heat stress is a physical hazard. It is caused by environmental conditions and results in the breakdown of the human thermal regulating system.
What are the symptoms of heat stress?
There are various degrees of heat stress. Each has its own unique symptoms. The most common form of heat stress is heat exhaustion. Symptoms of heat exhaustion include dizziness, confusion, headaches, upset stomach, weakness, decreased urine output, dark-colored urine, fainting, and pale clammy skin.
What do I do if I think I am experiencing some form of heat stress?
Act immediately –
- Advise a co-worker that you do not feel well
- Move to an area away from the hot environment
- Seek shade and cooler temperatures
- Drink water (1 – 8 oz. cup every 15 minutes) unless sick to the stomach
- Have someone stay with you until you feel better
What should I think about before working in a hot environment?
Before working in a hot environment, consider the type of work to be performed, duration of time to be spent in hot areas, level of physical activity, and other nearby hazards. Always use appropriate PPE and work together as a team.
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Inspecting Service Entrance Cables
When performing infrared inspections of electrical systems, many thermographers tend to focus their attention on outdoor substations and overhead electric lines. Unexpected failures can occur when service entrance cables are overlooked.
Service entrance cables provide a critical link between outdoor electric supply and a building’s indoor electrical equipment. Like other parts of the electrical system, these conductors are subject to loose or deteriorated connections which can cause unexpected interruptions in electrical power. Fortunately, such loose connections can often be detected with a thermal imager.
When inspecting service entrance cables, one should bear the following in mind:
- Prior to inspection, ascertain that service cables are under adequate load
- When possible, inspect cable connections at both ends. Emissivity issues aside, in most cases connections should be the same temperature as cable conductors
- On long cable runs, be certain to inspect any inline splices for hotspots
- To avoid the effects of solar loading, inspect cable assemblies early in the morning, on a cloudy day or at night
Because it is impossible to predict time to failure based upon temperature, inexplicable temperature rises should be investigated for cause as soon as possible. Doing so can help to avoid unexpected downtime and improve the reliability of a facility’s electrical distribution system.
Infrared inspection of electrical 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.
IR Inspections of Smooth Surfaced Roofs
Tip written by: Infraspection Institute
Having the right tool for the job is often essential for success. When performing infrared inspections of smooth-surfaced roofs, a short wave thermal imager can significantly outperform a long wave imager.
Smooth-surfaced roofs, both single-ply and built-up, can present significant challenges during an infrared inspection due to reflectivity of the roof membrane. Should reflectance be sufficiently high, areas of latent moisture may be undetectable to a thermal imager.
Most infrared inspections of flat or low slope roofing systems are conducted at night by walking across the roof surface using a handheld thermal imager. This technique often results in a relatively shallow viewing angle thereby lowering the emittance of the subject roof membrane.
Depending upon site conditions and roof materials, roof membranes can appear to be as reflective as polished metal surfaces. Membrane reflectivity will be especially noticeable on cool, clear nights that permit the cold night sky to be reflected from the roof surface. It will also be significant on roofs that have been coated with aluminum paint.
To this day, the most practical way to deal with the reflectivity of smooth roof membranes is to utilize a thermal imager with short wave (2 to 5.6 micron) spectral response. This will help to eliminate reflections from the roof and can significantly increase inspection accuracy. Although long wave imagers can be used for smooth membranes, they can significantly understate the size of moisture-damaged areas or miss them entirely.
Infrared inspections of low slope roofs is one of the many topics covered in the Level I Infraspection Institute Certified Infrared Thermographer® training course. For information on thermographer training and certification, visit us online at www.infraspection.com or call us at 609-239-4788.
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The Problem with Solar Loading
Tip written by: Infraspection Institute
Everyone who has performed infrared inspections outdoors on sunny days is familiar with the problem of solar reflections. Compensating for solar reflections is usually accomplished by repositioning the thermal imager to change the viewing angle to eliminate the reflection. For objects exposed to strong sunlight, a more insidious problem can occur in the form of solar loading.
The concept of solar loading is familiar to everyone: objects exposed to the Sun will heat up. In general, dark colored objects absorb the most solar energy and heat faster than light colored objects. If an object absorbs enough heat from the Sun, significant thermal anomalies may be hidden and go undetected.
As there is no way to compensate or correct for solar loading, the most prudent course of action is avoidance. Solar loading can be avoided by imaging on cloudy days, at night, or early in the morning. Solar loading can also be overcome by shading an exposed target and waiting for the object’s temperature to return to normal.
Identifying and overcoming environmental error sources such as solar loading is one of the many topics covered in depth within the Infraspection Institute Level I Certified Infrared Thermographer® training course. For more information on course dates or to register for a course, call 609-239-4788 or visit Infraspection Institute online.
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Temperature Limits for Drive Belts
Tip written by: Infraspection Institute
Temperature is frequently used to gauge the condition of motors and power transmission equipment. In this Tip, we discuss the effect of heat on flexible drive belts and temperature limits for them.
Drive belts are an integral component on many types of machines. Despite the critical role they play in machine operation, V type drive belts tend to be out-of-sight and out-of-mind until they fail. In most installations, belt temperature largely influences the life of installed V belts.
As a rule of thumb, properly applied and maintained belts should not exceed 140º F (60º C), assuming an ambient temperature of less than 110º F (43º C). It should be noted that belt life can be greatly reduced by higher operating temperature. In fact, for every 18 F (10 C) increase in belt temperature, belt life is cut in half.
There are many factors that contribute to high belt operating temperature including, but not limited to: ambient air temperature, machine design, installation, alignment, and belt tension. Overheating belts can be readily detected with an infrared imager. Once detected, overheating belts should be investigated for cause and proper corrective measures undertaken as soon as possible. Doing so can help prevent unscheduled downtime and may prolong belt life.
Temperature limits for mechanical equipment is one of the many topics covered in the Infraspection Institute Level II Certified Infrared Thermographer® training course. Classes are held regularly throughout the year and are also available through our web-based Distance Learning Program. For more information, please call 609-239-4788 or visit www.infraspection.com.
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How Much Certification Do You Need
Tip written by: Infraspection Institute
Certification and levels thereof are one of the most frequently discussed issues in thermography. With few standards addressing certification, purchasers of infrared inspection services and thermographers often ask, “How much certification is necessary?”
Due to a variety of definitions, certification can have different meanings. As it is used in thermography, certification generally means, “to declare something to be true and/or to attest by issuing a certificate to.”
The American Society for Nondestructive Testing document, SNT-TC-1A provides suggested curricula and experience for under the Thermal/Infrared test method. Recommended curricula and the classroom hours are listed below; these should be modified to meet an employer’s needs.
In short, it is up to an employer to determine his/her client’s needs for and to set certification requirements accordingly.
Taken at face value, certification generally indicates one’s level of formal training. This training, combined with experience and knowledge of the system or structure being inspected determine a thermographer’s qualifications.
In a larger sense, certification is a measure of a thermographer’s professional qualifications. It is therefore incumbent on the professional thermographer to achieve the highest level of certification possible. The rewards for doing so are both personal and professional and can provide significant financial and competitive advantages.
Infraspection Institute has been training and certifying professional infrared thermographers since 1980. Our Level I, II, and III Certified Infrared Thermographer® training courses are fully compliant with ASNT and industry standards. Students may choose from open-enrollment and convenient web-based Distance Learning Courses. 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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Combining IR & Ultrasound for Steam Trap Testing
In order to increase the accuracy of thermographic inspections of steam traps, contact ultrasonic testing should be used as well as infrared imaging. Contact ultrasonics are much more sensitive to trap failures than temperature measurement alone.
Over time, two different non-destructive technologies have been employed to test steam systems – contact ultrasonics and temperature measurement. Used individually, each of these techniques has limitations that can lead to false positive and/or false negative results. Combining temperature measurement with ultrasound can result in a highly accurate test method by following a few simple steps:
- Measure trap inlet to ensure that temperature is above 212º F. If trap inlet is below 212º F, ascertain why steam is not reaching trap
- Listen to the trap outlet with contact probe of ultrasonic unit. Continuous hissing or rushing sounds usually indicate a failed trap
- Ascertain that trap is cycling periodically. Frequent cycling may be caused by an undersized or worn trap
- Tag defective traps and document in a written report
- Re-test defective traps after repair to ensure the effectiveness of repairs
While it takes some practice to become proficient with ultrasonic testing, the increased accuracy is worth the effort. Lastly, always be sure to follow appropriate safety precautions especially when working with high pressure steam or when using ladders or lift equipment.
Infrared inspection of steam traps 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.
September 7, 2020
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Infrared Inspections of Arc Fault Circuit Interrupters
Tip written by: Infraspection Institute
Excess heating is often a sure sign of defective electrical equipment; however, the absence of heat can also be a sign of component failure. In this Tip, we demonstrate how thermal imaging may be used to detect defective Arc Fault Circuit Interrupters.
An Arc Fault Circuit Interrupter (AFCI) is an advanced type of electrical circuit breaker that automatically opens a circuit when it detects a dangerous electrical arc on the circuit it protects. Designed to help prevent electrical fires, an AFCI can sense between electrical arcs caused by defective equipment versus those associated with the normal operation of devices such as light switches.
In order to monitor for dangerous electrical arcing on a circuit, AFCI devices have electronic circuitry built into them. This circuitry can cause the body of the AFCI to run several degrees warmer than ambient temperature. Depending upon the settings of your thermal imager, these devices may show a marked contrast to their surroundings.
When thermographically inspecting AFCI devices, be sure to inspect the line and load side connections at the AFCI device as well as the neutral bus bar connection for the subject breaker. Should you find an AFCI device that is operating close to ambient temperature, it is likely that the internal circuitry has failed making the device incapable of protecting against arc faults. Such devices should be further tested and replaced if they are found to be defective.
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.
September 14, 2020
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Standards for Infrared Thermography
Tip written by: Infraspection Institute
As thermography has matured, standards have appeared governing the conduct of infrared inspections and the proper use of infrared test equipment. With this Tip, we examine the importance of standards to practicing thermographers.
Anyone who has spent time in the kitchen is familiar with recipes. A typical cake recipe provides quantities of required ingredients, the order and manner in which they should be combined, and specific instructions on how to bake the batter. Following a recipe helps to ensure an acceptable range of results among those who are able to follow the subject recipe.
Both science and industry rely on standards for testing. These documents provide procedures that help to ensure that competent technologists achieve an acceptable range of results. Standards are to a thermographer what a recipe is to a baker.
Presently, several published standards are available for the science of thermography. Following standards reduces liability, increases credibility, and helps to ensure repeatability for future inspections.
Recognizing the need for standardized procedures, Infraspection Institute began publishing guidelines for thermography in 1988. Since their initial publication, Infraspection Institute guidelines have been adopted by hundreds of companies worldwide and incorporated into documents published by recognized standards organizations such as ASTM International (ASTM). Beginning in 2007, Infraspection Institute guidelines were updated and renamed as standards to reflect their industry-wide acceptance and the best practices they embody.
Each Infraspection infrared standard provides simple and straightforward procedures along with the requirements for properly documenting test results. Infraspection application standards provide a blueprint for both specifying and performing infrared inspections. These documents are a ‘must-have’ for anyone who specifies, performs, or oversees infrared inspections.
Eleven comprehensive standards covering infrared equipment operation, temperature measurement, and specific thermographic applications are available from Infraspection Institute. Copies of the latest Infraspection Institute standards are available through the Infraspection Online Store or by calling 609-239-4788.
September 21, 2020
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Making Your Own Blackbody Simulator
Tip written by: Infraspection Institute
Blackbody simulators are essential tools for checking the calibration of infrared imagers and radiometers. One alternative to purchasing a blackbody simulator is to make your own.
In order to provide accurate temperature values, infrared imagers and radiometers must be calibrated on a periodic basis. During the calibration process, blackbody simulators provide targets with a known temperature and a known emittance.
Thermographers wishing to perform a calibration check of their instruments may elect to purchase a blackbody simulator. Several models are commercially available with prices ranging up to several thousand dollars. As an alternative, thermographers may elect to make their own simulator from commonly available items. This may be accomplished as follows:
- Procure a 2 liter square metal can and a 60 Watt electric aquarium heater. Can opening must be large enough to allow heater to be inserted into can opening.
- Cover the exterior of the can with Scotch #191 PVC electrical tape.
- Fill the can with water to within 1” of the top and insert aquarium heater. Avoid causing can to overflow.
- Energize heater and set to desired temperature. Be certain to allow sufficient time for can temperature to stabilize.
When performing a calibration check of infrared equipment, set the subject radiometer’s emittance control to 0.97. Ascertain the can temperature using a thermocouple. Compare the two values and note any differences.
Lastly, be certain to work safely. In particular, avoid fully immersing any aquarium heater not designed for immersion. Be certain to disconnect the aquarium heater from its power source and allow it to cool prior to removing it from the can.
Equipment calibration is one of the many topics covered in the Level II 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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September 28, 2020
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Why Imagers & Radiometers Disagree
As the awareness of non-contact temperature measurement has increased, spot radiometers have become common tools in the workplace. Discrepancies frequently arise when temperatures taken with spot radiometers are compared to temperatures obtained with an imaging radiometer.
Advances in technology and increased sales volume have allowed several manufacturers of spot radiometers to offer a number of models priced below $100. Lower cost, combined with a greater awareness of infrared thermometry, has allowed most maintenance personnel to incorporate spot radiometers into their toolboxes.
When a thermographer reports temperatures obtained with an imaging radiometer, maintenance personnel will frequently attempt to cross-verify reported temperatures with a spot radiometer. In such situations, discrepancies are common as the spot sizes of imaging radiometers and spot radiometers often vary widely. In order to ensure measurement accuracy and avoid discrepancies, one should bear the following in mind:
- For accurate temperature measurement, radiometers must be operated correctly and in accordance with manufacturer’s instructions
- Radiometer accuracy can degrade over time or with physical stress
- Spot radiometers will generally have spot measurement sizes that are larger than imaging radiometers
- When spot measurement sizes vary between instruments, reliable cross-verification is not possible
To avoid discrepancies, personnel who utilize infrared radiometers should be trained in the proper use of their test equipment along with its limitations. Personnel must also understand how the characteristics of infrared instruments affect the accuracy of observed temperatures. Lastly, using cross-verification of temperatures should be avoided when radiometer capabilities differ from each other.
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Autumn is the Time for Steam Trap Testing
Tip written by: Infraspection Institute
With the onset of seasonably cooler weather, autumn is the time to prepare your steam system for the upcoming heating season. Testing your steam traps before the season begins can help to pinpoint costly leaks before the heating season begins.
Traditionally, two different non-destructive technologies have been employed to test steam systems – contact ultrasonics and temperature measurement. Used individually, each of these techniques has limitations that can lead to false positive and/or false negative results. Combining temperature measurement with ultrasound can result in a highly accurate test method by following a few simple steps:
- Measure trap inlet to ensure that temperature is above 212º F. If trap inlet is below 212º F, ascertain why steam is not reaching trap
- Listen to the trap outlet with contact probe of ultrasonic unit. Continuous hissing or rushing sounds usually indicate a failed trap
- Ascertain that trap is cycling periodically. Frequent cycling may be caused by an undersized or worn trap
- Tag defective traps and document in written report
- Re-test defective traps after repair to ensure effectiveness of repair
Always be sure to follow appropriate safety precautions especially when working with high pressure steam or when using ladders or lift equipment.
Infrared inspection of steam traps is one of the many topics covered in the Level I Infraspection Institute Certified Infrared Thermographer® training course. For information on thermographer training including our Distance Learning Courses, visit us online at www.infraspection.com or call us at 609-239-4788.
October 12, 2020
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IR Inspections During Motor Rebuilding
Tip written by: Infraspection Institute
Thermography can be a valuable tool for testing and monitoring in-service motors. It can also be a useful tool for detecting hidden problems within motors that are being rebuilt.
Electric motors are a vital component in most industrial facilities. In the event of catastrophic failure, facility managers often elect to rebuild large or special motors. In order to maximize the service life of a remanufactured motor, it is imperative to diagnose and correct faults during the rebuilding process since unresolved defects may shorten the life of a rebuilt motor.
For motor testing, infrared imaging may be conducted by staff thermographers employed by a motor shop or an experienced third party working at the shop. During the rebuilding process, infrared imaging may be used to diagnose problems on incoming motors and to perform quality assurance checks during the rebuilding process.
Upon arrival at the repair facility, a motor is disassembled and the rotor and stator are stripped of their coils. A high current test set is then used to excite the subject components. During excitation a thermal imager is utilized to identify thermal anomalies that are the result of short circuits and/or faulty wiring. These areas are marked so that technicians can make appropriate repairs.
Once the cause of thermal anomalies has been corrected, the rebuilding process will continue. Thermal imaging can be applied incrementally during the rebuilding process to help detect improper wiring or loose connections.
Infrared inspection of electric motors is one of the many topics covered in the Level I Infraspection Institute Certified Infrared Thermographer® training course. For more information or course locations and dates, call 609-239-4788 or visit us online at www.infraspection.com.
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October 19, 2020
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Why Building Corners Appear Cool
Tip written by: Infraspection Institute
When performing infrared inspections of framed buildings from the interior, thermographers often note that corners appear at a different temperature. With this Tip we explore the reasons for this condition and how to differentiate potential problems from normal conditions.
Corners are a common construction detail found within building walls that utilize frame construction. Corners are typically constructed with vertical framing members that both support the framed wall and provide a nailing surface for interior paneling or drywall. Although details can vary, a typical corner has three vertical studs in close proximity to each other.
More energy loss occurs at corners for two reasons: Studs are more conductive than insulation; and there is little or no space for insulation to be installed wherever corner framing studs are present. Because of this, it is normal to see greater energy loss at corners when compared to a properly insulated wall cavity.
When performing an infrared inspection of framed walls from the interior of a building with cold outdoor temperatures, corners will typically appear cooler than insulated wall cavities. Observed thermal patterns will reverse should the same inspection scenario exist with warm outdoor temperatures.
When thermographically inspecting corner details, it is normal to observe a straight vertical line from floor to ceiling. This vertical line should be confined to the corner itself and not extend onto the flat wall surfaces adjacent to the corner. Amorphous or geometric thermal patterns appearing within or adjacent to corners should be investigated for cause.
Infrared inspection of building envelopes 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 Building Envelopes, visit Infraspection Institute online at www.infraspection.com or call us at 609-239-4788.
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October 26, 2020
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Using IR Inspections to Help Prepare for Heating Season
Tip written by: Infraspection Institute
For many facilities the beginning of autumn means that heating season is just around the corner. Infrared inspections can help point out the types of energy liabilities that can account for significant waste.
With energy costs at an all time high, energy conservation is more important than ever. With companies looking for ways to contain costs, energy conservation makes sense. When properly conducted, infrared inspections can point out areas of thermal deficiencies or energy loss. When coupled with timely, effective repairs, considerable savings can be realized.
There are many areas where infrared inspections may be performed to help detect excess energy loss. Among the most common are:
- Building envelopes – for missing or damaged insulation and air leakage
- Flat roofs – to detect water damaged insulation
- Steam systems – to detect defective steam traps
- Underground piping – to detect pipe leaks
- Boilers and process equipment – to detect excess energy loss or air leaks
When it comes to the above inspections, time is of the essence in order to maximize savings. Infrared inspections should be carried out as soon as possible. Waiting until the heating season is well under way often results in documenting opportunity lost rather than savings realized.
Infrared inspection of building envelopes and thermal energy delivery systems are two of the many topics covered in the Infraspection Institute Level I Certified Infrared Thermographer® training course. This same information is also covered in our Distance Learning Level I Thermography course. For more information or to register for a course, visit Infraspection Institute or call us at 609-239-4788.
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November 2, 2020
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Determining Acceptable Load for Electrical Circuits
Tip written by: Infraspection Institute
Infrared thermography is a useful tool for detecting heat patterns caused by overloaded electrical circuits. In this Tip we discuss what constitutes an acceptable load.
Infrared imagers are capable of detecting thermal patterns associated with several electrical deficiencies including overloaded circuits. When viewed with an imager, overloaded circuits will appear warm throughout their entire length with no discrete hot spots. Since it is not possible to determine circuit load from a thermal signature, actual circuit load must be measured with an ammeter.
Once circuit load is known, a question that frequently arises is, ‘How much load is acceptable?’ The answer to this question can be found within the National Electric Code 220-10(b) which provides guidance for circuit loading.
- (b) Continuous and Noncontinuous loads. Where a feeder supplies a continuous load or any combination of continuous or noncontinuous loads, the rating of the over-current device shall not be less than the noncontinuous load plus 125 percent of the continuous load. The minimum feeder circuit conductor size, without the application of any adjustment or correction factors, shall have an allowable ampacity equal to or greater than the noncontinuous load plus 125 percent of the continuous load. NOTE: Exception: Where the assembly including the over-current devices protecting the feeder(s) are listed for operation at 100 percent of their rating, neither the ampere rating of the over-current device nor the ampacity of the feeder conductors shall be less than the sum of the continuous load plus the noncontinuous load.
In other words, for most circuits load should not exceed 80% of conductor ampacity or 80% of the overcurrent device rating. To help ensure accuracy, electric loads should be measured with a true RMS sensing ammeter.
Infrared inspection of electrical equipment is one of the many topics covered in the Infraspection Institute Level I Certified Infrared Thermographer® training course. This same subject is also the focus of our 16 hour application course, Infrared Inspection of Electrical Systems. For more information or to register for a course, visit Infraspection Institute or call us at 609-239-4788.
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November 9, 2020
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Do You Have the Correct Time?
Tip written by: Infraspection Institute
Most modern thermal imagers have the ability to record time and date along with thermal images. Taking a moment to ensure that the correct time and date are displayed on your imager before you begin your inspection can help to avoid wasted time and the collection of inaccurate data.
Having the correct time associated with your imagery is important for several reasons. With correctly dated imagery, it is possible to:
- Accurately document when the inspection was performed
- Easily store and uniquely reference image files
- Record the duration of a thermal event
It is always good practice to consciously check your imager’s clock each time you start your imager and make any necessary adjustments. Be certain to check your clock periodically during your inspection and whenever you restart your imager such as after a battery change or power interruption.
If your imager frequently displays incorrect time, it may be indicative of a defective or dead internal battery. To help avoid this problem, arrange for replacement of internal clock batteries whenever you have your imager serviced or repaired.
Infrared imager operation and use are two of the many topics covered in the Level I Infraspection Institute Certified Infrared Thermographer® training course. For information on thermographer training including our Distance Learning Courses, visit us online at www.infraspection.com or call us at 609-239-4788.
November 16, 2020
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Renting a Thermal Imager
Whether you are facing an equipment shortage or looking to evaluate the characteristics of a new imager prior to purchase, renting a thermal imager may provide a solution. As with purchasing an imager, there are several important things to consider when arranging for a rental unit.
To help ensure that you select an appropriate imager for rental, be certain to:
- Identify appropriate spectral response required for project
- Determine if temperature measurement is required
- Evaluate the system for objective specifications
- Ascertain imager compatibility with reporting software
When arranging for a rental, obtain terms and conditions from the rental agency. These should include, but not be limited to: rental period, extension of rental, shipping costs, and requirements for insurance against loss. One should also consider the rental agency’s ability to provide technical support during the rental period.
For more information on specifying an infrared imager, refer to the article, “Selecting, Specifying, and Purchasing a Thermal Imager” which may be found on this website here.
Lastly, the greatest limiting factor in any infrared inspection is the thermographer. To help ensure accurate results, infrared inspections should only be performed by properly trained and experienced thermographers. For more information on thermographer training, call 609-239-4788 or visit Infraspection Institute online.
November 23, 2020
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Training – A Wise Use of Year End Budget Money
Tip written by: Infraspection Institute
When it comes to spending year end budget monies, the phrase “Use it or Lose it” often applies. Training can be a wise choice for those looking to reduce a budget surplus.
Staying within budget is a constant challenge for maintenance managers. For many, it seems that there is never enough money in the budget. On occasion, however, it is possible to experience a surplus in one’s budget when nearing year end.
When faced with a budget surplus, it is imperative to fully utilize allocated financial resources. Failure to do so can cause a reduction in future budgeting if management perceives that your department is over funded. When searching for wise choices for year-end spending, training is always a good option.
Thermographic training is a sound investment for initiating a PdM program or expanding an existing one. Whenever considering infrared training be certain to:
- Examine course curriculum to ensure that it meets your needs
- Ensure that course will be germane to all infrared imagers
- Determine course locations or availability of Distance Learning courses
- Ascertain if certification is included with course, its expiration date, and renewal fees
- Insist that instructors be practicing thermographers with documented field experience in their area of instruction
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. Certification and applications courses are offered as open enrollment or on-site classes or through our Distance Learning program. All courses are taught by expert Level III thermographers whose field experience is unsurpassed anywhere in the world. For more information call 609-239-4788 or visit us online at www.infraspection.com.
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November 30, 2020
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Frequency of IR Roof Inspections
Tip written by: Infraspection Institute
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.
Infrared inspection of flat roofs is one of the many topics covered in all Infraspection Institute Level I training courses. For more information on thermographer training or to obtain a copy of the Standard for Infrared Inspections of Insulated Roofs, visit Infraspection Institute or call us at 609-239-4788.
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December 7, 2020
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How Delta T’s Understate Priorities
Tip written by: Infraspection Institute
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 radiometer’s 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.
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December 14, 2020
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IR Inspections of Parking Garage Ceilings
Tip Coauthored by Wayne Swirnow Infrared Imaging Services
When inspecting building envelopes for heat loss, thermographers tend to focus their imaging efforts on the sidewalls and roof. For some buildings, it is important to also thermographically inspect the underside of the building.
In many parts of the United States a common building practice for commercial structures is to elevate the building on support columns and place an unheated parking garage directly below the first story. This practice exposes the underside of the first occupied level and its associated plumbing to the outside environment.
In colder regions a common approach is to construct a suspended ceiling for the garage and to create a heated space between the underside of the first occupied floor and the garage ceiling so that water, waste, and sprinkler pipes do not freeze. To minimize heat loss, batts of glass fiber insulation are often laid directly on top of the ceiling tiles.
When performed under proper conditions, an infrared inspection of the garage ceiling can quickly reveal thermal patterns caused by missing, misapplied, or damaged insulation. Areas exhibiting excess energy loss may then be visually inspected to ascertain cause.
Infrared inspection of building envelopes is one of the many topics covered in the Infraspection Institute Level I Certified Infrared Thermographer® training course. For course information or to obtain a copy of the Standard for Infrared Inspection of Building Envelopes, visit Infraspection Institute online or call us at 609-239-4788.
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December 21, 2020
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Holiday Wishes
Tip written by: Infraspection Institute
It is hard to believe that another year has passed and the holiday season is once again upon us. With this Tip, we invite our readers to share a favorite memory as we celebrate the season.
This month marks the 50th anniversary of one of our all-time favorite programs, ‘A Charlie Brown Christmas’. As a child growing up in the 1960’s, the annual airing of this program was proof that Christmas was just around the corner.
With no reruns on broadcast television, we, like many of our childhood friends, would plan our entire week around watching this special program each year. With a cool soundtrack, the program brought our favorite Peanuts characters to life as Charlie Brown strove to discover the meaning of Christmas. To this day, Linus VanPelt’s simple monologue is one of our favorite holiday memories.
With the holidays and busy year-end schedules upon us once again, we invite you to take the time to make special memories with family and friends and to keep them in your heart where you may easily find them in the future.
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 Seffrin & the Staff of Infraspection Institute
Linus’ Monologue
Charlie Brown: Isn’t there anyone who knows what Christmas is all about?
Linus: Sure, Charlie Brown. I can tell you what Christmas is all about. Lights, please.
And there were in the same country, shepherds, abiding in the fields, keeping watch over their flock by night and lo, the angel of the Lord came upon them. And the glory of the Lord shone ‘round about them and they were so afraid. And the angel said unto them, “Fear not. For behold, I bring you tidings of great joy which shall be to all people. For unto you is born this day in the city of David, a savior, which is Christ the Lord. And this shall be a sign unto you, ye shall find the babe wrapped in swaddling clothes lying in a manger.”
And suddenly there was with the angel, a multitude of the heavenly hosts praising God and saying, “Glory to God in the highest and on Earth, Peace and Goodwill toward men.”
That’s what Christmas is all about Charlie Brown.
Excerpted from ‘A Charlie Brown Christmas’ by Charles Schulz
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December 28, 2020
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Measuring Motor Temperatures
Tip written by: Infraspection Institute
Temperature can be an indicator of the condition of installed electric motors; however, the best location for measuring temperature is often debated. In this Tip we discuss the best location for measuring motor temperatures.
Measuring motor temperature is often a challenge since electric motors differ widely in their design and construction. While many have suggested measuring the motor casing along the stator, this method does not work well for motors that are fan cooled or exposed to external air currents. For uncooled motors, this approach can produce varying temperature values depending upon the location of the subject temperature readings.
In 1997, a research project led by Infraspection Institute utilized instrumented motors in a controlled environment to determine the effect of excess force on installed motors. One of the primary goals of this research was to identify a location for collecting reliable temperature data.
From our research it was found that measuring the exterior of the motor bellhousing within 1” of the output driveshaft consistently produced temperatures that were within 1 to 2 C of the motor windings and the output side bearing assembly. Temperatures taken at the bellhousing were especially useful for fan cooled motors since this area was unaffected by convective cooling from the fan.
When measuring motor temperatures, keep the following in mind:
- Make certain that all thermometers are within calibration and used properly
- Motor temperature will vary with load and ambient temperature. Be certain to record both along with motor temperature
- Elevated temperatures can be caused by electrical or mechanical defects within the motor and/or defective installations
- Motors with elevated temperature should be further investigated for cause and repaired or replaced accordingly
Temperature limits and trending are two of the many topics covered in the Level II Infraspection Institute Certified Infrared Thermographer® training course. For more information on upcoming classes or to obtain a copy of our Cross Technologies Study, call 609-239-4788 or visit us online at www.infraspection.com.
