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The most common problems detected using infrared thermography include loose, oxidized, and high resistance connections, failing or failed components such as breakers, relays, and fuses, imbalance between phases within electrical circuits, and overloaded conditions.
A thorough infrared inspection will be both qualitative and quantitative. Qualitative because it requires a thermographer to use his training and experience to assess a particular circuit or component. Today’s infrared technology can be used to quantify the actual temperature of a given component.
Thermography measures the apparent surface temperature of an object. Infrared does not see through or into material, but the surface temperatures may allow a trained professional to interpret what is occurring below the surface.
Ideally a circuit will be fully loaded when evaluating electrical connections or components because that is the condition during which it will most likely fail. Proper evaluation takes system loading into account and must be considered when assigning a “Severity Level” to an issue. The measured temperature generally rises proportionately with the square of the current flowing through it.
Equipment should be running long enough to come up to its normal operating temperature. However, normal varies along with the environmental conditions where the equipment is located.
Not necessarily. A thermographer can make good qualitative analysis with a variety of cameras and camera capabilities. A truly professional thermographer, or thermographic inspection company should want to utilize a high resolution imager with a Noise Equivalent Temperature Difference (NETD) of 40mK or less. This will allow for the best visualization and analysis of various thermal anomalies.
Potential mistakes could include not accounting for background radiation and reflection in the analysis of an anomaly. Additionally, if providing quantitative data, not adjusting for true emissivity can drastically change the evaluation of an anomaly. Lastly, not every hot spot is an issue and cold spots should not be overlooked either.
A thorough inspection report should include the thermographer's name and training, the equipment used, and the serial number for calibration verification. Anomaly data should include: equipment identification, equipment type, amperage size, amperage measurements, location of the anomaly, related apparent temperature measurements, emissivity settings, possible cause, and a suggested remedy.
Infrared inspections should be performed at least annually. This has been a standard recommendation for decades, but as of 2023 is now a requirement pursuant to NFPA 70B. More critical components, particularly those that have been found deficient in previous inspections, may require more frequent inspections, such as bi-annual or quarterly.
arterly.
Thermography is not a substitute for, but rather a critical part of a quality electrical maintenance program.
A professional thermographer should have training under ASNT recommended guidelines SNT-TC-1ATC-101A, ideally with a Level 2 certification, or a Level 1 certification under the direction and oversight of a higher level certified thermographer.
Each company can designate its own standards or requirements for their inspection practices. The most widely accepted standard is NFPA 70B. NFPA 70B, the Standard for Electrical Equipment Maintenance, establishes mandatory requirements and guidance for developing an Electrical Maintenance Program (EMP) to ensure safety and reliability.
Others include ISO 18436-7 aimed at condition monitoring and diagnostics, including qualification and assessment of personnel performing thermographic analysis. ASTM E1934-99A (2018) defines the responsibilities of the end user and thermography and outlines the required content for documenting both qualitative and quantitative inspections.
Frequently Asked Questions
Infrared Thermography FAQs
The most common problems detected using infrared thermography include loose, oxidized, and high resistance connections, failing or failed components such as breakers, relays, and fuses, imbalance between phases within electrical circuits, and overloaded conditions.
A thorough infrared inspection will be both qualitative and quantitative. Qualitative because it requires a thermographer to use his training and experience to assess a particular circuit or component. Today’s infrared technology can be used to quantify the actual temperature of a given component.
Thermography measures the apparent surface temperature of an object. Infrared does not see through or into material, but the surface temperatures may allow a trained professional to interpret what is occurring below the surface.
Ideally a circuit will be fully loaded when evaluating electrical connections or components because that is the condition during which it will most likely fail. Proper evaluation takes system loading into account and must be considered when assigning a “Severity Level” to an issue. The measured temperature generally rises proportionately with the square of the current flowing through it.
Equipment should be running long enough to come up to its normal operating temperature. However, normal varies along with the environmental conditions where the equipment is located.
Not necessarily. A thermographer can make good qualitative analysis with a variety of cameras and camera capabilities. A truly professional thermographer, or thermographic inspection company should want to utilize a high resolution imager with a Noise Equivalent Temperature Difference (NETD) of 40mK or less. This will allow for the best visualization and analysis of various thermal anomalies.
Potential mistakes could include not accounting for background radiation and reflection in the analysis of an anomaly. Additionally, if providing quantitative data, not adjusting for true emissivity can drastically change the evaluation of an anomaly. Lastly, not every hot spot is an issue and cold spots should not be overlooked either.
A thorough inspection report should include the thermographer's name and training, the equipment used, and the serial number for calibration verification. Anomaly data should include: equipment identification, equipment type, amperage size, amperage measurements, location of the anomaly, related apparent temperature measurements, emissivity settings, possible cause, and a suggested remedy.
Infrared inspections should be performed at least annually. This has been a standard recommendation for decades, but as of 2023 is now a requirement pursuant to NFPA 70B. More critical components, particularly those that have been found deficient in previous inspections, may require more frequent inspections, such as bi-annual or quarterly.
arterly.
Thermography is not a substitute for, but rather a critical part of a quality electrical maintenance program.
A professional thermographer should have training under ASNT recommended guidelines SNT-TC-1ATC-101A, ideally with a Level 2 certification, or a Level 1 certification under the direction and oversight of a higher level certified thermographer.
Each company can designate its own standards or requirements for their inspection practices. The most widely accepted standard is NFPA 70B. NFPA 70B, the Standard for Electrical Equipment Maintenance, establishes mandatory requirements and guidance for developing an Electrical Maintenance Program (EMP) to ensure safety and reliability.
Others include ISO 18436-7 aimed at condition monitoring and diagnostics, including qualification and assessment of personnel performing thermographic analysis. ASTM E1934-99A (2018) defines the responsibilities of the end user and thermography and outlines the required content for documenting both qualitative and quantitative inspections.
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