Understanding Infrared Thermography Reading 7 Part 2 of 2.pdf

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So, just observing that there is a hot spot does not indicate a problem. Electrical components can be appropriately hot for the electrical load and conditions. If you measure the loads, you can determine if the presence of a thermal anomaly indicates a problem. Thermal imagers do not identify thermal problems – trained, knowledgeable, qualified people make educated assessments of equipment. This leads to real value in preventive maintenance and reduced frequency of equipment breakdowns. Charlie Chong/ Fion Zhang http://reliableplant.com/Read/14134/emissivity-underst-difference-between-apparent,-actual-ir-temps
Summary Predictive maintenance PDM with a thermal imager can be effectively performed by utilizing qualitative analysis of equipment. Qualitative techniques allow the emissivity setting on the thermal imager to be kept at 1.0 and apparent temperatures used for comparisons between similar equipment under similar load. With basic training, most technicians can reliably perform qualitative analysis. Quantitative infrared analysis requires a deeper understanding of thermal theory and application to be truly effective. It refers to the attempt to measure actual temperatures of materials using infrared thermography. Actual temperature measurement involves more than simply adjusting for emissivity. Total incident radiance requires dealing with the effect of reflection and transmission in addition to emissivity. Today’s thermal imagers are becoming increasingly affordable and easy to use. But, what does easy mean? The practice of infrared thermography looks straight forward and simple; but it has its tricks. It is much like most endeavors in life: the more you learn, the more you discover that there is more to learn. Charlie Chong/ Fion Zhang http://reliableplant.com/Read/14134/emissivity-underst-difference-between-apparent,-actual-ir-temps
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Infrared Thermal Testing Reading VI
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6.1 Basic Elements An in-house prog
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6.1.4 Responsibilities This section
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IR Viewing Window - Opaque Polymer
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6.1.8 Acceptance Criteria All surve
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6.1.9 Reporting Criteria A rigid pr
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6.1.10 Qualification of Personnel P
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EPRI Licensed Material Basic Elemen
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7. TRAINING AND CERTIFICATION This
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Recommended training and certificat
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■ Level II A Level II infrared th
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The experience and education recomm
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B. Spatial Resolution • the conce
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D. Equipment Operation • Be able
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The PdM basic examination is more s
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Appendix-A The Science Of Thermogra
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Erroneous conclusions can have an e
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A.2.1 Heat and Temperature What is
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To convert changes in temperature o
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A.2.3 The Three Modes of Heat Trans
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The Fourier Conduction Law: Q/A Q =
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A.2.5 Convection Convective heat tr
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Figure A-2 Convective Heat Flow Cha
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A.2.6 Radiation Radiative heat tran
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A.2.7 Radiation Exchange at the Tar
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Charlie Chong/ Fion Zhang
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Figure A-4 Radiative Heat Flow W ε
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A.2.8 Specular and Diffuse Surfaces
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Specular or Diffuse Surfaces Diffus
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Specular and Diffuse Surfaces Confu
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Specular reflection is the mirror-l
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Reflections off Specular and Diffus
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The thermogram of the outside surfa
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Steady-state conduction Steady stat
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A.3 The Basic Physics of Infrared R
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A.3.1 Some Historical Background Th
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A.3.3 The Target Surface The chart
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Figure A-6 shows the distribution o
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Two physical laws define the radian
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According to (2), the wavelength at
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Figure A-7 Spectral Distribution of
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Figure A-8 shows that the instrumen
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If the emissivity of a gray body is
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Under certain conditions, an error
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EXAM score! Non-graybody (colored b
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Figure A-10 illustrates the spectra
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Figure A-10 Infrared Transmission o
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Figure A-11 Infrared Spectral Trans
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Figure A-11 shows transmission curv
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EXAM score! Glass is opaque λ > 5
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Figure A-12 Characteristics of IR T
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The characteristics of the window m
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IR Lenses - LWIR Len Charlie Chong/
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IR Lenses - Fresnel Len Charlie Cho
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Figure A-13 Components of an Infrar
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Infrared optics are available in tw
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All infrared detector-transducers e
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Figure A-14 Typical Infrared Radiat
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Germanium Len Charlie Chong/ Fion Z
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Thermopile Detector Charlie Chong/
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The IR Detectors Infrared detectors
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Figure A-15 Spectral Sensitivity of
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The Mercury- Cadmium-telluride (Hgc
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The Mercury- Cadmium-Telluride (HgC
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Point-sensing instruments for measu
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A.3.6.1 Line Scanning The purpose o
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A.3.6.2 Two-Dimensional Scanning Th
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Opto-mechanical Scanner A typical c
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Electronic scanning Electronic scan
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Figure A-18 Schematic of a Typical
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Applications for infrared FPAs incl
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Staring Charlie Chong/ Fion Zhang
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A.4.1 Point-Sensing Instruments For
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Temperature sensitivity is also cal
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EXAM score! thermal resolution (≠
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NETD - Noise Equivalent Temperature
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Figure A-19 Instrument Speed of Res
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Figure A-20 Fields of View of Infra
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Figure A-20 Fields of View of Infra
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The output requirements are totally
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Spectrally selective instruments em
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Figure A-21 Spectral Filtering for
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Figure A-22 shows a similar solutio
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A.4.2 Scanners and Imagers.Qualitat
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• Total field of view (TFOV): the
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Despite some manufacturers’ claim
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A.4.3.1 Temperature Sensitivity, Mi
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Figure A-23 Test Setup for MRTD Mea
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A.4.3.2 Spot Size (FOV) , Instantan
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■ A standard 4 bar (slit) resolut
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Both MRTD and MTF are functions of
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IFOVmeas: The slit width at which t
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FPA Charlie Chong/ Fion Zhang http:
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FPA Charlie Chong/ Fion Zhang
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A.4.3.3 Speed of Response and Frame
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A.4.4 Thermal Imaging Software In o
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The newest field-portable instrumen
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Appendix B Measuring Emissivity, Re
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Figure B-1 Target Radiosity Charlie
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The reference emitter technique wor
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1. Apply the reference emitter (E)
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B.2.2 Reflective Emissivity Techniq
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Figure B-3 Using the Reflective Emi
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Page 235 and 236: Appendix C Quick Reference Charts A
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Page 239 and 240: Measuring And Setting Effective Emi
Page 241 and 242: Classification Of Faults (Guideline
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Page 247 and 248: Figure 1 shows a typical three-phas
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Page 251 and 252: Thermal radiation and properties of
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Page 255 and 256: So in plain English, when the therm
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Page 263 and 264: How can the thermal imager’s read
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Page 271 and 272: Using a narrow band filter to measu
Page 273 and 274: Emissivity, the variable’s variab
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Page 281 and 282: Figure IR1: Corresponding infrared
Page 283: Figure 7: Measuring the loads on a
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Page 289 and 290: Good Luck Charlie Chong/ Fion Zhang
Page 291: Charlie https://www.yumpu.com/en/br
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