Understanding Infrared Thermography Reading 7 Part 2 of 2.pdf

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The processing electronics unit amplifies and conditions the signal from the infrared detector and introduces corrections for such factors as (1) detector ambient temperature drift and (2) target surface emissivity. Generally, a meter indicates the target temperature and an analog output is provided. The analog signal is used to record, display, alarm, control, correct, or any combination of these. Figure A-14 illustrates the configuration of a typical instrument employing all of the elements outlined. The germanium lens collects the energy from a spot on the target surface and focuses it on the surface of the radiation thermopile detector. The 8.14 µm filter limits the spectral band of the energy reaching the detector so that it falls within the atmospheric window. The detector generates a dc emf proportional to the energy emitted by the target surface. The autozero amplifier senses ambient temperature changes and prevents ambient drift errors. The output electronics unit conditions the signal and computes the target surface temperature based on a manual emissivity setting. The analog output terminals accept a 15 - 30 VDC loop supply and generate a 4 - 20 milliampere signal, proportional to target surface temperature. Charlie Chong/ Fion Zhang
All infrared detector-transducers exhibit some electrical change in response to the radiant energy impinging on their sensitive surfaces. Depending on the type of detector this can be (1) an impedance change, (2) a capacitance change, (3) the generation of an emf (voltage), or (4) the release of photons. Detectors are available with response times as fast as nanoseconds or as slow as fractions of seconds. Depending on the requirement, either a broadband detector or a spectrally limited detector can be selected. Keywords: Depending on the type of detector this can be (1) an impedance change, (Z) (thermal detector?) (2) a capacitance change, (C) (thermal detector?) (3) the generation of an emf (voltage), (Emf) (thermal detector?) (4) the release of photons. (E=hѵ) (photon detector?) Charlie Chong/ Fion Zhang
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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
Page 71 and 72: Reflections off Specular and Diffus
Page 73 and 74: The thermogram of the outside surfa
Page 75 and 76: Steady-state conduction Steady stat
Page 77 and 78: A.3 The Basic Physics of Infrared R
Page 79 and 80: A.3.1 Some Historical Background Th
Page 81 and 82: A.3.3 The Target Surface The chart
Page 83 and 84: Figure A-6 shows the distribution o
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Page 87 and 88: Two physical laws define the radian
Page 89 and 90: According to (2), the wavelength at
Page 91 and 92: Figure A-7 Spectral Distribution of
Page 93 and 94: Figure A-8 shows that the instrumen
Page 95 and 96: If the emissivity of a gray body is
Page 97 and 98: Under certain conditions, an error
Page 99 and 100: EXAM score! Non-graybody (colored b
Page 101 and 102: Figure A-10 illustrates the spectra
Page 103 and 104: Figure A-10 Infrared Transmission o
Page 105 and 106: Figure A-11 Infrared Spectral Trans
Page 107 and 108: Figure A-11 shows transmission curv
Page 109 and 110: EXAM score! Glass is opaque λ > 5
Page 111 and 112: Figure A-12 Characteristics of IR T
Page 113 and 114: The characteristics of the window m
Page 115 and 116: IR Lenses - LWIR Len Charlie Chong/
Page 117 and 118: IR Lenses - Fresnel Len Charlie Cho
Page 119 and 120: Figure A-13 Components of an Infrar
Page 121: Infrared optics are available in tw
Page 125 and 126: Figure A-14 Typical Infrared Radiat
Page 127 and 128: Germanium Len Charlie Chong/ Fion Z
Page 129 and 130: Thermopile Detector Charlie Chong/
Page 139 and 140: The IR Detectors Infrared detectors
Page 141 and 142: Figure A-15 Spectral Sensitivity of
Page 143 and 144: The Mercury- Cadmium-telluride (Hgc
Page 145 and 146: The Mercury- Cadmium-Telluride (HgC
Page 151 and 152: Point-sensing instruments for measu
Page 153 and 154: A.3.6.1 Line Scanning The purpose o
Page 155 and 156: A.3.6.2 Two-Dimensional Scanning Th
Page 157 and 158: Opto-mechanical Scanner A typical c
Page 159 and 160: Electronic scanning Electronic scan
Page 161 and 162: Figure A-18 Schematic of a Typical
Page 163 and 164: Applications for infrared FPAs incl
Page 165 and 166: Staring Charlie Chong/ Fion Zhang
Page 167 and 168: A.4.1 Point-Sensing Instruments For
Page 169 and 170: Temperature sensitivity is also cal
Page 171 and 172: 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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Figure B-4 Using the Transmittance
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Appendix C Quick Reference Charts A
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MTF Determination Using An Ir Image
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Measuring And Setting Effective Emi
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Classification Of Faults (Guideline
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Reading: Four Emissivity: Understan
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Figure 1 shows a typical three-phas
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Figure IR1: Corresponding infrared
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Thermal radiation and properties of
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The thermal nature of materials. Ma
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So in plain English, when the therm
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Figure 2: Stainless steel block. (a
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Observed with our thermal imager (w
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Can you see my eye glasses in the i
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How can the thermal imager’s read
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When we remove the block from the o
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In this experiment we see that the
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Charlie Chong/ Fion Zhang http://ww
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Using a narrow band filter to measu
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Emissivity, the variable’s variab
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Emissivity and electrical equipment
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In manufacturing processes, steel o
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In this case, we have another power
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Figure IR1: Corresponding infrared
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Figure 7: Measuring the loads on a
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Summary Predictive maintenance PDM
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It is much like most endeavors in l
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Good Luck Charlie Chong/ Fion Zhang
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Charlie https://www.yumpu.com/en/br
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