Infrared Thermography: Power Quality Among Other Things

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  • Case for Infrared is broader than only Power Quality.Poor electrical connections includes loose neutrals.
  • Improper torque of componentsMust have current.
  • Clips can anneal over time increasing the contact resistance, thereby causing hot spotsConnections within molded-case breaker
  • The chart indicates both the frequency and wavelength. As the frequency increases the wavelength decreases, vice versa.The higher the frequency the greater the energy. For example, the highest frequency energy depicted is gamma rays, which are so energetic there known as ionizing radiation. It is worth noting that the visible spectrum is sandwiched between the UV & IR. On the right we see radio waves. At around 10 to the twelfth hertz or 1 terahertz the characteristics of the energy is finding a number of new uses.
  • Sir William Herschel
  • Germanium is an element that is opaque to visible light. However it is transparent to IR.Obviously, glass is transparent to visible light.Another example, clothing is opaque to visible light. However, clothing is transparent to electromagnetic wave called the terahertz waves or T-waves. In the future, terahertz waves will be used in security in place of backscatter x-rays.
  • A space blanket (also known as a Mylar blanket, first aid blanket, emergency blanket, thermal blanket or weather blanket) is a blanket used in emergencies to reduce heat loss in a person's body caused by thermal radiation, water evaporation and convection.
  • The above triangle is not an exact mathematical representation. The triangle is only used as an analogy to the power triangle to help viewers having an electrical background generally understand the physics of the IR camera.
  • The lens is made of germanium, which filters visible light frequencies.
  • Can be like looking at the world through a pin-hole.Can be expensive and should prioritize use to vital few and trivial many.
  • Assume balanced loadDiagrams above assume third harmonic is a third the magnitude of the fundamentalCurrents above viewed from line and neutral, respectivelyThe third harmonic line currents are superimposed on top of each other appearing as one current. For this reason, the third harmonics add algebraically having a substantial magnitude.
  • Infrared Thermography: Power Quality Among Other Things

    1. 1. May 30 , 2013Presenter: Gary Malhoit, P.E.1
    2. 2. Agenda Why Infrared? Infrared Basics Power Quality, Heat & Reliability Questions & Comments: All2
    3. 3. Heraclitus (535-475 BC)3“No man ever steps in the same river twice."
    4. 4. National Fire ProtectionAssociation The National Fire Protection Association (NFPA) wasestablished in 1896 by concerned losses due to fires. A primary cause of industrial fires and losses, as wellpersonal injury accidents, over the last five decades isrelated to electricity. NFPA recommends that “routine infrared inspectionsof energized electrical systems should be performedannually.4
    5. 5. Case for Using Infrared Generally Non-Invasive Process (Safety) Improve Power Quality by Identifying Poor ElectricalConnections (Voltage Drop Issues) Improve Power Quality by Identifying High NeutralCurrents Reduced Risk of Unplanned Outages (Reliability) Reduced Risk of Fire (Insurance Discounts)5
    6. 6. Prioritize Infrared Work6
    7. 7. Inductive Logic and Risks7
    8. 8. Poor Connections & Heat8Non-ConductingHot Conducting Cross-Section (A)Conductor Cross-SectionsHotterHot Conducting Cross-Section (A)Non-Conducting
    9. 9. Heat & Diminishing Reliability9FailureRateTimeInfantMortalityNormal Life Wear OutHeatBathtub curve derived from threeWeibull Distributions
    10. 10. Some Types of Connections10Bolted ConnectionsClip ConnectionsCrimp & Bolted Connections
    11. 11. Fuse Clamps11
    12. 12. Heat Transfer Conduction ConvectionRadiation12Source: Earthforce.com
    13. 13. Electromagnetic Spectrum Light comprises only a small portion of the entireelectromagnetic spectrum. Most of the electromagnetic spectrum is invisible tothe human eye.13
    14. 14. Above Absolute Zero All objects emit infrared above absolute zero The warmer the object, the greater the intensity ofemitted infrared radiation.14Source: FLIR Course Manual
    15. 15. Hot Steel Glowing IncludesEmitted Energy Hot steel emitting light or energy in at least the visibleportion of the electromagnetic spectrum. Not all hotmetals glow visually like steel, for example aluminum.Emitted Energy= K T415
    16. 16. Herschel’s Experiment (1800)16Blue: 80 degreesYellow: 83 degreesInfrared: 86 degreesSource: FLIR Course Manual
    17. 17. Opaque and Transparent Transmitted light is limited to transparent objects. The frequency of the electromagnetic energy sourcecan determine if an object is opaque or transparent.Opaque TransparentAbsorbedAbsorbedReflected ReflectedTransmitted=0Transmitted=017Germanium GlassVisible Light Visible Light
    18. 18. 18Opaque TransparentOpaque and Transparent(cont.)Source: FLIR Course Manual
    19. 19. Commonly Used InfraredWavelength (Microns)19Near IRLong IRMid IR NotUsedNotUsed(Used for Thermography)Source: FLIR Course Manual
    20. 20. What is a Blackbody? A blackbody is a perfect or ideal absorber or emitterof radiation at a temperature above absolute zero. In reality, a black body does not exist.20If λ<dλCavity with opaque wallsIf λ>dBlackbody RadiationReflection & DiffractionOpening (diameter=d)
    21. 21. Emissivity (ε) Emissivity is the ability of an object to emit radiationand is the ratio of emission from an object ascompared to a black body. Emissivity of a Blackbody is 1.Emissivity = ε =Actual Emission from Object at temperature TEmission from Blackbody at temperature T21
    22. 22. Emissivity of CommonMaterials at 300°Kelvin Aluminum Foil .04 Masonry Plastered 0.93 Nickel 0.03 Paint 0.96 Glass 0.93 Tile 0.97 Copper 0.03 Granite 0.45Note: Metals have a low emissivity!!22
    23. 23. Emitted, Apparent & ReflectedApparent Temperatures23Emitted TemperatureApparent TemperatureReflected ApparentTemperature (RAT)(1-ε)εTargetCameraAttempt to match the emissivity setting of the camera to theemissivity of target.Reflectivity
    24. 24. Planck’s Law (1900) Classical theory called for infinite energy at the higherfrequencies and is referred to as the Ultravioletcatastrophe Max Planck determined electromagnetic energy isemitted in discrete packets of energy proportional tofrequency24Source: WikipediaDepicted curvespresume blackbodies
    25. 25. Camera Schematic25ProcessorTarget Filter SensorInfraredVisibleε, RATTApparentTe
    26. 26. IR Detector DevicesIR detectors consists of generally two types of devices: Un-cooled – Most common and functions at roomtemperature and is generally made using compoundsemiconductors (e.g., Lead Selenide & IndiumAntimonide). Cryogenically cooled - More expensive and moreaccurate though more susceptible to damage andrequires cryogenically cooling.26
    27. 27. Grayscale PaletteWatertown, MAApril 19, 201327
    28. 28. Ironbow Palette28
    29. 29. Rainbow Palette29
    30. 30. Transparent Windows30
    31. 31. Electrical Tape on Three MetalCans Electrical Tape (.95) has much higher emissivity thanmetal (.2) of can.Visual InfraredHotCanCan atRoomTemp.ColdCanHotCanCan atRoomTemp.ColdCan31
    32. 32. Priority Rating Table32Δ= 96 F°
    33. 33. Loaded Circuit33
    34. 34. 34
    35. 35. Poor Fuse Connection35
    36. 36. Third Harmonics36
    37. 37. Harmonics & Heat(Skin Effect)37DC: No Skin Effect 60 Hz: Skin Effect 1 KHz: Substantial Skin EffectRegion of most current flow=δSkin Depthδ
    38. 38. Third Harmonics (cont.)38Could be unbalanced Situation?
    39. 39. Loose Neutral39
    40. 40. Heat Pattern Dissipates fromLose Connection40
    41. 41. Inductive Heating: Iso-PhaseBus41
    42. 42. 42Strap Between Section of ISOPhase Bus
    43. 43. Infrared Applications43Source: Wall Street Journal
    44. 44. Future of Infrared44
    45. 45. Comments & Questions?45

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