Ox Creek Energy Associates Inc Ox Creek Energy Associates Inc SDVeteranOB Dan Ninedorf Corona Technology Course Instructor & Co- Developer Level II Infrared Technician Electrical Power Engineering Tech over 45 years of high voltage experience over 20 years of IR-UV-Visible camera experience - answers your question's series - The first question typically is - What Will Corona See That Infrared Will Not ? --- Arrow keys to advance slide. -- Copyright 2013 Ox Creek Energy Associates Inc
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Ox Creek Energy Associates IncOx Creek Energy Associates IncSDVeteranOB
Dan NinedorfCorona Technology Course Instructor & Co-Developer
Level II Infrared TechnicianElectrical Power Engineering Tech
over 45 years of high voltage experienceover 20 years of IR-UV-Visible camera experience
- answers your question's series -
The first question typically is -What Will Corona See That Infrared Will Not ?
--- Arrow keys to advance slide. --
Copyright 2013 Ox Creek Energy Associates Inc
Corona Camera vs Infrared Camera Under Construction -Under Construction - The following slides will show The following slides will show
where this is going as fast as where this is going as fast as possible.possible.
Your questions are welcome, Your questions are welcome, email:email: [email protected]@maqs.net
Corona Camera vs Infrared Camera Daylight corona camera Senses light photons in the
range 260-300nm, subject to reflections on water droplets in the air.
Corona (ultraviolet photon detector image) overlaid onto color visible image, in “real time”.
The corona detector is slaved to the Visible camera typically thru at least part of the visible cameras “zoom” range.
Corona cameras ”default field of view” is typically at 100mm, and “zoom” from there.
Infrared Camera Electrical - Typically long-wave 8-12
micron (8,000-12,000nm) Senses heat radiated from objects,
subject to reflections from sun, shiny surfaces or holes.
Infrared image & may have visible image camera.
Infrared cameras do not “zoom”, they focus at a “field of view (FOV)”, then can be adjusted to focus at a different “distance” with same FOV.
Infrared cameras “default field of view” is typically 35 to 50 mm lens, change lens to “focus at a smaller or larger “field of view”. Lens can cost thousands of dollars..
Corona Camera vs Infrared Camera Lets consider these statements. A graph can show the light emission spectrum. No single sensor can see all of the spectrum. The Corona Camera sensor is much more sensitive then current
Infrared Camera sensors. With a daylight corona camera I have seen the indication of corona across a mountain valley one mile away.
Everything has a temperature and for our purposes can be seen with an infrared camera.
Long-wave infrared is the choice for outdoor, low-emissivity hardware that electrical inspectors look at, due to less solar reflection which causes erroneous temperature readings.
Companies may select an emissivity standard to use for all infrared scans, typically between 0.85 and 0.95 depending upon the materials they look at and personal choice.
Corona Camera vs Infrared Camera Lets consider these statements. Some light sources emit across many wavelengths at different intensities at
different times (the sun). Chemical sources block light in only discrete wavelengths, that are called
absorption bands, this can be used to locate gas leaks and identify specific chemicals, such as SF6 gas leaks. A normal infrared camera is not filtered and cannot isolate wavelengths to see these gases because other wavelengths “over-power” the missing signal in the absorption band.
Day-light corona cameras development was enabled because the ozone layer surrounding the earth absorbs the sun light in the 260-300nm wavelengths making these wavelengths on earth pitch black around the clock, except for mostly man-made light sources, such as fire, florescent lights, corona, arcing, arc welding, which all change the state of the nitrogen in the air or emit photons visible in the 260-300 nm band.
Daylight corona cameras were developed to enable scanning of remote electric transmission lines from helicopters, and because a helicopter can scan power lines over crop fields or urban areas without disruption, getting stuck in mud, and much quicker, a rough number can be 90 towers a day on flat land by helicopter versus maybe10 from a vehicle. Scanning from a helo does not replace the need to follow-up from the ground, to do in-plant surveys, R&D, distribution voltage, and more.
Corona Camera vs Infrared Camera Seeing corona is the first step, which requires a quality low-light
or day-light corona camera dependent upon application. Understanding the probable causes of corona in that situation
(materials, shape, voltage, …) is the next step. The answer to the question OK You found corona, what does it mean.
From experience deciding if that corona is detrimental and what repair priority or monitoring is needed.
Corona can produce excessive noise resulting in complaints. Arcing can produce radio/tv interference (RFI) for a mile around
that neither infrared or ultrasound can locate. But a daylight corona camera can see from nearly a mile away.
Micro-Arcing (inside connectors) can occur that causes RFI and corona that infrared cannot image.
Corona Camera vs Infrared CameraSo a corona camera images the ultraviolet light
emitted during the change in state of nitrogen in the air due to electrical field intensity or during the initial burning of vegetation.
The electric field intensity around energized equipment can exceed the breakdown strength of air, when this happens corona starts.
The exact voltage to cause corona is dependent upon the shape of the object, the object's proximity to other secondary objects, there shape, applied voltage and polarity, the altitude, wind speed, ambient temperature, humidity -primarily when condensing, when it can act like stepping stones in creating a flash-over path, the same occurs when a contaminated object is drying unevenly.
So it can be said that a corona camera displays when the relative voltage (electric field intensity) on an object exceeds the relative breakdown strength of air.
So an infrared camera images the temperature of objects.
Electric current flow changes the temperature of electrical equipment and electronic devices.
When the temperature of electric equipment exceeds 20 to 50F above ambient temperature (based upon standards) or when compared to the temperature of other phases in the circuit, preferred load is 40% conductor capacity or higher at less then 10mph wind.
So it can be said that an infrared camera displays the temperature of object(s) due to current flow in those object(s.)
Corona Camera vs Infrared Camera The MultiCAM developed by CSIR (now built
by UViRCO Technologies (Pty) Ltd) is the first -and only- camera to combine the ability to simultaneously image corona and infrared and visible.
This is done by precisely overlaying two images -one corona image overlaid onto one infrared image -of the exact same Field of View (FOV)- or with the push of one button corona onto a visible image. This is done in real time with a NTSC video output for recording and image storage.
Corona Camera vs Infrared Camera So at any time the MultiCAM has 3 image's
or 3 video streams available for viewing.
Using one push button the operator selects corona overlaid onto infrared or by pushing the button corona overlaid onto visible.
Corona overlaid onto visible is common to all daylight corona cameras.
Scanning with corona overlaid onto infrared should find all problems.
Corona color, selecting a color not in the infrared palette or not blending into the clouds is better for contrast, easier to spot problems.
Scan with corona gain at maximum until an object of interest is located. Then adjust the gain for the best image to tell the story.
Corona Camera vs Infrared Camera
Corona (red blob's) overlaid onto infrared image
Corona overlaid onto visible image
Corona Camera vs Infrared Camera
Corona at maximum gain on infrared
Corona at maximum gain on visible
Corona Camera vs Infrared CameraIn 2000, The CoroCAM IV+
introduced daylight corona cameras.
In late 1985, The CoroCAM 504 became the world's most