High-voltage electrical survey advancement

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Barry Johnston
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1 High-voltage electrical survey advancement ABSTRACT Daniel A. Ninedorf Ox Creek Energy Associates, Inc. PO Box 600, Montello, WI Tel: Fax: (608) Web: Technology miniaturization has made new advancements in high voltage electrical surveying possible. A solarblind ultraviolet image overlaid onto infrared, combined with a solar -blind ultravi olet image and then overlaid onto color visible in the same camera with a weight of 6 pounds provides the comparison images and portability to allow an operator to do on-the-spot analysis and repair priority assignment. The UV-VIS image provides the quick est location and identification. The UV -IR image allows analysis to determine if there is damage and the severity. This can be accomplished in just seconds thru menu selection: before it required two separate cameras. This presentation will provide exampl es of different images and analysis, with operating time from hand -held, laboratory, vehicle and aerial camera mounts. Keywords: Corona, Infrared, High Voltage, Cameras, Substations, Transmission Line, Inspection INTRODUCTION In 1997 Mr. Roel Stolper 1. a research engineer at the CSIR in M&M Tek division began looking for a daylight 2. corona camera to make the inspection of electric utility transmission lines from a helicopter possible and safer. Up to this time corona inspection were accomplished in l ow-light environments using cameras developed by Roel. In 2000 the daylight corona camera began field testing and operation evolving with additional capabilities to colorize the corona to contrast with the background, to filter the corona to remove noise ultraviolet light, and to integrate the corona image to be able to distinguish smaller quantities. Concurrent with the development of corona cameras, but in more widespread use were infrared cameras, these cameras were also evolving and becoming smaller, the technology of measurement was also advancing, taking into account background temperatures, distance to item being observed, and the emissivity of highly conductive metals such as aluminum and the effect of temperature on emissivity. High voltage electrical equipment is typically made of highly conductive aluminum alloys which are the most difficult to accurately measure temperature using infrared. In research facilities and in manufacturing facilities where it is desirable to measure the temperature of aluminum reliably or on predictive maintenance routes the infrared technicians apply a short piece of black electrical tape to keep the emissivity constant at 0.95 which may also be accomplished with some powders and paints having specific emissivity s. The energized state of the items observed make the emissivity correction steps impossible except in the lab, thus comparison between phases is a good means and the fact that if the device is extremely hot it doesn t matter what the emissivity is, imminent re pairs are required. When the corona cameras were developed it was expected by infrared camera users that the evolution would have infrared and corona cameras be in the same camera case. Some infrared techs have resisted incorporating the two technologies, other manufacturers misleading marketing may lead this resistance. The understanding of what is seen with an infrared camera under these conditions is still evolving and the corona technology is gaining understanding also. The combination of these technolo gies, concurrent images with infrared and corona create a new level of understanding and an opportunity to reduce inspection costs by reducing survey time and potentially the equipment costs and increase the information by looking concurrently at the objec ts. The evolution includes accessories such as low power, light -weight, daylight viewable, high -resolution LCD displays that enlarge the image showing as much detail as possible and the zoom capability of the display and camera. In addition the ergonomic s of portable cameras require light -weight high power capacity batteries, image and video recording with audio clips or detailed audio descriptions, Global Position Sensing (GPS) built -in to record the camera location at the time the image was taken, and c ontinual review of the technologies available to increase the operators knowledge of the weather and other contributing factors to when corona will occur.

The following pictures show a distribution voltage electrical inspection: Fig. 1 Corona on infrared Fig. 2 Corona on visible Fig.

the solar heating on the many items on the pole. Figure 2 is a visible image wit h corona overlaid, which shows the corona activity (red color) more distinctly.

The concurrent zoom is in the visible and UV and infrared images.

2 The following pictures show a distribution voltage electrical inspection: Fig. 1 Corona on infrared Fig. 2 Corona on visible Fig. 3 Zoom to find more damage Figures 1 is an infrared image with corona overlaid, which does show added heat where the corona is, but not enough to attract the attention of most camera operators due to the solar heating on the many items on the pole. Figure 2 is a visible image wit h corona overlaid, which shows the corona activity (red color) more distinctly. Figure 3 as you can see, bigger is better to show the damaged lightening arrestor, thus the cameras are equipped with concurrent zoom and start with a default 110mm lens resolution. The concurrent zoom is in the visible and UV and infrared images. Thus a quality high voltage inspection requires a thorough visible inspection for structural, electrical defects, and discoloring indications of corona activity or heating from arcing; a corona inspection is looking for active corona which an experienced operator understands has most likely times to occur and the indications that are meaningless such as when a rain creates droplets or under freezing condition icicles with corona on the end. Infrared inspection requires a comparison of electrical component temperatures that should be carrying the same current flow while observing for solar -heating (as shown on the distribution voltage pole above) and understanding that the best infrared inspection is done on cloudy days or at night and with low winds and approximately equal phase current loads.

The following images are from a non-ceramic insulator: Fig. 4 Fig.

insulator needs a corona ring to control the electrical field intensity. Without a corona ring the NCI will self -destruct within 10 years versus the design life of 60 to 80 years.

present. The spider webs are also visible on the energized ceramic post Insulators in nearly all applications are routinely cleaned to remove contaminants that may lead to flash - over.

3 The following images are from a non-ceramic insulator: Fig. 4 Fig. 5 These images (inf rared on left, visible on right both images have look-thru corona color displayed) indicate where a non -ceramic insulator has severe (audible) corona activity present, the insulator needs a corona ring to control the electrical field intensity. Without a corona ring the NCI will self -destruct within 10 years versus the design life of 60 to 80 years. Using the look thru display mode the operator is saved many words describing that the corona is at t he junction of the metal connector on the insulator and the jacketed fiberglass rod of the insulator. The corona by -products will rapidly deteriorate the insulator cover and deposit acid upon the (typically) hollow fiberglass strength rod which results in conductive spots that can have arcing plasma present. The spider webs are also visible on the energized ceramic post insulator. Insulators in nearly all applications are routinely cleaned to remove contaminants that may lead to flash - over. The next example is in an electrical substation with corona on energized hardware and insulators: Fig. 6 Fig. 7 Same as 6 with decreased UV gain. These visible images are to show how using the UV gain on the corona camera, menu selected and adjustable electronic filters enable the camera operator along with the angle or line -of-sight to accurately describe where the corona activity is occurring and describe which is detrimental. Corona is line -of-sight and may not be visible from all angles, daylight corona is the nitrogen in the air changing state due to the electrical field intensity. This intensity may be due to a distortion of the elec trical field due to a sharp point (bolts or wire) or a void in an insulator causing internal partial discharge and corona above the defect.

4 This is an example of applying the same technology for border security: Fig. 8 Fig. 9 Fig. 10 These images show the versatility of this type of camera configuration and potential addi tional applications beyond electrical inspection including border security.

Another application where the Multi camera configuration

interstate, which started and burned out probably without

The infrared images indicate where the hot flames are,

5 Another application where the Multi camera configuration is highly desirable is new fire detection: Fig. 11 Fig. 12 Fig. 13 Fig. 14 This set of images shows a grass fire alongside an interstate, which started and burned out probably without suppression. The infrared images indicate where the hot flames are, the ultraviolet indicates where new flames are. The visible image also shows a vehicle moving at 70mph thru the line -of-sight, not thru the flames.

6 In Conclusion: A need for highly portable, menu selectable adjustment, daylight corona cameras has evolved by end-user demand to incorporate infrared cameras in a Multi spectral camera housing which allows the camera operator to locate a problem, adjust the camera to best display the problem in each optical mode, quickly create multiple detailed images by zooming as required, and provide a detailed audio description of the problem, the problem location is documented by GPS readings on the image, the date and time are also on the image along with labels of the facility as desired. Future evolution will include the full radiometric infrared camera and sensors (atmospheric pressure, ambient temperature, etc.) to document the corona and infrared contributing factors. The preceding images and text describe a highly versatile camera configuration which with the push of a single button changes the background image from infrared to color visible, the solarblind ultraviolet can image the nitrogen activity in electrical corona or some flames. The ultraviolet light emitted by corona is a very weak signal requiring high sensitivity photo detectors and the solar-blind filters enable high voltage electrical applications to be performed safely whether in a substation, from a helo flying a transmission line or the testing of a motor or generator winding. The combination with visible or infrared enable the ultraviolet light detected to be overlaid onto that image to provide precise placement of the UV light source, the relative magnitude by its intensity which can also indicate the potential for flash-over or power arcing or electrical plasma. The infrared light can be calibrated to indicate the relative temperature of objects, this reading is then corrected with an emissivity factor, distance and reflected energy to arrive at a precise temperature. The evolution of the Multi spectral camera is rapidly proceeding and full radiometric infrared cameras will be incorporated soon. The camera also stores the images on a memory card or by video output along with audio description to enable the operator to instantly make notes including valuable descriptive information which would otherwise be lost. References: 1. The design and evaluation of a Multi-Spectral Imaging Camera for the inspection of transmission lines and substation equipment by Roel Stolper and Jaco Hart, CSIR and N Mahatho, Eskom, South Africa 2. MultiSpectral Camera Development 2001 by Dr. Dzevad Muftic, Manager, Line Engineering Services, ESKOM; Mace Technology; Gustavo Alonso, Hangar Servicios, Argentina

Introduction. Corona. Corona Cameras. Origo Proposed Corona Camera. Origo Corporation Corona Camera Product Inquiry 1

Introduction. Corona. Corona Cameras. Origo Proposed Corona Camera. Origo Corporation Corona Camera Product Inquiry 1 Origo Corporation Corona Camera Product Inquiry 1 Introduction This Whitepaper describes Origo s patented corona camera R&D project. Currently, lab and daylight proof-of-concept tests have been conducted