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Corona DetectionsCorona DetectionsCorona Detections
22.4 kV
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Ofil's new Corona camera
DayCor IIJoint development project of Ofil and EPRI
The new DayCor II bispectral Corona Camera has beendeveloped by
Ofil , in cooperation with EPRI (Electrical PowerResearch
Institute) in the US, for detection and location ofcorona on high
voltage transmission lines and substations. Theimage of corona is
unaffected by sun radiation, allowing thecamera to visualize corona
during daytime or nighttime.This capability is unique and for the
first time makes it possibleto carry out the inspection from
vehicular or airborne platformswhich can only operate in
daytime.The camera consists of two imaging channels, a UV
sensitivechannel imaging the corona and a visible channel imaging
thesurrounding scene (insulators, spacers, cables etc.). The
twoimages are overlaid to produce one video image showing thecorona
with the surrounding scene as background. The camerathus not only
detects the corona but also shows clearly thelocation of the
source.The UV channel operates in the so-called Solar Blind
range(240-280 nm) of the UV-c and is not affected by the
sunradiation. In the Solar Blind spectral range, the ozone in
theatmosphere absorbs all the sun radiation and prevents it
fromreaching the earth. Therefore, corona signals are imaged
duringdaytime with no disturbance by the sun radiation
background.The camera can also detect corona discharges on ADSS
optical cables supported by towers of high voltagetransmission
lines.The DayCor II camera is more sensitive than the DayCor I
camera. The detection distance of the DayCorII camera is about
twice the detection distance of the DayCorIThe DayCor II camera has
automatic focus for both channels (based on the visible image),
zoom capabilityin the visible channel only, and options for digital
signal processing and time integration. The UV channelhas a
catadioptric lens, specially developed by Ofil for the DayCorII,
with a large light collecting areaand 5 x 3.5 field of view.A
special counter allows semi-quantitative evaluation of the corona
strength for comparative purposes.The time integration option is
effected by reducing the number of video frames/sec. The signals
normallyappearing on several video frames are accumulated to obtain
one larger signal in one frame.The output video image is displayed
on a built-in LCD monitor. An output BNC connector allowsconnection
to an additional video monitor or to a cassette video
recorder.Compared to the DayCor I camera, the new model is improved
ergonomically. It can be operated as ahand held camera or from a
tripod.
The DayCor II Camera Operated in the Field
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Main features of the DayCor II camera:UV Optics: Catadioptric
lens.Field of view: 5 x 3.5 degrees.
Visible camera Focus: Automatic or manual UV camera Focus:
Automatic or manual,
Range: 3m to infinity.
Display Modes: Combined UV - Visibleoverlay B&W image
UV only Visible only
Integration Time: Variable up to 1.2 sec.
Sensitivity: 100 pC from 50 meter distance.
Video output: PAL or NTSC.
Controls: Auto/Manual Visible and UV focusVisible camera zoomUV
gainDisplay modes (UV/ visible/combined)Integration period (in
steps)Visible camera exposure timeStandby modeCounting mode -
Optional.
Processing: UV events counting.
Operation Voltage: 12V DC from rechargeable battery or universal
from a AC-12V DC adapter.
Power consumption: 12 Watt.
Dimensions: L x W x H = 25 cm x 17 cm x 15 cm.
Weight: 5.5 kg.
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Line: 165 kVHorizontal distance from tower ~50 m.UV Gain = 150,
RH =69%, T=24OC.
Picture captured with a Sony MAVICAP as a JPEG image
Ordering:
Camera + Backpack + 12 V battery + Charger + Case
For additional information:Visit our websites:
www.iacltda.comContact us:Tel: (571)-6232221 Fax:
(571)-2570713E-mail [email protected]
DayCor II working in the counting mode
