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UV-IR complimentary technologies TOC Can the corona camera replace the IR technology? What is the difference between IR and corona inspections ? How can I use the UV & IR technologies to have complete overview? “A picture is worth thousand words” Live End Corona Dead End Corona No corona on IR picture Corona spots using UV technology “A picture is worth thousand words” No corona on IR picture Corona spots using UV technology UV & IR - Spectral Ranges UV C B A 140 Visible Near IR 120 Filter Transmission (%) 10 100 8 80 6 60 4 40 2 200 20 300 400 500 600 700 Wavelength (nm) 800 900 1000 Solar Radiation (µW/cm2/nm ) 12 UV & IR - Complimentary Applications UV IR Corona surveys detect voltage related effects resulting from partial insulation failures (typically voltage >6Kv) IR cameras are current related indicators and detect heat generated often by loose connections. Partial discharge technology detect the condition of the insulation! Infrared technology detects the condition of the conductor ! Statements “In most cases the IR inspection is able to identify the failure only in a higher stage of failure development”.( INMR 2009 , EGU –HV Laboratory) “IR camera is not suitable for corona discharge inspection, because the rise of temperature can occur only at extremely high corona or in case of some current load.” (monitoring of HV and UHV overhead lines components with UV and IR cameras” , NMR 2009, EGU – HV Laboratory). UV & IR - Summary UV Thermo vision Detection of UV emission from corona and arcing Sensitive to heat, detection of hot spots Voltage dependent Current dependent Does not require loading of lines Increased load of lines is often required Not affected by solar radiation Affected by intense sunshine Defects often detected at earlier stage of degradation Defects often detected at more advanced stage of degradation Broken strands – three bundled conductor Notes: 1. Corona discharge activity is influenced by the distance of the broken strand to the conductor 2. No noticeable heating for possible IR inspection Bird Caging – Three Bundled Conductor Corona discharge activity No noticeable heating for possible IR inspection Spacer damper - clamp failure and broken strands No noticeable heating for possible IR inspection. Arcing ring horn with ball direction towards the tower leg · The corona discharges occur due to the horn with ball direction towards tower leg. Possible improvement measures are larger ball diameter and/or direction along conductor or outwards tower leg. · No noticeable heating for possible IR inspection. Conclusions UV inspection of conductors and overhead line fittings is a very reliable way for the detection of corona sources with the possibility to identify the large majority of such sources. The corona discharges on conductors and fittings are most reliably detected under dry conditions. “Monitoring of HV and UHV overhead lines components with UV and IR cameras”. INMR 2009, EGU – HV Laboratory. IR Two are better than one UV