UV-IR complimentary technologies

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“A picture is worth thousand words” No corona on IR picture Live End Corona Dead End Corona Corona spots using UV technology

No corona on IR pictureCorona spots using UV technology “A picture is worth thousand words”

UV & IR - Spectral Ranges

IR cameras are current related indicators and detect heat generated often by loose connections. Corona surveys detect voltage related effects resulting from partial insulation failures (typically voltage >6Kv) Infrared technology detects the condition of the conductor ! Partial discharge technology detect the condition of the insulation! UV & IR - Complimentary Applications

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 UVThermo vision Detection of UV emission from corona and arcing Sensitive to heat, detection of hot spots Voltage dependentCurrent dependent Does not require loading of linesIncreased load of lines is often required Not affected by solar radiationAffected by intense sunshine Defects often detected at earlier stage of degradation Defects often detected at more advanced stage of degradation

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 Broken strands – three bundled conductor

Bird Caging – Three Bundled Conductor Corona discharge activity No noticeable heating for possible IR inspection

No noticeable heating for possible IR inspection. Spacer damper - clamp failure and broken strands

· 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. Arcing ring horn Arcing ring horn with ball direction towards the tower leg with ball direction towards the tower leg

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.

Two are better than one