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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