Transcript Corona

Ofil’s proprietary material
Cannot be used without Ofil's explicit permission
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Partial Discharge and the Corona Phenomenon
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Solar Blind Imaging
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Corona Inspection as a PDM tool in hand
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Faults
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Indications
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Methodology
Ofil’s proprietary Material | 2011
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Detect PD corona & arcing - in daylight
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Diagnostic tool
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Condition monitoring of critical components
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Perform predictive maintenance
Ofil’s proprietary Material | 2011
 Trigger
localized high e-fields
that exceed a critical value
20-30 kV/cm
 Generates
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Audio noise
Corrosive materials (O3, NO-)
Radio and TV interferences
UV - corona
In the presence of a strong E-field
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Free electrons accelerate
Collide with air molecules and ionize them
Additional electrons are released
Photons are released with recombination
Procedure repeats itself
UV Ph
e
UV Ph
-V
e
e
+
e
E field
e
+
e
+
e
e
UV Ph
Ozone blocks Solar UV Signals
10
IR
VISIBLE
120
100
8
80
6
60
4
40
2
200
20
300
400
500
600
700
Wave length (nm)
800
900
1000
Solar Radiation (µW/cm2)
Filter Transmission (%)
UV
C B A
Goal: Collect UV events & superimpose
Imaging
“Black Box”
input - scenery
output - screen
Ofil’s proprietary material
Cannot be used without Ofil's explicit permission
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External – surface
Line of sight
Voltage dependent
Any weather conditions
Indicator & Actor
Fault early stage detection
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Corrosion and erosion
Pitted cement
Hydrophobicity compromise
RFI/TVI
Case 1: A US Government Licensed Radio Amateur Operator: The receiving
equipment was reading a noise level of some 30 dB over S9 (Signal
strength is measured in S-units from S1 to S9) and the noise blanking system of the
receiving equipment could not eliminate the noise.
RFI/TVI
1. Corona during hazy day
2. Camera depicts the exact corona
arcing location
3. Lineman from EMC takes down the
faulty arrestor
Case 2:
USA
1. RFI at FAA Control Tower during
wet weather
2. The source: Bad grounding on
4.16kV, 12.47kV, 115kV insulators
Case 3:
Czech Republic
1. RFI at Czech Radio Telecomm
Authority experienced TVI
2. The source: Pin of a ceramic
insulator was wrongly installed
Tracking & loss of hydrophobicity
Brittle fracture:
corona cameras can clearly show surface
discharge that exists on insulators with
housing imperfections in order to avoid
catastrophic failure.
 Faulty designs
 Faulty installations
 Poor material
 Existing processes
 No corona ring
 Grading ring installed backwards
 Cracked insulator
 Wrong design
dX
Corona- where?
Critical
component?
Yes
No
No
Critical
location?
Yes
No
Material type
Can it
be damaged by
corona?
Events per Minute
Yes
AN, RI, TVI
concern?
Yes
Repair or replace
ASAP
No
Low<1000
Monitor for
additional signs
Corona
intensity?
1000<Medium<5000
High> 5000
Repair or replace
ASAP
Schedule repair or
replacement
THANK YOU