- Corona Interpretation -
Insulator coatings…
- Corona Interpretation -
• The CoroCAM Team – Pretoria, South Africa
• Design - Production – Marketing - Service -
- Corona Interpretation -
•
Corona & Corona Count in box, GPS, UV Gain sets blob size, UV Filter
settings, date & time, right side displays Auto Focus, x1 visible, C filter
•
Note there are multiple colors to select from so the display corona will
contrast with background colors
•
There are 4 UV count update rates to select from, normal is 2 seconds,
if flying 35+ mph and recording use faster time.
- Corona Interpretation -
• Corona images, can be deceiving, try not to overlay
objects, here the tap is in-line with an insulator, Which
has the corona ?
• Likely the unused tap sharp corners.
- Corona Interpretation -
• Corona – example's of tree proximity
causing corona on insulator, defective
hardware, defective insulator, lack of
corona ring.
- Corona Interpretation -
• Corona can appear as random discharges due to
wind, movement of hardware,...something that
causes the “gap” to go critical and cross the
breakdown threshold of the nitrogen in the air. The
electric field intensity.
- Corona Interpretation -
•
Always search at 100% gain, or as
high as possible, if there is “background”
noise – electric arc welding, flare stacks,
some cooling towers, some propane fork
lift engines, – try to change the viewing
angle to minimize the background noise, UV also
reflects off moisture droplets, cooling tower plumes, ...
- Corona Interpretation -
• Corona images can be stitched together.
• Tree branches, defective insulators &
hardware, lack of corona rings, all
contribute to this.
- Corona Interpretation -
•
Corona in the middle of an insulator string, may be the result of damage, bird droppings,
punctured end insulators, never a good sign.
•
Corona inside the “protected area” of the corona rings means the corona rings aren't
correct. I have seen corona rings installed backward, the noisiest thing in the substation,
within 2 years after “temporary” installation the 500KV NCI was a different color on 1/3 of
its length.
•
Corona is the result, of a bad design likely (the clamp) inside this line marker (does not
have a corona ring.)
- Corona Interpretation -
•
A pair of interesting examples of long-term corona damage.
•
The woven link has many fine wires, when corona damages the strands it may look OK, but
actually crumble.
•
The insulator hardware has corona on the cotter pin, and if there is no rain for weeks, the
corona powder can accumulate on this insulator or another causing flash-over potential
when wetted.
•
The other part of the insulator hardware corona is what you don't see, the corona next to
the NCI insulator is continuously prematurely “aging” the insulator with Ultraviolet light,
Ozone, the Nitric acid contamination, ...
- Corona Interpretation -
• Corona is where you find it, this is why the zoom capability of the
CoroCAM 504 and the Corona 350 gimbal stability is so important to
be able to isolate if there are lines that are too close to each other,
trees growing into the right-of-way, gun shot damage causing
strands to stick out, or just thermal growth causing strands to get
loose.
- Corona Interpretation -
• Corona causes, this line is too small in
diameter for the applied voltage, not
uncommon when in substations to connect
to a PT, where there is no real current flow.
- Corona Interpretation -
• The leading edge or start of a fire can be seen with a
corona camera at much greater distances then with
infrared. The heat of the fire can be seen with
infrared. The flames with visible camera.
- Corona Interpretation -
• Corona interference source, florescent lamps in a roadside
sign.
• Also note camera gain and filter setting, GPS coordinates,
date/time, auto-focus, x1 zoom, C Filter is on, “corona/UV”
count in lower right of box.
- Corona Interpretation -
•
Corona on a NCI insulator is never a good thing to see, it is either
damaging the insulator or indicating where the damage already is,
when the damage gets critical there is arcing, followed by a dropped
line when the insulator structurally fails.
•
The right pic shows the reason corona rings are needed, there is no
hope for this insulator.
- Corona Interpretation -
•
The left picture shows a minimum corona problem due to: a cap
broken loose from the surge arrestor, or a wire out too far.
•
The right picture shows the arrestor alongside is destroyed.
•
Always try to get best resolution to define “all” of the problems.
- Corona Interpretation -
•
Corona is where you find it, understanding why it is there is your job.
•
This 345kV transmission line has line spacing problems, long spans
without spacers, and the conductor is also too small for the altitude
(and is always in corona), if the conductor is “dragged” across the
ground it will accumulate debris, scratches, that will also cause
corona. New conductors can have “die grease” used when making the
conductor that will “wash out” of the conductor over a few months of
regular rainfalls.
Corona Interpretation
• Created by Dan Ninedorf
• CoroCAM corona camera distributor – North
America, Puerto Rico, Guam
• Ox Creek Energy Associates Inc
• www.specialcamera.com
• Cameras@maqs.net
• 800-531-6232 rings into cell 920-255-5510
• Copyright 2013 Ox Creek Energy Assoc Inc.