- 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.