Video: CoroCAM 7HD

Video transcript

The CoroCAM 7HD: a corona camera built around two channels only, ultraviolet and high definition visible, and around the inspector who has to hold it all day. A corona discharge on a line or in a substation is small, often far away, and invisible to the eye. The inspector needs to find it, then see exactly which part it comes from, without going any closer to live equipment. Why it works in full sunlight. The ozone layer absorbs the sun's ultraviolet below about 280 nanometres,

while a discharge still emits there. The camera only looks in that dark band, so any light it sees comes from the discharge. In figures: an ultraviolet sensitivity of 2.05 times 10 to the minus 18 watts per square centimetre, certified at one picocoulomb at 15 metres, in solar-blind and non solar-blind mode. And a full HD visible channel with 30 times optical zoom. What sets the 7 HD apart is focus. No thermal channel:

only ultraviolet and visible, with the long zoom to read the detail of a fitting from far away. A motorised filter for night and indoor work. And a body designed for long days in the field. From the front: one large window for ultraviolet and visible, the flashlight and the laser aperture below it, and the swing-out lens cover. The side keys sit on the grip, the viewfinder on top, and the screen folds out to the side.

From behind: the screen and the viewfinder, which shows the same image when the sun is too bright for the screen. The instruction sticker lists every key. The rubber flaps cover the connectors, and the battery bay opens with a clip. Charge the batteries for at least 10 hours first. Battery in, with the pin holes facing inside the camera, then the micro SD card. Hold power for one second. The camera is usable in 6 seconds and ready to record within 60.

For a fast GPS lock, leave it on with the booster antenna for 10 minutes the first time. The main keypad is under the right thumb. Power, the 4 arrows around SELECT, which switches between the ultraviolet and the visible channel, separate keys for video and still pictures, and MENU. The side keys do the rest: zoom, focus near and far, and the laser, which fires only while the key is held. ALT gives every key a second job.

ALT then record saves a UCF file with the raw ultraviolet image, ALT twice opens the info screen, and ALT with MENU the setup. The grip rotates to whatever angle is comfortable and the strap holds the hand, so the camera can be used from different stances, at arm's length on the screen or up at the eye on the viewfinder. The picture is the visible image with the ultraviolet overlay on top. Top left, the gain and the count, the ultraviolet intensity in the sampling area. In the centre, the warning flags.

A no UV flag means discharges could be missed, for instance when digital zoom takes over. Four settings make faint or noisy scenes readable. Gain sets how much the intensifier amplifies. The threshold hides pixels below its level, 40 per cent by default. Long integration adds up to 32 frames, and noise reduction averages them. Then make the discharge easy to see. At 100 per cent opacity the blob is solid, best for searching.

Near zero it is transparent, best for showing the hardware behind it. Six preset colours and a 100 hues keep it in contrast with any background. At night or indoors there is no sun to block. Non solar-blind mode moves the filter out of the way with a motor and widens the band, for more sensitivity. The flashlight lights the scene, and the visible channel has a low light mode, defog and wide dynamic range. Every file keeps its context. Pictures, video and UCF files go to the micro SD card,

with the settings and the GPS position. Distance, humidity, temperature, pressure and wind are entered by hand. A 3 digit series number groups all the files of one fault. Safety and care. The laser is class 3 R: never at people or vehicles. Never aim at the sun. The sealed body builds up heat, so use the mains adapter for long sessions and keep the base plate free. Clean the window with a brush and a damp lens tissue, and update the firmware from the SD card.

Corona inspection, from Amperis.