Video: IRDL700

Video transcript

A thermal camera meant to be used every day, by anyone on the team. What it measures, how it is operated, and what makes an inspection reliable. Preventive thermography only works if it is done often. Transformer substations, switchgear and industrial plant need a round every few months, and a camera that needs a specialist every time does not get used. This one is built to be picked up and used. The detector is an uncooled microbolometer of 384 by 288 pixels, with a thermal sensitivity of 600ths of a degree.

It measures from minus 20 to 500 degrees, and weighs 1.69 kilograms. The infrared lens looks forward. On top, a colour screen of 640 by 480 turns on its mount, and at the back there is an eyepiece for bright light. The controls sit on the side, under the thumb, and the strap holds the camera in the right hand. Operation comes down to a single button. Focus is manual or automatic, the electronic zoom goes from one to 8 times,

and 9 palettes change how the image is shown. The laser pointer marks exactly what you are measuring. The standard lens covers 16 by 12 degrees and focuses from half a metre. For distant targets, such as lines and bushings, a telephoto lens narrows the view. For close work, a wide angle lens fits a whole panel into one image. Two options change how it is used. The lenses screw on in place of the standard one. And a remote screen, on a cable or clipped to the grip,

lets you hold the camera where it has to be while you watch the image where you can see it. What is it looking for? Heat where there should be none. A loose or corroded connection has resistance, and current through a resistance becomes heat. Overloads and unbalanced phases show up the same way, and all of them appear before the failure. And here is why load matters. The heating of a bad contact grows with the square of the current.

At half the current, it produces only a quarter of the heat, and a real defect can pass for normal. Inspect at normal load or above, and note the load with every image. The camera also needs to know what it is looking at. Set the emissivity from 0.01 to one, or choose the material from the list. Enter the distance, the humidity and the ambient temperature, and the background and atmospheric corrections are calculated automatically. To compare, measure the same point on each phase.

Here, 3 areas sit on the top of 3 insulators, one per phase, each with its own temperature. Up to 10 points and 5 areas can be placed, with a profile line, isotherms and a temperature difference. The difference between phases, under the same load, is what decides the priority. A small difference is logged and watched. A clear one is scheduled for repair. A large one, or one that is growing between rounds, needs action now.

The limits come from your maintenance standard. A round, step by step. Switch on and set the emissivity and distance. Point with the laser and focus. Scan the equipment. Measure the suspect point and its reference. Save the image, and record a voice note of up to 40 seconds. Images go to the internal flash memory or to the SD card, up to 5000 of them, each with 14 bits of thermal data. A spatial filter and frame averaging clean up noisy scenes,

and everything, including the voice notes, is transferred to a PC over USB. On the PC the analysis continues, without the limits of a small screen. Points, areas, lines and isotherms can be adjusted, the palette and the emissivity changed, the voice notes played back, and the inspection report built with the thermal and visual images. The battery gives two hours of continuous work, and an external supply of 10 to 15 volts keeps it running longer. It works from minus 15 to 50 degrees, sealed to IP 54. The laser is class two:

never into anyone's eyes, and never point the camera at the sun. In the Amperis range, the IRDL700 is the straightforward choice: a 384 pixel detector, interchangeable lenses and remote screens, at a lower cost. Thermal imaging, from Amperis.