Video: TC4/TC8

Video transcript

Two light, rugged thermal cameras for the daily maintenance round. How they differ, why they survive a fall, and how to turn a hot spot into a decision. A maintenance round covers dozens of panels, motor control centres and distribution boards in a shift. The camera travels in a tool bag, goes up ladders and gets knocked. It has to be light, tough and quick to use, or the round does not get done. The series has two models on the same body.

The TC4 has a detector of 160 by 120 pixels. The TC8 has 384 by 288, a finer spatial resolution, and a range that extends to 2000 degrees. What the pixels mean in practice. The TC8 has almost 6 times as many, so a small terminal, or one at a distance, is covered by more of them. The TC4 is enough when you can get close to the target. Both are built to be dropped.

The sensor technology withstands a fall from two metres, a shock of 25 G and a vibration of two G, and the body is sealed to IP 54. The whole camera weighs less than a kilogram, with a side handle and a tripod thread. Everything is done on a 3.6 inch touchscreen. The thermal image can be fused with the 3 megapixel daylight camera, and two LED lights brighten a dark cabinet. The menus are icons: measurement, image, camera, storage and connection settings.

The lens covers 25 by 19 degrees and focuses from 10 centimetres. That suits panel work: get close and fill the image with the terminal you want to measure. Focus is manual, and it is part of the measurement: a blurred terminal reads cooler than it is. What the round is looking for is heat that should not be there. A loose or corroded terminal has extra resistance, and current through it turns into heat.

An overloaded cable runs warm along its length, and a phase carrying more current stands out from the other two. Before reading any number, set the emissivity. Bare aluminium radiates only a 5th of what a black surface would, and it mirrors whatever is around it. Paint radiates almost everything. On shiny metal, measure a painted or oxidised part nearby, or change your angle to spot reflections.

A hot spot also needs current. The heating grows with the square of the load current, so a round made at light load hides faults. Plan the round when the installation is working normally, note the load, and compare only under similar conditions. To decide, compare. Measure the suspect terminal, then the same terminal on the other phases, under the same load. The temperature difference sets the priority:

small, record it and check again; clear, plan the repair; large or growing, act now. The limits come from your maintenance standard. On screen: up to 5 points, 5 areas with the maximum, minimum and average, and two lines with a temperature profile. Isotherms and a temperature difference, and an alarm by voice or colour when a limit is passed. One panel at a time. Open it only as your site procedure allows. Scan the whole panel. Get close to what stands out, and focus.

Compare with the other phases. Save the image, with a voice note of up to 60 seconds. Images and video are saved on a micro SD card of 8 gigabytes, or up to 32. Both the JPEG images and the H₂ 6 4 videos keep the original radiometric data, and the thermal and daylight images are saved linked together. Getting the work out: by mini USB, with the images and their measurement data. By network, as live images and video. By Bluetooth, for a headset or an RS-232 link.

And through the video output, to a monitor. The lithium battery gives 3 hours of continuous use, with automatic sleep and shutdown, and charges from 12 volts. Both cameras work from minus 15 to 50 degrees. The laser is class two: never into anyone's eyes. And never point the camera at the sun. In the Amperis range, the TC4 and TC8 are the lightest and the most rugged: the cameras to carry on every round. Thermal imaging, from Amperis.