Not Your Average Camera

21 October 2020

We’ve got good news and bad news.

The bad news – spot infrared thermometers only give you the temperature at a single spot.

Given increased health and safety measures, this is not necessarily bad news for many. These spot IR thermometers are super popular right now for taking contactless temperature readings on people, which is actually a really helpful tool for many offices, businesses, and healthcare facilities.

For electricians though, you can do better.

The good news? Thermal imaging cameras give you the whole entire picture.

And, they’re a super effective method for finding problems – or soon to be problems – across a wide range of applications, including:

  • Troubleshooting electrical problems
  • Detecting heat flow
  • Checking thermal insulation
  • Lubrication and HVAC
  • Building Insulation Inspection

We should also note that thermal imaging camera aren’t just for electricians and maintenance techs too. Firefighters use thermal imagers to find and rescue people in thick smoke, law enforcement officers utilize them for surveillance and suspect location, and they were originally created for military use during the Korean War. Who knew?

Why are they so effective?

Well, they provide an image (obviously), which gives you the temperature differences of the object you’re looking at, rather than just the average temperature of the object.

How do thermal imagers work?

First, you should know that all objects radiate infrared (IR) energy. While we can see things in visible light, this is really only a small part of the total electromagnetic spectrum. Comparatively, IR radiation takes up way more space on the spectrum than visible light.

And the temperature of the object and the emissivity – or the ratio of energy radiated by an object to the energy emitted by a perfect radiator at the same temperature – will determine how much IR energy each object radiates.

Things like wood, water, your skin, clothing or other fabric materials, plastic, paper, and painted surfaces are really good at radiating energy, so they have high emissivity values. Your thermal imager is going to way better at measuring the temperature of these kinds of objects more accurately too, so keep that in mind.

Surfaces with a low emissivity – like oxidized metals – make it much harder for your thermal camera to get a good (reliable and consistent) image with the correct temperatures. So, if you’re dealing with lower emissivity objects, keep in mind that your potential for error is higher too.

Also, it’s important to remember that emissivity has nothing to do with color. If you put a bunch of different colored stickers on a surface, they’re all going to show up as the same temperature.  If you’re interested in learning more about specific emissivity of various objects, check out the complete table of emissivity values here.

And your thermal imager is going to measure that IR energy, calculate a temperature estimate, and display an image on the screen. By the way, a thermal camera can’t see “through” an object. It simply detects IR radiation from the surface of an object. A thermal camera also doesn’t care if you’re taking the picture in visible light – like night vs. day. Either way, you’re going to get the same thermal image.

You have two options for how you use that picture. You can either look at the temperature readings across various positions on the image and compare the differences in temperature on the display. Or, you can take that picture and compare it to a picture of a similar load under alike conditions.

Why use a thermal imager?

Well, at the end of the day, it’s another great fault-finding tool for electrical contractors to have in their truck, and many see it as a complimentary test to low resistance testing. Thermal cameras are typically lightweight too, easy to use, and certain advanced models can store images, as well.

There are also some clear benefits.

  • You don’t have to power down the entire system to take a thermal image.
  • You can identify multiple issues – including loose terminal connections, unbalanced loads, and cable hot-spots – at the same time
  • There are lots of non-electrical applications too, including: motor bearings, hot water and heating problems, or unwanted heat loss.
  • Hot spots can be seen immediately, versus traditional IR guns, which just give you the average temperature of an area.

Who can use a thermal camera?

If you’re looking for an extensive list – including everything from police surveillance to detecting unwanted pests, check out this list of thermal camera applications.

Since this is an electrical testing blog though, we’re just going to look at those applications.

For electricians, maintenance technicians, engineers, and the like, thermal cameras are great for…

  • Identifying electrical defects on printed circuit boards
  • Quickly determining which circuits on a switchboard are using excessive power
  • Locating hotspots on equipment before they cause unplanned downtime and irreversible damage
  • Finding electrical defects on solar panels
  • Taking overheated motors offline for maintenance before they completely fail
  • Identifying overheated components (ie. substations, transformers, etc..)

Clearly, the possibilities are endless when it comes to thermal imaging.

So, are you ready to add a thermal camera to your toolbox? Check this out.