Thermal Multimeters

Thermal Multimeters

Thermal multimeters combine the electrical testing ability of a multimeter with the thermal imaging power of a thermal camera. This lets you quickly identify temperature differences that can point to problems.
 

Use the thermal imager to locate hotspots and then test volts, amps, and temperatures with the DMM to diagnose the problem. When repairs are complete you can validate that they were successful with the thermal imager. Download the Fluke Application Note: 5 Reasons you need a multimeter with a built-in thermal imager

Typical thermal imager resolutions with Thermal Multimeters is limited 80x60, so for more serious work consider a higher resolution stand-alone thermal imager. But often the full camera never gets used and stays stored away. With the pocket DMM with thermal imager electricians, automation, electronics, and HVAC technicians are more likely to use the thermal imager.
 

Thermal Imaging Basics

A thermal imager generates an image based on temperature differences. In a thermal image, the hottest item in the scene appears as white and the coldest item as black. All other items are represented as a gray scale value between white and black. They also offer color images to simulate hot (lighter colors) and cold (darker colors) temperatures.
It may take some time to get used to the thermal imagery. Having a basic understanding of the differences between thermal and daylight cameras can help with getting the best performance.

One difference between thermal and daylight cameras has to do with where the energy comes from to create an image. When viewing an image with an ordinary camera, there must be some source of visible light (something hot, such as the sun or other lighting) that reflects off the objects in the scene to the camera. The same is true with human eyesight; the vast majority of what people see is based on reflected light energy. On the other hand, the thermal imager detects energy that is directly radiated from objects in the scene.

This is why hot objects such as parts on engines and exhaust pipes appear white, while the sky, puddles of water and other cold objects appear dark (or cool). Scenes with familiar objects will be easy to interpret with some experience.
Infrared energy is part of a complete range of radiation called the electromagnetic spectrum. The electromagnetic spectrum includes gamma rays, X-rays, ultraviolet, visible, infrared, microwaves (RADAR), and radio waves. The only difference is their wavelength or frequency. All of these forms of radiation travel at the speed of light. Infrared radiation lies between the visible and RADAR portions of the electromagnetic spectrum.

The primary source of infrared radiation is heat or thermal radiation. Any object that has a temperature radiates in the infrared portion of the electromagnetic spectrum. Even objects that are very cold, such as an ice cube, emit infrared. When an object is not quite hot enough to radiate visible light, it will emit most of its energy in the infrared. For example, hot charcoal may not give off light, but it does emit infrared radiation, which we feel as heat. The warmer the object, the more infrared radiation it emits.

Infrared imaging devices produce an image of invisible infrared or “heat” radiation that is unseen by the human eye. There are no colors or “shades” of gray in infrared, only varying intensities of radiated energy. The infrared imager converts this energy into an image that we can interpret.