1. Misinterpreting reflections
In the visible world, we see reflections from many surfaces, the most common example is with a mirror. Reflections also happen in the world of Infrared Radiation.
Polished and shiny surfaces, metals being the best example, will often reflect more. Stand in front of a copper connection and chances are any hotspots you see on the image will be your own body heat reflecting back at the camera.
This is one of the most common mistakes we see, with reflections being incorrectly reported as a fault.
2. Ignoring thermal gradients
Reporting software for thermography surveys has become very powerful, however this does not mean the software will do all the work for you.
As a camera operator, you need to understand how thermal gradients link to faults and use these to correctly identify problems. This may seem like a no-brainer, but we have seen real world thermography reports where an obvious connection fault has been ignored and signed off as acceptable.
3. Failing to understand the impact of emissivity
Emissivity is the capacity of an object to emit infrared radiation. This goes hand-in-hand with reflected radiation. Using the wrong emissivity setting results in false temperature readings.
There are several additional factors that can affect emissivity, therefore understanding what emissivity is and how to correctly account for it will ensure you do not make this mistake.
4. Assuming the camera will do all the work
Many thermal cameras, especially the low cost models, are described as point-and-shoot. This does not mean the camera will do all the work for you. As the camera operator, you are responsible for ensuring the settings are correct when carrying out a survey and compiling a report.
Incorrect settings lead to incorrect results.
5. Not opening the panel door
Thermal cameras are not x-ray cameras! They will only detect the radiated heat from the surface of the object you are looking at. Without a direct line of sight, most faults will be missed.
Health and safety restrictions may prevent panel doors from being opened, so in this scenario other alternatives may need to be investigated, such as infrared viewing windows.
6. Not surveying under load
Again, this may seem like a no-brainer, but this is a mistake that is made. Without load the system will not generate any heat and faults will not be visible.
With this brief article, we have looked at some of the more common errors made during an electrical thermal survey. Failure to understand the basics of thermography and carry out the survey correctly will result in an incorrect report being issued to the client.
If an obvious fault, such as a loose connection is missed and signed off as being ok, where do you stand if that connection then causes a fire? Who will your client sue if the insurance company looks at the thermography report and decides not to pay out?
How can you avoid making these common mistakes?
As with any specialist equipment, proper training will always ensure you get the best out of it and use it correctly. At Instrotech, we run a dedicated 1 day training course which covers the basics of electrical thermography. The training course is written by the ITC and covers the following key subjects:
- Basics of Thermography
- Basics of Emissivity
- Reflected Apparent Temperature
- Camera Handling & Setup
- Basics of Heat Transfer
- Radiative Transfer
- Electrical Systems
- Important Properties of Materials
- Most Common Problems
- Case Studies
- Common Mistakes
- The Right Approach
- Practical Labs & Report Generation
If you are carrying out thermal surveys, or if you want to start doing this for your clients, why not book a place on our next training course, or if you have a group of people to train, we can come to you. Call us on 01923 442244 for more details.
