Electrical maintenance

Thermal imagers from Testo enable reliable detection of thermal anomalies such as overheated lines, contacts or components in all kinds of electrical installations, for example:

  • In low-voltage systems: in control cabinets and electrical components
  • In medium-voltage systems: in electricity generators and transformers 
  • In high-voltage systems: in power transformers and insulators

Using a thermal imager for the inspection is particularly safe and easy, as measurement is basically non-contact and doesn’t interrupt ongoing operations. This allows irregularities and weak spots to be detected, before a defect or an accident can even occur. Thermography therefore plays an essential role in ensuring efficient, safe and interruption-free system operations.

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Low voltage

Application image for thermography in a control cabinet

In electrical installations or cables, increased temperatures are always an indication of faulty operation caused, for example, by:

  • an overload
  • an impending malfunction
  • a defect that already exists

For inspection and maintenance, thermography is your tool of choice. Non-contact measurements can be performed from a safe distance without having to interfere in operations. If an anomaly is detected, countermeasures can be taken quickly.

Thermography switch cabinet

Thermography of electrical components

The primary factor when performing a thermographic assessment of electrical components is the heat distribution within the individual components. This provides information about

  • proper functioning
  • the capacity level reached
  • the reliability and service life to be expected

A thermal imager allows fast, reliable assessment of a component’s operating state. If unexpected heat distribution indicates a malfunction or imminent end of the service life of a component, repairs can be scheduled before the entire system breaks down.

Thermal image electrical component
Thermal image switch cabinet

If many similar systems and control cabinets are regularly checked, this takes up too much time unnecessarily for the systematic storage of data. SiteRecognition technology from Testo 

  • automatically recognises the measuring location 
  • automatically stores the thermal images in defined folders
  • allows direct comparison with previous inspections

SiteRecognition not only relieves you of time-consuming, error-prone administration and archiving. It also offers you a simple and quick overview of all measurement data and the temporal development of the individual measuring points – conveniently and securely on your PC.

Medium voltage

Thermal image of transformers


Transformers and machines Depending on the type of insulation, the connections, cores or insulation in components of medium-voltage installations such as transformers can be inspected for thermal irregularities.

High voltage

Overhead power line
Thermal image of an overhead power line

Overhead power lines

Overhead power lines and substations The electrical connection points and insulators for overhead power lines in substations or the overhead power lines of high-voltage systems can be checked for maintenance purposes. Typically, these locations are difficult to access. Many points can be conveniently checked thermographically using a super telephoto lens.

Practical guide on thermography in preventive maintenance

Thermal imager guide
Find out on 16 pages how you can use thermal imagers to optimize processes and plant availability.

Video: Electrical maintenance with Testo thermal imagers

Cables, contactors and fuses: Thermal imagers in electrical maintenance

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