Testing high-voltage plants with thermal imagers from Testo

Thermography increases reliability of supply.

As an integral part of electrical supply networks, high-voltage plants such as substations must ensure as uninterrupted a supply of electricity as possible due to the high availability of their electrical systems. A malfunction or interruption of the electrical grid is often preceded by thermal warming caused by electrical resistance. This must be localized, evaluated and if required, the time frame for a repair determined.

Using the thermal imagers from Testo, thermal warming can be tested without contact and from a safe distance, without endangering the user or needing to shut down the system.

High-voltage systems
Thermography high voltage

Checking the clamp connection on the isolator

The challenge

Most symptoms of wear, material fatigue or cable rupture in the transmission of electrical current are preceded by thermal warming due to increased resistance. If this resistance becomes to high, the heat development destroys the component, with the possible result of a power cut. The objective of maintenance work is to obtain an overview of the switchgear which is comprehensive as well as detailed – including all circuit breakers and power switches, converters, insulators, screw fittings, cables or other connections.

A further challenge lies in the cooling oil of the transformers. Due to eroded insulation, slurry can occur here, which is deposited in the cooling ribs. The blockage of the through-flow in the affected cooling ribs initially compromises the cooling, and in the worst case can result in the failure of the complete cooling function of the transformer.

Thermography current

Thermal image of the current loop on a dead-end tower

The solution.

Thermal imager testo 883

With the testo 883 and testo 890 high-resolution thermal imagers, these potential sources of error can be quickly and precisely identified before they become serious problems endangering the reliability of supply. The standard lens of both imagers quickly provides a meaningful overview of the overall status of the system being tested.

The telephoto lens of the testo 883 or the SuperTele lens of the testo 890 are recommended for precise thermography of distant measurement objects. This accessory for instance means that the smallest measurable object (an object that it is not just possible to detect but whose temperature can also be reliably measured) is 20.1 mm for the testo 883 with the telephoto lens: For the testo 890 with the SuperTele lens, it is 5.7 mm (measurement distance in both cases: 10 m). For example, this allows the smallest cable ruptures or temperature increases in circuit breakers to be evaluated from a safe distance.

SuperTelephoto lens

The testo 883 kit includes both the thermal imager including standard lens and a exchangeable telephoto lens. Apart from this, the imager also convinces with its handy and easy-to-grip design and convenient operation via touch display and joystick, as well as the long battery life. By transmitting a live stream to a mobile end device with the Thermography App, which can also be used to operate the testo 883 thermal imager, thermographic recording of hardto-reach objects is easy.

The testo 890 scores points with its large rotating and swiveling display, which enables overhead recordings. In combination with the ergonomic twist handle, safe handling even in hard-to-reach places is no problem.

Finally, the status of the system being tested can be professionally documented using the intuitive evaluation functions and easy reporting of the testo IRSoft analysis software.