Should compressed air plant be included in an electrical thermography survey?

Yes. Air compressors are some of the heaviest motor loads on a manufacturing or food site and often run around the clock, but they load, unload and start with demand. The supply, starter or drive panel should be imaged while the compressor is running loaded, with the load recorded for each image, and the compressor’s own process heat kept out of the electrical findings.

Why compressors belong in the survey

When the compressed air stops, so do the pneumatic actuators, packing machines and valves that depend on it. Compressor houses are often a separate room or building at the edge of site, and they can drop off a survey route that follows the production floor. Including them means the plant every line relies on gets the same check as the lines themselves.

What to include

The dedicated supply from the main switchboard and the incoming isolator
Each compressor’s starter or variable speed drive: incoming, contactor and outgoing terminals
The sequencer or master controller supply where there is one
Supplies to dryers, condensate drains and the compressor house ventilation fans

Catching it under load

A fixed-speed compressor cycles between loaded and unloaded running, and the current it draws changes within seconds. The thermographer images each connection while the machine is loaded and records the load at the time. A variable speed machine follows demand, so its load at the time of each image matters just as much.

Most compressor houses run one machine as duty and keep another as standby or lag. A standby compressor that is not running shows nothing useful on camera. The survey is planned with the site so the duty is rotated, or the report lists the standby machine as not imaged under load.

Heat that isn’t an electrical fault

A compressor house is a hot room. Discharge pipework, aftercoolers and oil separators run hot by design, and their heat reflects off bare metal and enclosure doors near the panels. Drive heatsinks are warm in normal running too. The thermographer changes the camera angle to check that a hot spot stays with the component, compares each connection with a matching one under the same load, and gives the difference in °C. The room temperature is recorded, and the report says what was measured and where. It does not diagnose the cause from the image.

What the report gives you

Each finding carries the equipment reference, the measured temperature, where it was taken, the reference it was compared with, the difference in °C and the load at the time. Ti Thermal Imaging issues the report the same day. Ti inspects and reports; your maintenance team or electrical contractor investigates and carries out any work.

Why detail matters

On a London data centre build, commissioning thermography by our team found 16 busbar sections reading above 80 °C under test load, the highest 103.5 °C at a tap-off unit. Each one showed because the equipment was carrying load when it was imaged. A compressor is the same: image it loaded, or the survey cannot see what matters.

Frequently asked questions

Does the compressor need to be stopped?

No. Thermography only works on energised equipment carrying load, so the compressor keeps running and the site’s authorised person opens each panel under the site’s permit.

What about the standby compressor?

Ask the site to rotate the duty during the visit. If that is not possible, the report lists the standby machine as not imaged under load.

How often should compressed air plant be surveyed?

Most sites include it in their annual electrical thermography survey, alongside the production lines it supplies.