What should an electrical thermography survey cover at a quarry or aggregates plant?

It should follow the power from the site intake and main switchboard to the MCCs and VSD panels for the crushers, screens, conveyors and washing plant, plus pump panels and outdoor distribution. Everything is imaged live while the plant is crushing at full output, with panels opened by the site’s electrician and readings taken where dust and sunlight won’t distort them.

Survey while the plant is crushing

A crusher MCC tells you little on a maintenance day. The connections that matter only carry their real current when the primary crusher is taking feed and the conveyors are loaded. So the survey is booked for a full production day, ideally at the busiest part of the shift. If the site runs a reduced winter output, book before output drops (see best time of year to survey).

What the scope should include

Intake and main switchboard: LV tails from the site transformer, main incomer and outgoing feeders.
Crushing and screening MCCs: primary and secondary crusher starters, screen drives and their VSD panels (see MCCs and VSDs imaged while running).
Conveyor drives and control panels along the plant, including stockpile and loadout conveyors (see conveyor control panels).
Washing and water plant: pump panels for washing, dewatering and settlement lagoons.
Compressed air where the plant uses it (see compressed air plant).
Outdoor distribution: feeder pillars, site boards and supplies to cabins and workshops.
Weighbridge, office and lighting boards, which are quick to add on the same visit.

The survey covers electrical panels and connections. Motors, bearings and gearboxes are mechanical checks and sit outside this scope.

Traps a good thermographer avoids

Dust. A layer of dust on a connection changes what the camera sees. Where it can be done safely, the panel is opened so connections are imaged directly, and any reading through a dusty surface is noted as a limitation.
Sun on outdoor kit. Solar gain on a south-facing panel can look like a hot spot. Outdoor boards are compared like for like, and imaged early, late or on an overcast day where the site allows (see outdoor equipment in UK weather).
Heat from the process. A panel next to a drive or a dryer can read warm all over. That is not a finding. What matters is the difference between matching connections, phase to phase.
Drives that start and stop. Some conveyors and pumps cycle. Each circuit is imaged while it is running, and the report records it.

Working on a quarry site

The thermographer follows the site induction, PPE and vehicle rules, and works with the site’s electrician, who opens panels under the site’s own permit system (see who opens the panels). Routes between plant areas are agreed on the day so the survey keeps clear of mobile plant.

What the report gives you

A same-day report that locates each finding by panel, circuit and phase, with a thermal and visual image pair, the measured temperature, where it was taken, the difference in °C from the matching reference and the running state at the time. Ti inspects and reports. The site’s electrical contractor investigates any finding with the equipment isolated.

Why load matters

Load is what makes a weak connection show. 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. The same principle applies to a crusher MCC: survey it when it is working hardest.

Frequently asked questions

Does the plant have to stop for the survey?

No. It needs to be running. Thermography images energised equipment on load.

How often should a quarry be surveyed?

Most sites survey annually, and again after major plant changes, such as a new crusher or a rebuilt MCC.

Can several quarries be covered under one programme?

Yes. One asset list and one report format across sites makes year-on-year comparison simple (see multi-site programmes).