The Importance of Design Integrity for Substation Transformer Foundation

December 13, 2019

Pedestrians don't pay any attention to electrical transformers. Maybe that's because they're locked up behind barbed-wire fences or brick walls, for the safety of those same pedestrians, of course. They're actually interesting pieces of equipment. Filled with twin coils of wiring, step-down or step-up transformers use mutual inductance magnetic fields to perform their power transforming labours. Apart from anything else, that aspect of transformer technology also makes them quite heavy.

Supporting Heavy Substation Transformers

So, what do the internal workings of a distribution centre transformer look like? Well, there are heavy copper windings inside their sealed housings. They're insulated from one another, which is all well and good, but the insulation adds more weight to the design. Then there's a laminated steel core. The windings are wrapped around that core, which is also heavy. Incidentally, those windings produce heat. The core laminations eliminate stray eddy currents, but there's still that thermal build-up to handle. To offset the heat, oil-filled housings carry the thermal energy away and discharge it through sets of air-cooled equipment fins. But, just one more time, the oily inner conditions add even more weight to an already heavy structure. Supporting that weight, a robust foundation opposes the equipment's soil-crushing load.

Installing Augmented Substation Foundations

Maintaining design integrity, a site project manager liaisons with the transformer manufacturer. Information is provided about the equipment so that an order can be put in for a corresponding set of concrete-reinforced building blocks. Is this a three-phase device loaded with copper coils and a steel-laminated core? If it's filled with oil, what's the net weight of the equipment, including this liquid-viscous, heat mitigating fluid? Before that load-bearing concrete base is installed, a soil analysis service should be arranged. If the existing ground won't support the equipment and its concrete base, some foundations strengthening work will need to be carried out. The ground might need to be graded or compressed, then there could be a layer of gravel to place on top of the soil after the concrete footings and soil grading work is done.

There's a second problem to attend to when installing substation transformers. After the ground compaction, backfilling and grading services are all complete, the concrete is poured. The base is designed to perform as a high-strength equipment platform, so it'll handle great quantities of downward-forcing compressive force, as imposed by the steel core and copper windings, plus that heat-dissipating oil. And that takes us nicely onto the second problem, which has nothing to do with housing weight. This is an environmental issue. If the oil leaks, it could harm the soil and enter the local water table. With rounded gravel aggregate filling the sealed transformer pits, the site foundations gain an element of environmental incorruptibility.

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