How Power Transformers Are Unloaded, Dragged & Placed on Plinth
Power transformers are among the heaviest single loads moved on land — a 50 MVA unit weighs around 60–70 tonnes, and grid-scale 500 MVA transformers several times more. They are also fragile in a very specific way: the active parts inside the tank are not designed for shock loads. That combination is why transformer unloading is a specialist trade, not general labour work.
Unloading without a crane: the jack-and-skid method
At most substation sites, transformers are unloaded without any crane. The sequence: hydraulic jacks (50–100 T capacity each) lift the transformer off the trailer deck in stages; steel sleeper stacks are built up under it; the trailer pulls out; and the transformer is lowered in controlled steps onto skid rails. Every jacking step is small — a few centimetres at a time, always supported on packing — so the load is never dependent on hydraulics alone.
Dragging: moving tonnes across a substation
From the unloading bay, the transformer is dragged to its plinth on steel rails using winches and pulley systems, over rollers or skid plates. Rates in the industry are quoted per metre of drag for good reason — distance is the job. Our crews have dragged reactor units 1,589 metres at a NEEPCO hydro project in Arunachal Pradesh, and routinely handle 100–300 m drags at substations across Jharkhand, Bihar and West Bengal.
Rotation and plinth placement
Transformers usually arrive facing the wrong way. A 90-degree rotation on rails, followed by centimetre-level positioning over the plinth and foundation bolts, completes the job. The unit is landed on its plinth in the same staged jacking process, in reverse.
- Typical crew: 8–16 riggers plus supervisor, depending on tonnage
- Core equipment: 50–100 T hydraulic jacks, steel rails and sleepers, machine rollers, winches, chain pulley blocks
- Timeline: 1–3 days per transformer for unloading + placement; dragging adds time by distance
From the field
Before mobilizing a transformer handling crew, confirm who supplies rails and sleepers, whether the drag path is compacted and clear, and whether the plinth is cured and level. These three items cause most of the delays — and delay charges.
IPN LIFTERS has been a transformer handling partner to L&T Power Transmission & Distribution since 2019 (vendor code S0157291), with work including 210 MVA at NTPC Farakka, 510 MVA at Satgachia, and dozens of 50–65 MVA units across JUSNL substation packages in Jharkhand.
Frequently Asked Questions
How is a transformer unloaded without a crane?
By staged hydraulic jacking: the transformer is lifted off the trailer a few centimetres at a time on 50–100 tonne jacks, supported on steel sleeper stacks, the trailer is removed, and the unit is lowered onto skid rails. It is the standard method at substation sites where crane access or capacity is impractical.
What does transformer dragging cost?
Dragging is priced per metre and varies with tonnage, path condition and whether rails are supplied by the contractor or client. Unloading and placement are priced per unit. Ask for a rate that separates these components so you can compare quotes fairly.
How many days does transformer unloading take?
For a 50 MVA class unit with a prepared site: typically 1–2 days for unloading, and another 1–2 days for dragging and plinth placement depending on distance. Larger grid transformers take proportionally longer.
Planning this kind of job?
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