Transformers moved in deep cave by Mammoet

A hydro-electric power station in Kafue Gorge, Zambia, required the transportation and installation of six transformers down a 1.2 kilometre deep cave. International heavy lift and transport company Mammoet completed the job, ensuring an on time delivery that helped the power station to keep running while the old transformers were replaced and moved out one after the other.

The power plant, run by the Zambian state-owned Zesco electricity company, supplies around 40 percent of Zambia’s power capacity - an essential facility to help meet Zambia’s increasing power demand, the company said.

Mammoet had already transported and installed the first four out of a total of ten new transformers back in 2012. In 2015 the company also won the next contract to transport and install the following six new transformers. In total, Mammoet transported and installed ten new transformers and moved ten old transformers out of the powerhouse inside the cave.

The transformers were collected from the manufacturing facility of Royal Smit Transformers in Nijmegen, Netherlands, and transported on a barge to the port of Antwerp in Belgium. The transformers were then handled from river vessel onto an ocean vessel and taken by sea over 9,000 km to Walvis Bay in Namibia. The transformers were then transported on conventional trailers using two prime movers over 2,200 km to Kafue Gorge.

Each new transformer, weighing 105 tonnes, had to be driven down a 1.2 km long tunnel inside a cave to the installation area. This road is on a gradient with just a few centimetres clearance above the transformers in some places. Mammoet reconfigured the trailers to fit the confined space and used two trucks – one at the front to pull and one at the back to push – with Mammoet team members working in close co-ordination to safely and securely negotiate the steep slope.

Every two weeks, Royal Smit Transformers did the work to disconnect the old and reconnect the new transformers one at a time, while Mammoet moved them in and out of the powerhouse. The old transformers were loaded and the new transformers offloaded using an overhead gantry crane. Since working height was very limited inside of the cave, Mammoet designed and fabricated a tailor-made lifting frame - in collaboration with Royal Smit Transformers - to manoeuvre the transformers into place.

After each new transformer had been running for 24 hours without incident, preparations were started to disconnect and replace the next transformer.