PS HPP Čapljina is a pumped-storage reversible HPP, located on the lower course of the Trebišnjica River in the Herzegovina. Construction thereof commenced in late 1972 and it was commissioned in 1979. A 636-meter-long tunnel leading through the mountain massif allows access to the underground engine room with a size of 24 × 98 × 77 m, which makes it one of the largest structures of its kind in the world.

Two three-phase synchronous motor-generators are installed in the underground engine room. Each of them has a rated power of 240 MVA, Francis-type reversible turbines, and an installed power of 250 MW. The installed flow per unit is 112.5 m³/sec. Motor-generators and turbines are located in two pits inside the engine room, the depth of which is 50 meters below sea level due to the operating conditions of reversible motor-generator sets in the pumping plant.

Main scope of work includes refurbishment of stator winding by repair/replacement of stator winding bars and delivery of spare stator winding bars, replacement of stator wedges, re-insulation of the rotor winding, as well as overhaul works, inspections and modifications performed on other parts of motor-generator equipment (generator bearings, coolers, etc.). The motor-generator rotor is the heaviest piece of equipment installed in the pumped-storage HPP. It weighs 280 tons and is transferred by two crane bridges that are operated synchronously during the removal and repositioning of the rotor. These two activities represent one of the most demanding and sensitive tasks.

KONČAR – Generators and Motors Inc. is also involved in the execution and the supply of specified equipment. Project completion is scheduled for December 2021.