RHE Velebit is a reversible derivation production plant with a capacity of 276 MW in generator and 240 MW in motor mode (276 / -240 MW). It is located in the lower reaches of the Zrmanja river, about 10 km upstream from the town of Obrovac.

The construction of RHE Velebit started in 1978. It was commissioned in 1984 and was then one of the largest reversible hydroelectric power plants in Europe. The construction of a well-type engine room, deep in the rock, was particularly demanding. RHE Velebit is among the most complex hydropower facilities in Croatia. In addition to the production of electricity, the significance of RHE Velebit is the possibility of pumping mode of operation, i.e. “storage” (accumulation) of excess electricity produced from conventional fossil fuel power plants, run-of-river hydropower plants, energy produced from wind power plants and other renewable sources.

RHE Velebit engine room is an electric power plant that was built at a depth from 11.00 m above sea level to -54.00 m and at a height from 11.00 m to 22.40 m and consists of 10 levels (floors) which form functional units. In the evacuation staircase of the RHE Velebit engine room, which includes all floors and is the only evacuation staircase in the RHE Velebit building, no smoke and heat drainage system or overpressure protection system (so-called pressure differential system, PDS) is installed.

In collaboration between HEP Proizvodnja d.o.o. and CTP PROJEKT, a conceptual solution of overpressure ventilation of the evacuation staircase whose total height is 63 m was created, which makes this staircase the highest among energy facilities in Croatia.