Serbia: Overhaul season in “Drinsko-Limske HPPs“, Rehabilitation reduced costs

21. July 2014. / News Serbia Energy

Overhaul costs of the power units H3 and H4 in HPP “Bajina Bašta” are significantly lower, because most of them are covered by “Andritz hydro“. This year’s overhauls will be performed under our own steam, with the help of local companies and by hiring specialized institutes.

After a four-year rehabilitation of the power units of HPP “Bajina Bašta,” this production capacity of “Electric Power Industry of Serbia” enters into the period of regular overhaul. A smaller scope of work is evident and investment in new parts is not required. This automatically means that the maintenance costs are reduced.

-Costs of overhaul of the power units H3 and H4 are significantly lower, because most of them are covered by “Andritz hydro“. It includes a removal of small defects, so we hope that in the next period one of rehabilitation goals (reduction of overhaul costs) will be achieved. Therefore, rehabilitation and modernization of the hydro power plant is being done- points out Mijodrag Čitaković, Director of “Drinsko-Limske Hydro Power Plants”.

Regardless of the fact that the larger part of the equipment is new, in HPP “Bajina Bašta”, the usual overhaul of power units and related equipment will be performed. Overhaul first started on the power unit H3. Within this year’s regular overhaul the inspection of turbine equipment, spirals and siphons, cooling system, generators, impellers, transformers, servo motors, regulatory system and transport equipment will be performed. Currently, works on recovery of leakage between blade spindles of the connecting apparatus and lever. In these places, where leakage was noticed, gaskets will be placed.

– It will be done as a prevention on all 20 blades of the connecting apparatus on the power unit H3- says Čitaković.- During this work all the lacks noticed so far in the operation of the power unit will be removed. This will contribute the quality of installed equipment to be at the highest possible level.

According to the director of Drimsko-Limske HPPs“ operations related to the sealing are done by “Andritz Hydro” with its capacities, regardless the fact that the warranty has expired, because this lack was noticed during the warranty period. The same work will be done during the overhaul of the power unit H4, which is still under its warranty period.

According to our interlocutor, after that, the overhaul of the impeller will be done i.e. measurment of the labyrinths when the power unit stops, visual inspection of the impeller, a detailed inspection of the flow line equipment, inspection of the impeller, recovery of cavitation damage on the impeller, control of the anti-corrosive spiral and control of screws on the impeller and on the pontoon. Standard overhaul of the cooling system equipment will be performed, as well as inspection, test and cleaning of filters. Removal of the cover metal sheets on the generator, upper and lower metal barrier sheets, their control and cleaning will be done, as well as the control of bolts and all screws and welded connections.

Within the exciting system, dismantling of slip rings and their treatement in the factory “ATB Sever“ will be done. This work was done during last year on power units H1 and H2 due to colling and reduction of particles heating and their fast consumption. On the transformer, the cooling system equipment will be inspected. Inspection of the signaling equipment will also be carried out.

– Regarding the scope of overhaul on the power unit H 4, after dismantling, the inspection of entire equipment will be performed, as the warranty period expires in August – points out Čitaković. Impeller and generator will be inspected and warranty characteristics will be checked.

Overhaul operation in the pumped storage HPP “Bajina Bašta” will be performed from July 21st to August 28th, while the overhauls in “Limske HPPs” will end in November. In HPP “Zvornik” overhaul will last until October 2nd, and in HPP “Elektromorava” overhaul of all four power units will be carried out during September when the minimum inflow is expected. All this year’s overhauls in “Drinsko-Limske HPPs” will be performed under our own steam with the help of local companies and by hiring specialized institutes.

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