Revitalization of Aggregate H4 in PC “Drinsko-Limske Hydroelectric Power Plants”, international companies in charge of the realization with domestic subcontractors

26. February 2013. / News Serbia Energy

Thanks to experience obtained from the previous phases, the demounting of the complete aggregate equipment has been performed efficiently.

The revitalization activities of the aggregate H4 in HPP “Bajina Basta” are performing according to the dynamic plan. The demounting activities are finished, and all large parts that have to be revitalized, are transported in the factories in Germany and Austria, where the repair and revitalization activities have already started. It′s a question of shaft, turbine cover, turbine blades, head and rotor arms, actuators of the operating device.

At the beginning of February, we expect the delivery of these parts on the construction site. On the very construction site, the necessary additional activities, concerning the siphon reconstructed part and turbine duct, are in the course. For the machining, the special machine of the firm “Metalok”  from England was engaged, and installed on the spot.

Concerning that the down-grade of aggregate H4 was detected, after its demounting, what was also the case, during the demounting of the previous three aggregates, so the firm “Metalok” was engaged also this time, in order to solve the problem of reconstruction. By means of already installed special tools, the upper ring is machined on the fit of the turbine cover, the lower ring, the flange hub of the siphon, and the blades fit point of the operating device. The complete machining of these surfaces is performed in order to bring the machine in the strict vertical position, i.e. to achieve the zero value of aggregate basis. In this way, the equal loading is achieved on the support bearing and turbine cover, the vibrations of aggregate and losses are going to be smaller, and on the other side, the safety in the work will be bettr.

Before the engagement of “Metalok”, the complete corrosion protection of the spiral was done, and the preparation of the platform for the wrapping up of the stator of generator, because the stator housing was already installed.

-The revitalization of the aggregate H4 is doing well.  All that was done during the fourth phase, from the turbines up to generators, is according the dynamic plan – pointed out Mijodrag Citakovic, Director of HPP “Drinsko-Limske HPPs”. – Dismounting of the complete equipment of the aggregate H4 is performed very efficiently, thanks to experience earned in the previous phases, the reliable operation of cranes and elevators, as well as the additional dismounting tools, that were made. Yet, it is left the reconsidering of the block transformers, 112 MVA, which is currently complied in  “SGB”, Germany. According to experts from this factory, the transformers will be complied in time. The manufacturers, “Institute Mihajlo Pupin” in charge for the control equipment, and “Elnos”, Banja Luka for mounting of distribution system, are performing their works according to plan.

In the last period the workers of the associated hydroelectric power plants in the Company  “Drinsko-Limske HPP-s” are increasingly engaged for outdoor facilities and access ways to hydroelectric power plants, in order to enable constant data set ready /DSR/.

– Thanks to adequate preparing for the operation in winter conditions, everything   is going without problems, up to now. The equipment and the aggregates have been operating well in these conditions, i. e. we haven′t got any faults   to be reason for the breakdowns of main equipment and in production, although the hydrological conditions are still unfavorable – emphasizes Citakovic.

When it comes to HPP ”Zvornik”, there are finishing preparation activities for the  opening of  the second bidders′ envelope for the revitalization of this electric  Power plant. The works that include the downstream annex of the right bank are very busy. The most significant works have been performed in the previous three months.

– Although we are deeply in winter, the activities are performed on the site, according all technological methods and regulations, so we can expect the annex  to be performed according to plan – says Citakovic. – In the “Limske HPP-s”, the project documentation for the  RHPP “Bistrica” has been  preparing, as well as the documentation for the revitalization of the HPP “Bistrica” and HPP “Potpec”.

We need a new professional staff

In order to enable the further secure future for HPP-s Companies, the new professional staff is needed, because the hitherto existing are retired. According to Citakovic, it is necessary to employ the new workers, engineers, which are familiar with modern technology and trends, because the readiness of capacities depends a great dial on them.

– At any time we must be technically ready to meet the challenges, the nature and technology put in front of us – says Citakovic. The parts of HPP-s and facilities are modernizing all the time, and it is necessary to rejuvenate the stuff, as soon as possible, because to become a qualified engineer, one needs four years practice at least.

Source Serbia Energy Magazine

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