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Friday, 01 February 2019

CASCADE HPP: REPAIR WORKS

We are located at HPP-2, which is along with HPP-1, is one of the main hydropower stations of the Cascade HPP. For understanding its importance in the production activities of the Cascade of Hydroelectric Power Stations, it is enough to say that by the end of 2018, the power generation of this station amounted to almost 39% of the output of the entire department, which currently includes 9 hydropower stations. Therefore, the issue of maintaining constant operational reliability of HPP-2 depends on primarily to the technical condition of hydraulic units, which it has three.

Opening of Hydraulic Unit A-3

Opening of hydraulic unit A-3. Each hydraulic unit consists of hydro mechanical and electrical equipment, in simple terms, from a turbine and a 4.6 MW generator. In order to ensure their stable trouble-free operation, it is necessary to monitor constantly the condition of the main generating equipment, eliminate any defects in time that occur and, if possible, prevent them. And this is not easy, that HPP-2 has been in operation since 1959 and there is no staff duty on it. The station is controlled by the telemechanics of the NSC (the head of the shift of Cascade HPP) twice a day, and along with other stations operating in automatic mode, it is visited by the duty engineer. According to the results of the control, records are registered in the station log about the problems in the equipment and detected defects. Something is eliminated promptly, something can be done only for several hours with a short-term station stopping, and something requires partial or complete disassembly of the hydraulic unit according to the dispatching requests, for several days for repairs.

Repairs can be current and capital. The current ones, at which the accumulated defects are eliminated and the procedural preventive measures are carried out for replacing individual parts and servicing hydro mechanical and electrical equipment units are held once a year by economic means (in other words - on their own). And the frequency of capital repairs is regulated by the "PTE of power plants and networks" and is determined once every 5 years. Accordingly, the nature and scope of work during the overhaul is much wider and may include replacing the main units of the hydraulic unit (for example, replacing a turbine shaft) or rewinding the generator windings. Of course, such work can be only performed by a specialized contracting organization that has the appropriate equipment, repair facilities and qualified personnel.

Head of EMC Sergey Kisselev

“Today, the maintenance and operating personnel of the Cascade of Hydroelectric Power Plant is carrying out permanent work of the hydraulic unit № 3,” said Sergey Kisselev, head of the electromechanical workshop. - Now the unit is partially disassembled, the front covers of the generator and the turbine cover are removed. Electricians from the ESP group (electric power equipment), after inspecting and purging parts of the generator with compressed air, inspect and check the attachment of the poles and inter polar rotor connections, replace the worn brushes and regulate the brush holders, increase and polish the pathogen collector and measure the resistance parameters of the windings.

Locksmith EMC Khudaybergenov N.L. installs thermosignalizers generator bearings

And here, specialists from SIPA work and revise their equipment - AGP panels, ARV and UBV devices, excitation cables, etc. Engineers and mechanics from the GMO group - hydro mechanical equipment deal with the mechanisms.

Engineer TSAIS Omiraliev R.S. and electrician Carten D.J. measure the parameters of the excitation circuits of the generator

After inspecting the turbine and checking its general condition before repair, they will have to take characteristics and check the actions of the mechanisms and devices of the regulation and automatic control system, replace the cuffs and sealing gaskets, check and adjust all the gaps, eliminate all defects and damages previously detected and discovered at the opening of the hydraulic unit, and much more.

Locksmiths GMO EMC Hizhnichenko P.V. and Atutan A.S. inspect the pump MNU

And at the end of all planned and unforeseen repair activities, the hydraulic unit must be assembled, tested and, if successful, allowed to continue operation.

Detection of nodes MNU

And for all this, 9 days are allotted: according to the schedule approved by the Chief Engineer of AlES JSC, the repair of the hydraulic unit №3 of HPP-2 should be completed by February 5.

Repair of the impellers by an electric welder A. Kolesnikov

Now the work is in full swing. But at the same time, no one forgets about strict compliance with safety regulations. Works are carried out in due form, personnel are provided with protective equipment, the place of work is fenced and relevant warning posters are posted. All of this is monitored by the occupational health and safety service of the HPP Cascade.

Verification of workplaces by the senior inspector of the Security Service and Labor Department Grankina N.V.