At Leningrad NPP, the tests of generator transformers and auxiliary transformers of the VVER-1200 power unit under construction are completed. They are ready to provide facilities with energy required for the hot trial stage. The 72-hour testing confirmed that this electrical equipment was assembled in a high quality and will function in accordance with the project throughout the Plant’s life.

Andrey Morozov, the Head of the Electrical Shop of Leningrad NPP under construction, “Electrical equipment tests were conducted at idle. Current conductors – SF6-insulated and overhead, as well as transformers received the operating voltage. Within three days specialists monitored their work. The carried out tests were considered successful: electric equipment withstand the stress. No remarks, no refusals, no defects were occured.”

As Alexandr Rudnik, the Deputy Chief Engineer for CPCS of Leningrad NPP under construction, explained, the power supply to transformers and current conductors was performed during the commissioning works within the third stage of the technical conditions for connection of the power unit No 1 to the electric networks. “The whole range of works envisaged at this stage will be completed in the very near future: the specialists will check the circuits for switching on the automatic transfers, and then change the power scheme of all 10 kV sections to a regular one. Thus, the auxiliaries of the unit being built will be provided in full capacity.”

The Chief Engineer of Leningrad NPP under construction Alexandr Belyaev noted the importance of the auxiliary voltage, “Auxiliary voltage supplying through block and auxiliary transformers is a prerequisite for performing a full-scale commissioning at the VVER-1200 power unit under construction. Having fed the equipment according to this regular scheme, we green-lighting the stage of hot trials that check the working capacity of the reactor unit under design conditions – at the operating pressure and temperature parameters of the primary circuit.”

The block transformers and auxiliary transformers are very important equipment for the power unit. They serve to lower the high voltage of the supply network to the established level of consumption (in this case from 330 kV to 10 kV). Low voltage is applied to equipment and machinery; and there are thousands of them at each power unit. Among them there are especially responsible consumers with very strict requirements to the reliability of the power supply.

Sergei Smirnov, the Deputy Head of the Electrical Shop of Leningrad NPP under construction, “According to the security conditions, power interruptions can be for no longer than few seconds. In case of the block transformers’ failure, reserve transformers are provided. And if they are not able to perform their functions, diesel generator sets will join. Such a three-fold backup of power supplies is provided by the project.”

The Leningrad NPP is an affiliate company for Rosenergoatom Concern OJSC. The plant is based in the city of Sosnovy Bor, 40 km to the west from Saint Petersburg at the Gulf of Finland shore. The Leningrad NPP is the first Russian nuclear power plant having RBMK-1000 reactors (uranium-graphite channel-type thermal neutron reactors). The NPP exploits 4 power blocks with the electric capacity of 1000 megawatt each. Also, pursuant to the NPP-2006 project, 1,2 VVER-1200 power blocks included into The State Atomic Energy Corporation ROSATOM long-term plan are being constructed. Rosenergoatom Concern OJSC is the owner and developer of the project. Holding TITAN-2 is the primary contractor. ATOMPROEKT is the general designer.