Replacement of uninterruptible power supply units in Unit 2 of INPP


To ensure reliable shutdown and cooling of the reactor in the event of power failure at all external sources and to ensure power supply to the protection systems and computer information system in normal and emergency conditions at Ignalina Nuclear Power Plant, 6 uninterrupted power supply systems were installed consisting of storage batteries (AB), DC panels (SHPT) and ABP equipment with power current rectifiers for charging storage batteries, converters that convert direct current of the SHPT to alternating current, and thyristor switch-off devices, ensuring uninterrupted power supply to critical consumers of the protection system.

The main objectives of the project were as follows: replacement of morally and physically obsolete ABP-1500 equipment, which had been manufactured at industrial plant INVERTOR (Orenburg, Russia); improvement of reliability of the protection system and improvement of its service conditions by reducing troubleshooting time; and, improvement of operational reliability of the INPP equipment in cases of seismic events and other extreme conditions.


  • Designing, manufacturing, testing, and delivery of a new certified unit for step-by-step replacement of the following equipment: 8 power rectifiers TPPS-800, 21 converters PTS-200 and 18 thyristor switches for the interruptible power supply units ABP-1500 of Unit 2 of Ignalina Nuclear Power Plant. Preparation of the project for the replacement of uninterruptible power supply units ABP-1500 and its submission together with drawings, calculations, technical specifications, and supporting documentation. Commissioning, testing, and putting into operation of the delivered and installed equipment. Training of repair and maintenance personnel validated by the manufacturer’s certificate.
  • Since the technical characteristics and design of the newly installed Swiss equipment GUTOR was different from the technical characteristics and design of the previous uninterruptible power supply system, comprehensive solutions and calculation methodologies were prepared in order to define the structure and parameters (including the parameters of units and equipment and the selection of protection systems, cable cross-sections, etc.) for all the components of INPP Power Unit SPB, taking into consideration the characteristics of the new equipment and minimum costs of the reconstruction of the existing auxiliary system.
  • In addition to the new rectifiers and converters, thyristor switches were installed as protection devices in distribution panels after converters. This equipment was specifically designed for use in auxiliary power unit of INPP Unit, upgraded within ABP, and is intended for quick disconnection of single and three-phase uninterruptible power supply consumers on individual or shared power lines.
  • A training and skill development centre for INPP staff was set up, where rectifiers, inverters, and disconnection equipment of similar design, features and performance characteristics as in “large” ABP plants are used.

The main technical solutions for SBP reconstruction (including structural diagrams, selection of parameters based on the calculations, as well as preparation of the technical design) were carried out by our subcontractors OOO PROELEKTRO (Kiev, Ukraine).

Equipment commissioning, testing, and handover to operation were carried out by our subcontractors OOO SELKOM (Kiev, Ukraine).

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