Main Generator Stator Replacement

In association with company Siemens we prepared project documentation for the ''Replacement of Main Generator Stator'' which was replaced during the outage 2010. The main Generator of NPP Krško is 4-pole cylindrical-Rotor synchronous Generator, which was originally manufactured by Westinghouse Electric Corporation in 1977 and has been in continuous operation in base load regime from 1982.

Due to the wear of Thermalastic® insulation of Stator winding, design life of Generator and life extension anticipated NEK has decided to replace the old Stator. The new Generator Stator has been designed and manufactured per the NEK requirements by Siemens AG (Picture 1).


Picture 1: New Stator of the Main Generator (outage 2010) 

Scope of the project has also included modifications on existing Generator and other supporting systems. Design analyses, calculations and procedures have been performed to ensure that new installed Stator of the Generator will be equivalent replacement for the old one. Few of the analysis and calculations that were performed:

  • Power Supply Cables Sizing 
  • Transport Route Analysis 
  • Turbine Building Foundation and Load Capacity Analysis 
  • Cable Tray and Conduit Supports Calculation 
  • Analysis of Explosion Protection 
  • GN Piping Supports Calculation 
  • Analysis of Additional Load on TC System 
  • Measurement and Control List 

Sipro responsibility was also examination of the analysis and calculations which were provided by the costumer:

  • Final procedure for the exchange of the Generator 
  • Calculation of Generator Parameters, Characteristics, Design 
  • Study for Isolated Phase Bus Duct 
  • Generator Mechanical Stress Evaluation 
  • Design Approach Report to Fulfill 40 Years Service Life 
  • Torsion Study 
  • Transformer Study 
  • Study of the Protection Setting for the Generator and Other Systems 
  • Protection Terminals Settings Calculation 

Based on results and conclusions of the analysis, studies and calculations Sipro has produced complete project documentation per NEK procedures.

Project Manager: Andrej Avšič, B.Sc.E.E.