Sumatron has completed electrical design reviews for the following facilities:

(1) Large refinery

(5) Peaking unit stations

(7) Combustion turbine generating stations

(13) Oil/gas fired steam generation stations

(8) Coal fired steam generation stations

(1) Nuclear generating station (protecton only)

The largest station completed was 2,800 megawatts. Most of the facilities were older than 10 years, but a few were under 2 years. Since all reviews disclosed problems that could easily be resolved and result in significant cost savings, the customers considered them more than worthwhile. Typically findings were:

• Protective relays not coordinated properly.
  
  
• Protective relays set outside the withstand capability of the apparatus being protected.
  
  
• Lack of industry standard protection functions.
  
  
• Lack of industry standard alarm functions.
  
  
• Important measurements not included in DCS system.
  
  
• Improper lockout circuits.
  
  
• Non-standard or unnecessary tripping functions.
  
  
• Incorrect nomenclature or labeling of protection functions.
  
  
• Transformer taps not optimized; bus voltage too low.
  
  
• Bus transfer schemes stress motors during transfer operations.
  
  
• Ground detection schemes not mitigating high transient voltages.
  
  
• Unnecessarily high ground fault current levels.
  
  
• Medium voltage cable shielding not mitigating motor switching transients.
  
  
• Poor electrical operating procedures and practices.
  
  
• Facility electrical energy conservation and demand reduction practices poor.

The electrical design reviews for multiple unit generating stations can normally be completed in 60 hours of on-site work and includes a written report and presentation to plant management. It works best to have someone from your company participate in the review; preferably, an electrical engineer that is responsible for the station or group of stations, or a protective relay technician. This participation has three advantages, it provides training or mentoring for the participant, reduces the time spent in locating drawings and documents related to the review, and finally the participation facilitates plant buy-in of the recommendations presented in the report. 

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