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System Design. The load tripping scheme Isolates portions of the system and 

 rotates the outages among areas to ensure equal exposure by all customers. 



Table A-3 shows the methodology for determining the value of 

 stability reserves. The total Investment cost for Installing a system-wide 

 load tripping scheme Is $3.8 million (Table A-3, line 9, column C). The 

 annual Investment cost, $0,729 million (Table A-3, line 11, column C), Is 

 based on a 14 percent Interest rate and a 10-year life. A 10-year life was 

 chosen to annualize the total Investment because the need for a load tripping 

 scheme will substantially change after 10 years due to technological change. 

 Annual maintenance costs are $0,047 million per year (Table A-3, line 16, 

 column C). Thus, the total annual cost associated with Installation of an 

 alternative load tripping scheme is $0,776 million (Table A-3. line 17, 

 column C) . 



C. Plant Delay Reserves 



For valuing plant delay reserves. BPA assumed the combined cycle 

 combustion turbine would be operated to meet outages. The costs associated 

 with running the turbine Include fuel and variable operation and maintenance 

 costs. These costs were escalated to reflect the costs in the year In which 

 the restriction is expected to occur. In Table A-4 these costs (Columns C 

 and E) are multiplied by the expected megawatts (Column B), then summed to 

 calculate a total running cost (Column G). These total costs are discounted 

 and summed to derive the total value of plant delay reserves over the 7-year 



A- 11 



