(16MW) are in parallel and connected to a circuit breaker (C-|). This is a metal clad, bifurcated (2 x 4) type capable of interrupting 1000 MW at 1200 A. The cost is only 2.56$/kWe. The high voltage transformer (Til) has a double primary and steps up the voltage from 25 kW to 230 kW. It is an oil filled, outdoor type, has a 99% efficiency and costs 2.68$/kWe. Several other circuit breakers with capacitors are used at a cost of about l$/kWe. Power factor correction as indicated in Section 2.1.3 is provided by using capacitor banks connected through circuit breakers at a cost of 1.80$/kWe (not shown in Figure 13). In addition, there are cables of 480 V and 25 kV to collect the electric power and bring it to the high voltage transformer. The cost of this cabling is estimated at 10$/kWe for the 480 V lines and 10.70$/kWe for the 25 kV lines. Adding miscellaneous costs of 10.8$/kWe, the total cost is 49.5$/kWe. The generator and motor starter cost of about 70$/kWe is excluded here since it is in the earlier estimates of the Brayton engine. The collection efficiency is made up of the two transformers and cabling losses. The cable efficiency is estimated at 95.8% and is directly coupled to the capital cost. Thus,the overall electrical collection efficiency is 93.4%. When some of the components are oversized by 20% to match the Brayton engine peaking capacity, the capital cost is estimated to be 55$/kWe for a total collection of 1000 MWe (Table 9). This total would be somewhat less if the plant was rated at only 100 MWe. In summary, all the building blocks of the electrical part of the power plant are commercially available. Induction type ac generator and underground aluminum cabling offer the most advantages. Additional study is needed to equalize the voltage drops in all parallel branches and to devise methods to automate the system for startup, shutdown, etc.
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