the generator must be brought up to synchronous speed by the prime mover and then the circuit breaker switches must be closed when the generator is in phase. This generator may fall out of synchronization easily if perturbed, and hunting between generators working in parallel may be a problem. The reactive power generated can be adjusted by the de field excitation. An ac induction generator (squirrel cage type) is a third choice although it is not commonly used for generation. It is inexpensive (about one third that of a synchronous generator) and easy to start. Line power can run the machine as a motor to near synchronous speeds with a slight frequency lag. This will spin the Brayton engine, and as power is provided to the shaft, it will generate power as the speed of the machine is increased to slightly greater than the synchronous speed. It is easy to run and inexpensive to maintain. It is about 2% less efficient (on an absolute basis) than the synchronous generator, and reactive power is obtained by additional cross-the-1ine capacitors. Since the de generator is both more expensive itself and requires the additional expense and inefficiency of dc-ac inversion, an ac generator is considered more suitable for this application. Even though it is 2% less efficient, the ac induction generator is cheaper and easier to start, operate at synchronous speed in great numbers and maintain than the synchronous ac generator. (A 100 MWe power plant may require approximately 5000 generators.) It has, therefore, been selected for the present study. Underground aluminum cables are considered most suitable for power collection. Rapid burial is available via mechanized methods. Aluminum cables are generally larger in diameter than copper, and heat dissipation to the ground is easier. Aluminum is also lower in cost. The cost for the buried cable is about $10/ft of which 90% is installation and 10% is material cost. Thus, the wire size affects the cost in only a minor way and has been left out of this study. The exception
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