ARCHIVED REPORTS LEC APPLICATION FOR CERTIFICATION

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SECTION 2.0:PROJECT DESCRIPTION load center transformers. The high-voltage side of the unit auxiliary transformers will be connected to a tap on the isolated phase bus duct or cable connecting the generator to the respective GSU low-voltage (secondary) winding. This connection will allow the switchgear to be powered from the local grid via the GSU whenever the CTG is not running or directly from the CTG when the CTG is running. A generator circuit breaker located near the CTG and the STG will be connected to each of the generators. The circuit breaker is used to isolate and synchronize the generators,and will be located between the generators and the connections to the GSU. The 4,160-volt switchgear lineup will supply power to the fuel gas compressors, other large motor loads,the combustion turbine starting system,and to the load center transformers,rated 4,160 to 480 volts,for 480-volt power distribution. The 4.16-kV switchgear will have vacuum interrupter circuit breakers for the main incoming feeds and for power distribution. Each load center transformer will be oil-filled using less flammable oil, and will supply 480-volt,3-phase power to the plant 480-volt motor control centers (MCCs). The MCCs will provide power to the various 480-volt motor loads, and other low-voltage plant loads including 480-volt power distribution panels, and lower voltage lighting and distribution panel transformers. Power for the AC power supply (120-volt/208-volt) system will be provided by the 480-volt MCCs and 480-volt power panels.480-120/208-volt dry- type transformers will provide transformation of 480-volt power to 120/208-volt power. 2.1.7.3 1251250-Volt DC Power Supply System One common 125/250-volt DC power supply system consisting of one 100-percent-capacity battery bank,two 100-percent-capacity static battery chargers, a switchboard, and two or more distribution panels will be supplied for balance-of-plant and CTG equipment. The CTG will be provided with its own separate battery systems and redundant chargers. Under normal operating conditions,the battery chargers supply DC power to the DC loads. The battery chargers receive 480-volt,three-phase AC power from the AC power supply (480-volt) system and continuously charge the battery banks while supplying power to the DC loads. Under abnormal or emergency conditions,when power from the AC power supply (480-volt) system is unavailable,the batteries supply DC power to the DC system loads. Recharging of a discharged battery occurs whenever 480-volt power becomes available from the AC power supply (480-volt) system. The rate of charge depends on the characteristics of the battery,battery charger,and the connected DC load during charging. The anticipated maximum recharge time will be 12 hours. 2.1.7.4 Uninterruptible Power Supply System The combustion turbine and power block will also have an essential service 120-volt AC, single-phase, 60-hertz (Hz) uninterruptible power supply (UPS) to supply AC power to essential instrumentation,to critical equipment loads and to unit protection and safety systems that require uninterruptible AC power. Redundant UPS inverters will supply 120-volt AC single-phase power to the UPS panel boards that supply critical AC loads. The UPS inverters will be fed from the station 125/250-volt DC power supply system. Each UPS system will consist of one full-capacity 2-18 SAC/371322/082340003(LEC_2.0_PROJECT_DESC.DOC)