MAIN POWER DISTRIBUTION

Question 1

List two major functions of the Main Power Distribution System.

Answer 1

Distributes electrical power to plant components for plant operation through the system network of buses, transformers, switches, breakers & related equipment.
System receives power from the switchyard, main generator, or the emergency diesel generators.

Question 2

State the operating voltages for the following transformers:

Answer 2

a. Main Transformer
Step up voltage from 22 kV to grid voltage, 230 kV
b. Auxiliary Transformer
2 auxiliary transformers per unit step down the voltage from 22 kV through 2 sets of windings per transformer.
1 set of windings powers its respective A1 or B1 6.9 kV bus.
The other set of windings power its respective A2 or B2 4.16 kV buses.
c. Startup Transformer
Step-down 230 kV voltage from switchyard for use on the unit 6.9 kV buses & the 4.16 kV station cross-tie buses, 2A4 & 2B4.

Question 3

List the three loads on each 6.9 kV bus.

Answer 3

Each 6.9 KV bus supplies only 2 RCPs & 1 Main FW Pump.