Main Generator and Auxiliaries

Question 1

The Main Generator and its supports systems are the main link between the nuclear reactor and the high voltage transmission lines.
Volts? Hetz? RPM?

Answer 1

-Produces 22,000 Volts at 60 Hertz
-1800Rpm
-Power is delivered to the 230KV transmission system
-Most of our in-plant loads are normally off the 22kv systems via the Unit Aux Transformer
(Supplies the 4kV Buses 2 and 4)

Question 2

Major Components of the Main Generator?

Answer 2

• Generator itself
• Generator Gas System (Hydrogen)
• H2 Seal Oil System
• Excitation System (Exciter) (Voltage Regulator)

Question 3

Flow of energy

Answer 3

• Nuclear Energy (Reactor)
• Thermal Energy (Reactor and S/Gs)
• Mechanical Energy (Turbine)
• Electrical Energy (Main Generator)

Question 4

Main Generator purpose?

Answer 4

-Converts energy from the reactor to electricity

Question 5

Hydrogen system pupose?

Answer 5

-Cools the main generator

Question 6

Seal Oil System purpose?

Answer 6

• Provides oil to seal the rotor ends of the main generator, preventing H2 leakage.

Question 7

Excitation system purpose?

Control Power supply?

Answer 7

• Excites the main generator AC field on the rotor

- 125VDC station battery (DP-A)

Question 8

Generator is cooled by Hydrogen, why? where does the heat absorbed by the H go?

Answer 8

• Hydrogen is unutilized because of its heat transfer ability and low molecular weight, which results in lower windage losses. (friction)
• Heat is transferred to Service Water by 4 heat exchangers located within the generator casing.

Question 9

What does the Generator Gas system do?

Answer 9

• Provides a means for putting H2 in or taking H2 out of the generator using CO2 as a scavenging medium.
• Maintains the gas pressure in the generator at 71-75psig.

Question 10

Seal oil pumps power supplies?

Answer 10

• Air side- MCC-4
• Air side backup MCC-C
• Hydrogen side MCC-3
• Seal Oil Backup pump MCC-20 (Lube oil reservoir)

Question 11

FCV-4421

Pressure regulator valve

Answer 11

• Maintains Air side seal oil ~12psi above H2 pressure.(MIN 3psi)
• H2 is normally at about 71-75psi

Question 12

FCV-4420

Backup reagulator valve

Answer 12

• Auto opens when air side pressure drops to 8psi above hydrogen pressure.
• Allows oil from either the main turbine shaft oil pump, or the Seal oil backup pump(AC)(Top of lube oil reservoir)

Question 13

Air side backup pump (DC) turns on when?

Answer 13

-Oil pressure at the seal drops to 5psi above hydrogen pressure.

Question 14

Seal oil back up pump auto starts when?

Answer 14

-8psig bearing oil pressure, supplies with turning gear pump

Question 15

FCV-4423 and 4422

Pressure equalizing valve (Hydrogen side)

Answer 15

-Maintains the H2 side seal oil pressure equal to the pressure of the air side seal oil pressure. (Both on the seal oil skid)

Question 16

Defoaming tanks, what do they do? and location?

Answer 16

• Defoaming tanks is what the Hydrogen side seal oil drains to before returning to the seal oil skid.
• They help remove hydrogen entrapped in the oil.
• located on the bottom side of the generator on both ends.

Question 17

H2 side seal oil tank

Location, too high, too low

Answer 17

• Located on seal oil skid
• Too high a level, float valve opens and oil is drained to suction of air side pump
• Too low, a float valve opens and oil is delivered to tank from discharge of air side pump

Question 18

Seal oil temperature should be maintained between what temperatures? Also the air side and hydrogen side oil tempts should be maintained within?

Answer 18

• 100-120F

- Within 2F of each other

Question 19

Important pressures for seal oil skid:

12psig, 8psig, 5psig

Answer 19

• 12psig- The pressure maintained above H2 pressure by the air side oil pump (or DC backup pump) (Normal)
• 8psig- Seal oil pressure maintained above H2 pressure by Turbine Lube Oil system
• 5psig- Auto Start of the DC air seal oil backup pump