Generator Seal Oil

Question 1

What is the purpose of the SO system?

Answer 1

To control leakage of generator hydrogen gas at the annulus between the rotor shaft, its bearings and the generator casing to atmosphere.

Maintains hydrogen purity by preventing atmospheric contamination of the hydrogen gas

Question 2

How does main turbine lube oil support SO system?

Answer 2

Provides cooling and conditioning seal oil and provides backlup to the seal oil system supply

Question 3

What powers the SO pump motors?

Answer 3

NH

Question 4

What does NK power in the SO system?

Answer 4

ESOP

Question 5

when is the float operated switch in the vacuum tank set to alarm?

Answer 5

If the tank varies 4” above and 8” below normal

Question 6

What happens if normal lube oil supply to the vacuum tank is lost?

Answer 6

Seal oil is automatically recirculated and returned to the vacuum tank via the seal drain

Question 7

How does the vacuum tank aid in removing gasses from the lube oil?

Answer 7

High pressure oil is sprayed into the low pressure vacuum tank and the surface area of the oil increases allowing the gasses to come out of solution.

this process is aided by the low pressure in the tank.

the added spray flow from the recirc oil pump helps remove as much entrained air and gases as possible

Question 8

What is the purpose of the seal oil vacuum pump?

Answer 8

maintain the SO vacuum tank at a 26-27 HG to help eliminate gasses from the seal oil

Question 9

What is the purpose of the separator tank mounted above the pump?

Answer 9

supplies oil for sealing and lubricating the pump

Question 10

What is the purpose of the main seal oil pump?

Answer 10

Takes suction on the vacuum tank and pumps oil to the shaft seals 83 psig

Question 11

where does the excess oil go?

Answer 11

Returned to the tank through relief valve PSV-11

Question 12

Where is the main seal oil pump operated from?

Answer 12

control room

Question 13

how would generator operation be affected if we didnt have vacuum treatment?

Answer 13

Hydrogen purity would decrease about 2% every 8 hours

Question 14

When does the ESOP auto start?

Answer 14

LP signal of 110psig from the main seal oil pump discharge

Question 15

How is the vacuum tank affected by the emergency SO pump running?

Answer 15

Vacuum tank becomes inop with ESOP operation

Since the pump is taking suction from the oil supply header, this allows the vacuum tank to fill the oil, thus causing level control valve LCV-25 to close so that no oil enters the tank

Question 16

Where can i test the auto start of the ESOP?

Answer 16

Locally and from the control room

Question 17

What is the life expectancy of the SO filters?

Answer 17

2-6 months

Question 18

What function does the spring in the shaft seals perform?

Answer 18

Hold the rings together radially and separate them axially

Question 19

What prevents the release of hydrogen with the drainage of the detraining tank?

Answer 19

The LCV-24 float valve

Question 20

What is the purpos of the auxiliary detraining section?

Answer 20

Provides a large surface area which removes air from the oil leaving the outboard section of the seals and the generator bearings before it returns to the common bearing oil drain

Question 21

What DP is maintained between the SO supply pressure at the seals and the hydrogen pressure in the generator casing?

Answer 21

8 psid

Question 22

what would be an indication of a degraded seal?

Answer 22

Comparing seal oil supply pressure to the turbine end seal and the generator end seal and if they were not equal

Question 23

What is the normal discharge pressure of the SO pump?

Answer 23

120psig

Question 24

What would be my source of flow if the ESOP and main SO pumps were lost?

Answer 24

1) main lube oil system would supply at a reduced rate

Question 25

What would be the adverse effect of a complete loss of SO?

Answer 25

Hydrogen would leak out and create a fire hazard and main turbine would have to be tripped