Generator Seal Oil

Question 0

How is the seal oil cooled?

Answer 0

It comes from the turbine lube oil system already cooled and conditioned.

Question 1

What is the purpose of generator seal oil?

Answer 1

Control leakage of H2 gas at the annulus between the rotor shaft and it’s bearings and the generator casing to atmosphere. It also prevents impurities from entering the H2 gas and contaminating it.

Question 2

What is the power supply to the emergency seal oil pump?

Answer 2

NK M-46

Question 3

How are some of the gases separated out of the seal oil?

Answer 3

In the vacuum tank, the oil is sprayed out and atomized by the nozzles in the vacuum tank. The recirc pump provides the flow and the vacuum pump removes the gases.

Question 4

How is a vacuum maintained on the seal oil vacuum tank?

Answer 4

By the seal oil vacuum pump.

Question 5

Where does the air go that is removed by the seal oil vacuum pump?

Answer 5

The air is vented to atmosphere and the oil that gets carried over goes to a drain.

Question 6

What is the discharge pressure of the main seal oil pump?

Answer 6

120 psig, but there is a relief on the discharge that sends some excess pressure back to the vacuum tank.

Question 7

What pressure will start the emergency seal oil pump?

Answer 7

110 psig on the main seal oil pump discharge.

Question 8

What happens to the vacuum tank with the main seal oil pump inoperable?

Answer 8

No oil is being taken out by the main seal oil pump, so the recirc pump is recirculating what’s in there and not taking any out. The level control valve will close on high level to keep from overflowing the tank.

Question 9

How does the test push button for the emergency seal oil pump work?

Answer 9

Local or the control room; pushing it opens a valve that ports oil back to the vacuum tank causing a simulated low discharge pressure condition. Releasing the push button clears the condition

Question 10

How many seal oil filters are there in operation at a time

Answer 10

One. The cartridges are changed out every 2-6 months.

Question 11

What forms the seal that keeps the H2 in the generator?

Answer 11

A seal assembly that is attached at each end of the generator has oil fed in between the rings and the shaft in both directions. The oil film keeps the H2 in.

Question 12

Where does the oil that has been subjected to the H2 in the generator go as it’s leaving the generator?

Answer 12

To the hydrogen de-training section of the unit

Question 13

What prevents the release of hydrogen with the drainage of the de-training tank?

Answer 13

LCV- 24 which is a float valve keeps the H2 in.

Question 14

Where is the hydrogen de-training tank located?

Answer 14

Underneath the belly of the generator (seen from 140’)

Question 15

Where is the aux de training section located?

Answer 15

In the overhead plant south of the generator.

Question 16

When is the seal oil system put into service?

Answer 16

Prior to admitting hydrogen into the generator and is kept in service until hydrogen is purged from the generator.

Question 17

What supplies the seal oil initially on startup?

Answer 17

It’s supplied directly from main turbine lube oil through the differential pressure regulating valve.

Question 18

What happens if the main seal oil pump and emergency seal oil pump are both lost?

Answer 18

the main lube oil system will supply seal oil at a reduced pressure. H2 pressure will drop (leak past the seals) until it stabilizes at a few pounds less than the seal oil supply pressure.
Load would need to be reduced on the generator if operation is to continue.

Question 19

What happens to the system on a loss of main turbine lube oil?

Answer 19

The seal oil system automatically becomes a closed loop system with the drains from both de-training sections being returned to the seal oil vacuum tank.