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NLO Systems > SO- Seal Oil > Flashcards

SO- Seal Oil Flashcards

1
Q

What is the purpose of the SO system?

A

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

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2
Q

How does Main Turbine Lube Oil support SO system?

A

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

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3
Q

What powers SO pump motors?

A

NH

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4
Q

What does NK power in the SO system?

A

Emergency Seal Oil Pump (ESOP) via NKN-M46

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5
Q

When is the float operated switch in the Vacuum Tank set to alarm?

A

If tank level varies 4” above or 8” below normal

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6
Q

What happens if normal Lube Oil supply to the SO Vacuum Tank is lost?

A

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

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7
Q

Where is the SO Vacuum Tank located?

A

140’ Turbine building, northeast corner

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8
Q

How does the Vacuum Tank aid in removing gasses from the lube oil?

A

As high pressure oil form the lube oil system is sprayed into the low pressure vacuum tank 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 recirculation oil pump helps remove as much entrained air and gases as possible

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9
Q

Where is the Seal Oil Vacuum Pump located? Power source?

A

140’ Turbine Building at seal oil skid

NH

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10
Q

What is the purpose of the Seal Oil Vacuum Pump?

A

Maintains the SO Vacuum Tank at a vacuum (26-27 in Hg) to help eliminate gasses from the seal oil

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11
Q

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

A

Supplies oil for sealing and lubricating the pump, supply valve opens on pump start

vents to outside atmosphere

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12
Q

What is the purpose of the Main Seal Oil Pump? Where does the excess oil go?

A

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

Returned to the tank through relief valve PSV-11

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13
Q

Where is the Main Seal Oil Pump operated from? Power source? Type of pump? Location?

A

Control room

NH

Posi. disp.

140’ turbine building, generator seal oil skid

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14
Q

How would main generator operation be affected if we didn’t have vacuum treatment?

A

The entrained air form the oil will be released in the generator. This will gradually reduce the hydrogen purity in the casing. The tech manual states that the hydrogen purity will decrease at a rate of about 2% in eight hours

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15
Q

When does the Emergency Seal Oil Pump auto start? Where can I test the auto start of the Emergency SO pump?

A

Upon receipt of a low pressure signal of 110 psig from the main seal oil pump discharge

Locally and from control room

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16
Q

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

A

The vacuum tank becomes inoperative with the emergency oil pump in operation

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

17
Q

What is the life expectancy of the SO filters? How many are in-service at a time? How are they swapped? Location?

A

2 to 6 months

1 in service, 1 in standby

completely fill the stanby filter, then shift the three-way transfer valve

140’ turbine building

18
Q

Where is the SO skid located?

A

140’ Turbine Building

19
Q

What function do the springs in the main generator Shaft Seals perform?

A

Hold the annular sealing rings together radially and separate them axially

20
Q

Concerning the main generator SO system, what prevents the release of hydrogen with the drainage of the detraining tank?

A

A float valve, LCV-24

21
Q

What is the purpose of the auxiliary detraining section?

A

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

22
Q

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

A

8 psid

23
Q

What would be an indication of a degraded seal?

A

Comparing seal oil supply pressure to the turbine end seal and the generator end seal and if they were not equal, it would be an indication

24
Q

What is the normal discharge pressure of the SO pump?

A

120 psig

25
Q

What would be my source of flow if the Emergency and Main SO pumps were lost?

A

Main Lube Oil system would supply at reduced pressure

26
Q

What would be the adverse effect of a complete loss of seal oil?

A

Hydrogen would leak out and create a fire hazard

Main Turbine will have to be tripped

27
Q

What is the purpose of the SO recirculating pump? Power source? Location? Where is it operated from?

A

takes suction on the vacuum tank which recirculates the oil to the downward facing spray nozzles in the vacuum tank to separate gases from the oil after initial spray into the tank from LO

powered by NH

located on 140’ turbine building

control room

28
Q

Where is the emergency SO pump powered from and where is it controlled from?

A

NK

control room

29
Q

With a loss of off-site power, the non-class DC electrical system will power the Emergency Seal Oil Pump long enough for what?

A

allow operators to depressurize the main generator hydrogen

30
Q

What happens on a loss of the main SO pump?

A

ESOP will start

31
Q

Where does the emergency seal oil pump take a suction from?

A

off the main lube oil supply header (bypassing the vacuum tank and decreasing hydrogen purity)

32
Q

What happens if the main SO pump and the ESOP are both lost?

A

the main LO system will supply seal oil at a reduced pressure (hydrogen will leak passed the seals until a few pounds less than the reduced seal oil pressure)

33
Q

What happens to the SO system when the Main LO supply is lost?

A

automatically becomes a closed

loop system with the drains from both detraining sections returning to the seal oil vacuum tank.

34
Q

Regarding the SO system, what is an indicator of degraded main generator seals?

A

different seal supply pressures between the collector end and turbine end of the generator

NLO Systems (66 decks)

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