Lgs Ilt - Turbine Trips

Front 1

List Turbine Trips

Back 1

High reactor vessel water level
High moisture separator level
Mechanical overspeed
Electrical overspeed
MSOP discharge pressure low
Low EHC hydraulic fluid pressure
Low condenser vacuum
High thrust bearing wear/low bearing oil pressure
Loss of both speed signals to EHC
Low EHC ETS pressure
Generator lockout
Loss of 125 VDC EHC control power
Loss of stator water cooling
Manual

Front 2

Turbine Trip
High reactor vessel water level

Back 2

Reactor vessel water level +54"

Basis –This prevents drawing excessive moisture into the
H.P. turbine, which could damage the turbine blades.

Front 3

Turbine Trip
High moisture separator level

Back 3

Level 102.5 inches from the bottom of the drain tank, after a 10 second time delay

Basis - This prevents damaging the L.P. turbine blades due to excessive moisture in the steam from the moisture separators.

Front 4

Turbine Trip
Turbine overspeed
Mechanical overspeed

Back 4

110% of rated speed, or 1980 rpm

Basis – This trip prevents the turbine from operating at a speed that may result in damage to the turbine, and could result in pieces of the turbine becoming missile hazards.

Front 5

Turbine Trip
Backup turbine overspeed
Electrical overspeed

Back 5

112% of rated speed, or 2016 rpm

Basis - This trip prevents damage to the turbine due to overspeed in the event that the normal overspeed trip does not properly function.

Front 6

Turbine Trip
MSOP discharge pressure low

Back 6

Main shaft oil pump discharge pressure low (105 psig).

Basis - If MSOP discharge pressure drops this low, there will not be sufficient oil pressure to drive the oil driven booster pump. This means that the only pumps available to provide bearing header oil would be the TGOP and the EBOP, and we do not want to rely on these motor operated pumps with the turbine at rated load.

Bypassed - This trip is only active when > 1300 rpm

Front 7

Turbine Trip
Low EHC hydraulic fluid pressure

Back 7

Low EHC hydraulic fluid pressure (1100 psig).

Basis - With EHC pump discharge pressure as low as 1100 psig, an EHC failure is indicated, and the turbine steam admission valves will soon not be able to stay open, therefore the turbine is tripped.

Front 8

Turbine Trip
Low condenser vacuum

Back 8

Low condenser vacuum (21.5 inches Hg vacuum).

Basis - Low vacuum (or high backpressure) operation can result in excessive Windage, vibration, and heating of the last stage blades of the L.P. turbines.

Front 9

Turbine Trip
High thrust bearing wear/low bearing oil pressure

Back 9

45 mils of thrust plate wear/8 psig oil pressure

Basis - remove the thrust applied to those bearings, preventing blade-to-blade or blade-to-shell contact and minimize the damage done to the turbine due to the lack of oil.

Front 10

Turbine Trip
Loss of both speed signals to EHC

Back 10

Loss of both speed signals to EHC.

Basis - To prevent possible overspeed events, the turbine trips whenever both speed inputs to EHC are inoperable. Without EHC speed and acceleration control unit the turbine would accelerate at the rate selected (180 rpm per minute) until the overspeed trip actuated at 110% of rated speed.

Front 11

Turbine Trip
Low EHC ETS pressure

Back 11

Low EHC ETS pressure (800 psig) –

Basis - this trip signal ensures the turbine trip remains sealed in until the master reset pushbutton is depressed, and ETS pressure is restored to greater than 800 psig.

Front 12

Turbine Trip
Generator lockout

Back 12

Unit protection lockout relays energized.

Basis - A generator lockout signal causes the generator output breakers to open, which completely unloads a loaded turbine. In order to prevent a power-load unbalance, or overspeed, the turbine trips for any generator lockout.

Front 13

Turbine Trip
Loss of 125 VDC EHC control power

Back 13

12)Loss of 125 VDC EHC control power. This 125 VDC power is needed for most of the electrical turbine trip signals to cause a turbine trip.
Therefore, if this power is lost, a turbine trip signal is automatically generated, as described below:

a) This trip is only active if turbine speed is less than 1300 rpm. If both 125 vdc sources are lost with turbine speed greater than 1300 rpm, then the turbine will remain on line and the following turbine trip conditions will NOT cause a turbine trip:
• Loss of Stator Coolant
• Low Shaft Oil Pump Discharge Pressure
• Thrust Bearing Wear Detector High Wear
• Low EHC Hydraulic Pressure
• Generator Lockout (386 Devices)
• Moisture Separator High Level
• High Reactor Vessel Water Level
• Low Condenser Vacuum

Front 14

Trips that are inactive with a loss of 125 VDC EHC control power when turbine speed is > 1300 rpm

Back 14

• Loss of Stator Coolant
• Low Shaft Oil Pump Discharge Pressure
• Thrust Bearing Wear Detector High Wear
• Low EHC Hydraulic Pressure
• Generator Lockout (386 Devices)
• Moisture Separator High Level
• High Reactor Vessel Water Level
• Low Condenser Vacuum

Front 15

Turbine Trip
Manual

Back 15

MCR pushbutton or front standard handle