Turbine/ Generator Flashcards
(47 cards)
- What are the eccentricity requirements before rolling the turbine?
Less than 3 mills
- What oil pumps should be in service before rolling the turbine?
SOB, BOP, EH pump, Air side seal oil pump, Hydrogen side oil pump, bearing lift pumps on H3.
- What sources supply Auto stop oil?
SOB below rated speed
Main shaft at 2/3 rated speed
- What are the minimum degrees superheat that you can have to roll the turbine?
100 degrees superheat
- What steam conditions are required for a cold start?
Must have 100 deg superheat, total steam temp less than 800 deg to limit stress applied during rotor heating
- What temperatures determine a cold start? Hot start?
Cold start: either the first stage metal temp or the IP blade ring temp is below 250 deg F
Hot start: both the first stage metal temp and the IP blade ring temp is above 250 deg F
- Name the turbine-generator trip relays? Where are they located?
Reverse power
2) Generator backup
3) Generator differential
4) Generator ground
5) Loss of excitation
6) Overexcitation
7) Negative sequence
8) Main power transformer differential
9) 6900 NS transformer fault pressure
10) 6900 NS transformer differential
11) 6900 NS ground
12) 4160 NS transformer fault pressure
13) 4160 NS transformer differential
14) 4160 NS transformer ground
15) Substation trip FK05
16) Under frequency
Located in the relay rooms for each unit, can also be seen on generator master page
- What are the transfer speeds for Unit #1 #2 and Unit #3?
H1 and H2 – 3425 RPM
H3 – 3500 RPM
- What temperature requirements have to be met before transferring from Throttle valve control to Governor valve control? Why?
Deep well temperatures left and right must be greater than or equal to saturation temperature at existing throttle pressure. This is to prevent water induction.
- What are the rotor stress limits?
+/- 75 degrees F
- What conditions require a Turbine heat soak?
If either first stage metal temp or IP blade ring temp is below 250 deg
- What is the purpose of a Rotor Warming Hold period during a cold start?
To evenly warm the rotor to a point where the first stage metal temp and the IP blade ring temp is above 250 deg F
- What is heat soak speed on Unit #1 ,#2 and Unit #3?
H1 and H2- 2170
H3- 2175
- Explain how to put the steam seals in service. When would you put them in service and what steam pressure and temperature do you need to put them in service?
Select “turbine aux.” page, start the gland steam condenser exhauster.
Open the HP and LP steam seal supply valves, use the HP steam seal bypass if necessary, to help achieve 3 psig.
Ensure 250 – 350 lbs throttle pressure and 25 degrees superheat before putting steam seals into service.
- Explain the following: Field breaker, , Voltage regulator test and on position and voltage adjuster.
Field Breaker - connects the PMG to the voltage regulator.
Voltage regulator test - in the “test” position the voltage adjuster is used to zero buck and boost for a bump less transfer.
Voltage regulator on – in the “on” position is used to control machine voltage. Voltage adjuster – with the voltage regulator in the “on” position, the voltage adjuster is used to adjust system voltage.
- Explain the following: MEL, KFL, OXP and MXL.
MEL-minimum excitation limiter-clamps voltage regulator which keeps voltage from going lower than a predetermined KVA
KFL-loss of field relay-trips the unit on loss of excitation maintained by system operations department, looks at generator output and trips unit above the steady state stability curve
OXP-over excitation protection- if excitation continues to increase, at 110% of rated rotor current OXP protective relay begins timing and will time out in 23 seconds at 110% rated generator current and trips the voltage regulator to base adjuster control, if excitation has not returned to normal level in 3 seconds after it times out it will trip the generator
MXL-maximum excitation limiter-prevents generator from overexciting by clamping the voltage regulator, it comes in before the OXP
- Explain the operation of the auto synchronizer.
The auto synchronizer will engage at 3602rpm, once engaged the voltage will auto adjust to match the incoming and running voltages. When the scope reaches midnight it will close in the generator breaker and the unit will be online. The generator breaker will then need to be red flagged
- What is the purpose of the synchroscope?
It allows operator to see when generator frequency is matched to system frequency
- When looking at the synchroscope, what does incoming and running mean?
Incoming – is the voltage the generator is putting out
Running – is the voltage from the system
- What is the reason for matching voltages when synchronizing the Generator breaker?
To ensure a bump less transfer, ensure all 3 phases are in sync, and, prevent excessive VAR flow
- What effect does generator speed have on the synchroscope?
The generator speed affects frequency. If generator frequency is higher than the system, then the synchroscope rotates clockwise.
If generator frequency is lower than the system, the synchroscope rotates counter-clockwise. The bigger the gap in frequencies the faster the synchroscope turns.
- What is the reason for a syncro accepter?
Ensures that generator freq & system freq are matched so that you do not sync out of phase
- Explain the operation of putting the generator on line after recalling 3602.
Notify marketers that we will be coming online shortly
- Generator Master Page Close in field breaker and ensure you see a “NAC”
- Close in VR control switch
- Observe generator voltage increases to approximately 24KV (do not let voltage exceed 25KV. Open field breaker if voltage increases past 25KV)
- Increase voltage with the voltage adjuster to 24KV if needed
- Place voltage regulator mode control switch to “auto” once the “Ready to
- Transfer” light is backlight
- Unlock generator breaker
- Place the synchro scope for the generator breaker in the “auto” position
The controller will RAISE or LOWER the exciter voltage to bring the Generator voltage to that of the system (The Generator voltage must be within +/- 0.5% of the system voltage in order for the auto synchronization relay to operate. It will also increase or decrease the speed for frequency matching) - The Generator breaker should close automatically if the above conditions are met.
- Red flag the Generator Breaker control switch
- Generator will now be online
- Verify a minimum of 5-10mw
- When the Generator breaker closes, the Turbine Master will automatically reject to manual to align its output to coincide with valve position rather than turbine speed
- Adjust and maintain the unit VARS at zero with the voltage regulator until the unit is at approximately 150 MW
- After coming online, what is the best way to control rotor stress?
Monitoring steam pressure and temperature, ensure rotor stress does not exceed +75° or -75° by opening and closing governor valves
