345KV Switchyard Flashcards
What is the purpose of the Palisades 345KV Switchyard?
Connects Palisades to the power system.
Provides 2 physically independent sources of offsite power.
Function reliably under all modes of plant operation.
Isolates faults in the system under normal and abnormal conditions.
From memory draw the 345KV Switchyard.
The “Front Bus” supplies power to which transformer(s)?
The “Rear Bus” supplies power to which Transformer(s)?
Front Bus - Supplies Safeguards Transformer
Rear Bus - Supplies Startup Transformers 1-1, 1-2 and 1-3.
Switchyard Station Power Transformers EX-50 and EX-51 are powered by?
EX-50 - “E” Bus
EX-51 - “C” Bus
What is the purpose of the Safeguards Transformer Load-TAP-Changer (LTC)?
To maintain Safety Bus Voltage within limits by automatically adjusting Safeguards Transformer output voltage.
Each step of the LTC will change 2400V AC Bus voltage by 15 volts.
Given the Safeguards Transformer LTC controls are in Automatic, describe the potential consequence of placing the Vacuum Interrupter Reset Switch to “RESET”.
Equipment Damage
Explain the required actions for low switchyard battery room temperature.
If <40 degrees, get permission from System Control to supply additional heating to the room.
If <25 degrees, batteries are considered non-functional.
What is the purpose of the Relay House Battery Room exhaust fan and when should it be in operation?
To prevent buildup of hydrogen gas due to charging. The exhaust fan should always be running.
What type of gas is used in the switchyard Gas Circuit Breakers (GCB)?
Sulfur hexafluoride (SF6)
What is the purpose of the Switchyard Motor Operated Disconnects (MOD)?
Which Switchyard disconnects are MOD’s?
Used to disconnect a circuit after the current has been interrupted by the GCB.
26H5 - Main Gen. to/from Switchyard.
24F1 - Front Bus supply to Safeguards Transformer.
24R2 - Rear Bus supply to Start-Up Transformer.
All other Switchyard disconnects are manually operated.
What is the purpose of the Gas Circuit Breaker (GCB)?
GCB’s interrupt power in the event of a circuit fault, or to manipulate the Switchyard alignment.
Identify the switchyard location:
25R8
31F7
25H9
25R8 - Bay 25 at Rear 8 GCB
31F7 - Bay 31 at Front 7 GCB
25H9 - Bay 25 at Hub 9 GCB
What are the incoming and outgoing voltages of the Safeguards Transformer?
Input - 345KV
Output - 2400V
What is the purpose of the Switchyard 125V DC system?
Supplies power for the controls, alarms and indications in the switchyard.
Capable of carrying all DC loads for a period of 8 hours in the event of a loss of EX-50/51.
Each Switchyard battery charger is able to supply power to all required 125V DC loads, including charging of the battery.
You walk into the Switchyard Battery Room and notice that both ground indicator lights are dimly lit, what are your actions in response to this condition?
Nothing, this is a normal condition. A grounding light will be bright if there is a ground present.
Which breakers in the Switchyard can be operated from the control room?
25F7 and 25H9, Main Generator/Main Transformer Output breakers.
Who is able to operate Switchyard breakers remotely from the Relay House, or locally at the Breaker?
ITC maintenance personnel only.
What is the expected Switchyard alignment during normal plant operation?
All breakers and disconnects closed with all lines energized.
What is the expected Switchyard alignment after a plant trip?
Immediately after a plant trip GCB’s 25F7 and 25H9 open, once open 26H5 disconnect will be opened allowing 25F7 and 25H9 to be reclosed restoring the alignment of the switchyard.
With the plant offline disconnect 26H5 is the only expected disconnect that will be open.
Which procedure covers alarm acknowledgement?
EN-OP-115-08, Annunciator Response.
What does the Switchyard 120/240V AC system supply power to?
Switchyard air compressors, cabinet heaters, Switchyard lighting, Relay House HVAC and 125V DC Battery Chargers.
Upon a Loss of either EX-50 or EX-51 how is power restored to the Switchyard 120/240 V AC system.
Is this process Make before Break or Break before Make?
You would cross-connect the system using the Bus Tie breaker with the supplied Kirk Key interlock.
This system is a break before make design to prevent cross-tying Bus 1C and Bus 1E through the 240V AC system.
