.AR Elect. PK PN NK NN (Welch's Highlighted Notes) Flashcards
1
Q
PK:
- How many independent subsystems?
- Normal Operating Voltage?
- What is the required capacity/time and the minimum temperature required for PK? (on a loss of charger)…
A
- Four independent subsystems (PKA, PKB, PKC and PKD).
- Subsystem consists of battery, charger, control center and distribution panel
- Normally operates at ~ 135 VDC.
- Bus voltage limits are 129.0 - 139.8 VDC
- Battery float voltage is normally 130.2 - 135.0 VDC
- Equalizing mode max voltage 139.8 VDC
- Capacity: supply required loads for 2 hours (loss of charger) at a minimum temperature of 60°F in the battery room.
2
Q
PK:
- Battery rooms have what type of Q-Class of exhaust fans for Temp/H2 control?
- What is its suction and discharge path to?
- What ESFAS signal(s) start the Essential fans?
- What normally cools DC Equipment Rooms?
- Control Bldg Normal AHU normally takes suction from where?
- What cools the DC Equipment and Battery rooms in a SIAS or LOP?
A
Control Building HVAC (Support System)
- Battery rooms have normal and essential exhaust fans (Temp / H2 control).
- Suction from battery room / discharge directly to atmosphere.
- Essential fans start on SIAS/LOP
- DC Equipment Rooms normally cooled by ESF Switchgear Room Normal AHU (WC).
- Control Building Normal AHU normally takes suction on each DC equipment room.
- SIAS or LOP: DC Equipment Room Essential AHUs (EC) cool DC Equipment and Battery rooms.
3
Q
PK:
Battery Chargers:
- How many normal & backup chargers per train
- list the Interlock(s)…What does it prevent?
- PK chargers are powered from?…
- Can the chargers be operated in parallel? why?
- Are chargers Load Shed? If yes, how fast (seconds) do they reclose?
- What happens to the MCC contactor supplying the charger? can it be operated locally?
A
Class 1E 125 VDC Battery Chargers
- 1 normal charger per load center and 1 back-up charger per train.
- Mechanical interlock prevents aligning back-up charger to both control centers
- Powered from PHA/PHB
- Chargers cannot be operated in parallel (may cause damage).
- Chargers load shed by BOP-ESFAS, reclose in 5 seconds.
- Opens MCC contactor supplying the charger, can be operated locally
4
Q
[PK system Ground Detection & MCR Indications]:
Ground Detection:
- Does PK alarm in MCR?
- Color of light at control center? Resets locally?
- Is PK grounded or ungrounded? Why?
MCR Indications:
- List MCR PK meters…
- The Battery Amps (gauge needle) goes To the right of zero… when it’s charging or discharging?
- What do the volts indicate about the output breaker?
- What are the 2 colors of the Back-up charger MCR indication lights? Which color shows which bus the spare charger is aligned to.
A
Ground Detection
- MCR alarm.
- White light lit at control center. Reset locally.
- Ungrounded system (Increased reliability. Need negative and positive ground to degrade the system.)
MCR Indications
- 125Vdc bus voltage
- Battery Amps (To the right of zero when discharging)
- Charger Amps/volts (volts will indicate if output bkr is tripped)
- Back-up charger lights (Red/Green). Red light will show which bus the spare charger is aligned to.
5
Q
PK:
State the PK MCR Alarms and its SESS Alarms (if any)…
A
125V IE CC M41 CHGR A/AC PNL D21 TRBL Alarm (each board has this alarm)
- Control center under voltage, ground or breaker trip
- Battery Charger problems (over or under voltage, AC supply voltage low, charger failure or reverse current)
- Distribution Panel overload
125V DC 1E CC M41 BAT BKR SESS Alarm (each board has this alarm)
- WHITE section (SEIS) LIT if Breaker Not Closed or inoperable (No SEAS alarm)
6
Q
PK:
Transfer Switches (App. R)
- What do they isolate for the Battery Chargers (Train A or B?) (Where is the switch located?)
- What do they isolate for the Batteries (Train A or B?) (Where is the switch located?)
- It also isolates the A Battery from which circuit breaker? (Where is the switch located?)
A
Transfer Switches (App. R)
- Isolates load shedding and sequence permissive relays, B01 voltmeters and ammeters for B train Battery Chargers (B, D, BD) (Switch is located at the MCC that supplies the charger)
- Isolates MCR breaker controls, voltmeters and ammeters for B train batteries (B, D). (Switch located at 125VDC Control Center)
- Isolates A Battery from the MCR circuit breaker switch (Switch is located on control center PKA-M41)
7
Q
PK:
- PK is control power to what equipment? ( and what happens if power is lost?…)
- PK provides DG control power and field flashing…
- What happens to DG on loss of power?
- If DG was running prior to loss of power, what happens to the DG engine and the output breaker? why?
- What happens to the Turbine Driven Aux Feedwater (TDAFW) MOVs and controls if PK is lost with AFA-P01 running?
- PK chargers power (thru inverters) SI-SDC isolation valves… Can the charger alone power these valves?(SIC-UV-653 & SID-UV-654)
- How does PK support the class inverters? If PK is lost, does the inverter Auto Transfer? (…where to?)
A
(PK) Supported Systems
- Control power to class switchgear and load center breakers and relays (non-functional if power lost)
-
DG Control power and field flashing.
- Loss of power: DG is not capable of starting.
- If running prior to the loss, the engine would trip but the output breaker would remain closed (no control power).
- TDAFW MOVs and controls
- If DC power is lost with AFA-P01 running, it may trip on over speed.
- SI: Supplies (thru inverters) SDC suction isolation valves.
- Charger alone cannot provide sufficient power to operate SDC suction MOVs. Battery must be aligned (UV-653/654).
- DC source to the class inverters. If lost, inverter auto transfers to the AC supply.
8
Q
(PK) LCO 3.8.4 DC Sources – Operating (Modes 1-4)
- List the DC trains and its sub-channels…
- What does each channel (normal or backup) include?
- What makes a DC Bus operable?
- If 1 Charger INOP…
- LCO time in hours if 1 DC electrical subsystem INOP (reasons other than condition A)?
- LCO time if both DC power systems INOP? (can it be entered voluntarily?)
- SR 3.8.4.1: Terminal voltage ≥ ?
- Based on what? Min float voltage per cell?
- LCO 3.8.5 (shutdown) requires what type of source (DC or AC?) to support which LCO #? (Same actions as 3.8.2?)
A
(PK) LCO 3.8.4 DC Sources – Operating (Modes 1-4)
- Train A and Train B DC electrical power subsystems
- Train A (Channel A and C) / Train B (Channel B and D)
- Each channel includes 125 Vdc bus, battery bank, and charger (normal or back-up)
- Operable: all batteries and respective chargers operating and connected to the associated DC bus(es).
-
One Charger inoperable:
- Restore terminal voltage within 2 hours
- Verify float current ≤ 2 amps every 12 hours (battery is re-charged, battery declared inoperable if not met)
- Restore the charger within 72 hours or RICT
-
2 hours or RICT: One DC electrical power subsystem inoperable for reasons other than Condition A (one charger inoperable).
- Example: two chargers inoperable on same train or battery inoperable
- Both DC power subsystems inoperable: restore one within 1 hour OR RICT (cannot voluntarily enter)
- SR 3.8.4.1: Terminal voltage ≥ 130.2 Vdc
- Based on the nominal design voltage of the battery. Consistent with the minimum float voltage (2.17 Vdc per cell) times the number of connected cells or 130.2 V for a 60 cell battery at the battery terminals.
- LCO 3.8.5 (shutdown) requires DC source to support LCO 3.8.10 (same actions as 3.8.2)
9
Q
(PK) LCO 3.8.6 Battery Parameters:
- Battery limits to be Operable?
- Float current is ≤ ? amps (…not required to be met if terminal voltage is low)
- Cell float voltage is > ? Volts.
- Electrolyte level ≥ ? mark on battery cell jar.
- Pilot cell temperature is ≥ ?°F.
- Battery capacity is ≥ ?% (test discharge)
-
Immediately declare Battery inoperable (& enter LCO 3.8.4 condition B):
- Cell float voltage ≤ ? Volts and float current > ? amps.
- Or if what conditions/parameters not met?
A
(PK) LCO 3.8.6 Battery Parameters:
- Batteries shall be within limits when required to be operable.
- Float current is ≤ 2 amps (not required to be met if terminal voltage is low)
- Cell float voltage is > 2.07 V.
- Electrolyte level ≥ level indication mark on battery cell jar.
- Pilot cell temperature is ≥ 60°F.
- Battery capacity is ≥ 80% (test discharge)
-
Immediately declare Battery inoperable (enter LCO 3.8.4 condition B):
- Cell float voltage ≤ 2.07 V and float current > 2 amps.
- Or other conditions not met (parameters not restored in time)
10
Q
(PK) LCO 3.8.9 Distribution Systems – Operating (Modes 1-4):
- List the trains that shall be operable…
- Can a DC subsystem be considered OPERABLE if it’s energized (@ proper voltage) from its battery or charger?
- How long to restore (time in hours)?
A
(PK) LCO 3.8.9 Distribution Systems – Operating (Modes 1-4)
- Train A and Train B AC, DC, and AC vital instrument bus electrical power distribution subsystems shall be operable
- Operable DC electrical power distribution subsystems require the associated buses to be energized to their proper voltage from either the associated battery or charger.
- All 125Vdc Control Centers and Distribution Panels are required.
- Restore in 2 hours or RICT
11
Q
(PN) Class 1E Inverters:
- Includes which transfer switches?
- List control centers?…
- Bus voltage limits?…
- Frequency range?…
A
(PN) Class 1E Inverters:
- Includes both static and manual transfer switches
- Inverters powered by associated 125 Vdc PK Control Center (PKA-M41/PKB-M42/PKC-M43/PKD-M44)
- Converts (inverts) 125 Vdc to 120 Vac
- Bus voltage limit: 118 - 126 Vac
- Frequency: 59.5 - 60.5 Hz
12
Q
(PN) Static Switch:
- Electronic, solid state assembly.
- On loss of normal power (inverter), does it auto transfer?….
-
Does it Auto transfer back?…
- which 2 buttons pressed to transfer manually?…
-
Auto transfers to the voltage regulator:
- ?…
- ?…
- ?…
-
Auto transfers to the voltage regulator:
- Green light – means…?…
- Amber light – means…?…
A
(PN) Static Switch:
- Electronic, solid state assembly.
- On loss of normal power (inverter), automatically transfers the distribution panel to the voltage regulator.
- Does NOT transfer back automatically.
- Distribution panel can be manually transferred by pushing one of the two pushbuttons:
- INVERTER TO LOAD (Aligns to the inverter)
- BYPASS SOURCE TO LOAD (Aligns to the voltage regulator)
-
Auto transfers to the voltage regulator:
- Loss of the square wave to the harmonic filter.
- Low inverter voltage to the static switch (~50% voltage)
- Inverter output overload (120% inverter load ~200 Amps)
- Green light – INVERTER SUPPLYING LOAD
- Amber light – BYPASS SOURCE SUPPLYING LOAD
13
Q
(PN) Voltage Regulator (480/120Vac regulating XFMRs):
- Are they backup or normal?
- Power: ? (MCCs…)
- MCC contactor is load shed on what?… recloses?…
A
(PN) Voltage Regulator (480/120Vac regulating XFMRs):
- Backup power supply for each channel
- Power: PHA/PHB
- MCC contactor is load shed on a LOP, contactor recloses 5 seconds after power restored
14
Q
(PN) LCO 3.8.7 Inverters – Operating (Modes 1 – 4)
- Train A and Train B inverters shall be operable in which modes?…
- ?…
A
(PN) LCO 3.8.7 Inverters – Operating (Modes 1 – 4)
- Train A and Train B inverters shall be operable in Modes 1-4
- One inoperable - 7 days or RICT
- If PN is de-energized, immediately enter LCO 3.8.9 (3.0.6 exception)
- > 1 inverter inoperable – restore in 1 hour or RICT (cannot voluntarily enter)
- Operable inverter: AC vital instrument bus to be powered by the inverter with output voltage and frequency within tolerances, and power input to the inverters from a 125 Vdc battery.
- One inverter may be disconnected from its associated DC bus for ≤ 24 hours to perform an equalizing charge if:
- Bus is energized from its Class 1E constant voltage source regulator; and
- All other buses are energized from their associated operable inverters.
- LCO 3.8.8 (shutdown) requires inverters to support LCO 3.8.10 (same actions as 3.8.2)
- If inverter is inoperable (Cond A entered):
- Do not perform planned maintenance on associated train DG
- Do not perform planned maintenance on another RPS/ESFAS channel that puts that channel in trip
15
Q
(PN) LCO 3.8.9 Distribution Systems – Operating (Modes 1 – 4):
- ?…
A
(PN) LCO 3.8.9 Distribution Systems – Operating (Modes 1 – 4):
- All four boards required.
- Operable 120Vac board: energized to proper voltage from the inverter OR voltage regulator.
- One 120V bus inoperable – Restore in 2 hours or RICT
