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.AR LOIT Systems: Welch's Highlighted Notes > .AR Elect. Non-Class dist. (Welch's Highlighted Notes) > Flashcards

.AR Elect. Non-Class dist. (Welch's Highlighted Notes) Flashcards

1
Q

Start-up XFMRs (NAN-X01, X02, X03):

  • Location of SU XFMRs?…
  • How many Secondary (2°) windings per SU XFMR?
  • State the secondary (2°) winding capabilities?…
A

Start-up XFMRs (NAN-X01, X02, X03)

Located in Startup Switchyard

Each SU XFMR has two secondary windings

  • Each 2° winding supplies power to one intermediate bus (NAN-S05/S06)
  • Each winding capable of supplying alternate power to an additional bus.
  • Each 2° winding sized to supply half the non-Class 1E loads of one unit and two trains of ESF loads (one from another unit) during unit trips or startup/shutdown operation.
    • One Intermediate Bus would have to be on alternate.
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2
Q

Start-up XFMRs (NAN-X01, X02, X03):

  • State the SU XFMRs Cooling system…(What happens at < 70°C, 70°C, >75°C?)
A

Start-up XFMRs (NAN-X01, X02, X03):

SU XFMR Cooling System (2 groups of fans/oil pumps):

  • < 70°C Oil - Natural circulation of the oil. Fans/pumps are not operating. (normally < 70°C, low loading)
  • 70°C Oil – Auto starts first stage Oil pumps / fans
  • >75°C Oil - Auto starts second stage Oil pumps / fans
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3
Q

Start-up XFMRs (NAN-X01, X02, X03):

  • Location?…
  • Explain breakers for U1 and U2/3…
  • What does U1 supply (ONLY U1)?…
A

Start-up XFMRs (NAN-X01, X02, X03):

  • Located in startup switchyard
  • All intermediate bus supply breakers controlled from Unit 1.
  • U2/U3 supply breakers can be controlled from their unit.
  • Only U1 has load side breakers
  • U1 ONLY also supplies:
    • WRF (NBN-S05 and S06)
    • 480V S/U SWYD load centers (NGN-L43 and L44)
    • 480V power to SRP SWYD
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4
Q

Intermediate Buses (NAN-S05 and NAN-S06):

  • What is their Normal & Alternate Control Power for each?…
  • Where are the Manual Transfer switches located?…
  • PMUX:
    • ​Indications are…
    • Controls are…
  • How do you verify breaker positions?
A

Intermediate Buses (NAN-S05 and NAN-S06):

Control power:

  • Manual transfer switches located in NK switchgear room
  • NAN-S05: NKN-_M45_ (normal) or NKN-_M46_ (alternate)
  • NAN-S06: NKN-_M46_ (normal) or NKN-_M45_ (alternate)

PMUX

  • Indications are multiplexed with the controls hardwired. (can lose one or the other)
  • Must verify breaker positions locally.
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5
Q

Switchgear (NAN-S03 and NAN-S04):

  • Normal power supplies?… What’s special about U1 normal supply breakers? U2/3?…
  • Alternate power supplies?…
  • Are they Manual or AUTO transfer?…
  • They normally supply power to…
  • They are backup/standby power for… (when UAT is not available…)
A

Switchgear (NAN-S03 and NAN-S04):

Powered from:

  • Normal: (NAN-S05/S06) (Only U1 has a breaker on normal supply, U2/U3 are hard wired)
  • Alternate: NAN-S01, S02
  • Manual transfer ONLY

Supplies power to:

  • Normal supply to ESF XFMRs.
  • NAN-S01/S02 when the UAT is not available.
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6
Q

Switchgear (NAN-S03 and NAN-S04):

  • Their control power comes from…
  • Do they have overcurrent protection? Location?
  • What type of plant trip senses the Bus voltage and uses it as its input? Is it used for FBT also?
A

Switchgear (NAN-S03 and NAN-S04):

Control power:

  • NAN-S03: NKN-D41
  • NAN-S04: NKN-D42
  • Individual control power breakers (RRCs) located inside each breaker cubicle

Relays

  • Overcurrent protection on feeder breaker (located at NAN-S05/S06)
  • Bus voltage sensed for input into coastdown trip and fast bus transfer logic.
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7
Q

SBOGs (NAN-S07)

  • Where is NAN-S07 located?…
  • Where is its feeder breaker?…
  • Can it supply a Unit is that Unit’s NBN-X03 is faulted?…
  • Which Units it cannot supply at the same time? limitations?…
A

SBOGs (NAN-S07):

  • NAN-S07 (located at WRF). Feeds each Unit’s NAN-S03.
  • Connection is made downstream of the breaker supplying ESF XFMR (NBN-X03).
  • Cannot supply a unit if that unit’s NBN-X03 is faulted
  • Cannot supply U2 and U3 at the same time (cable limitations)
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8
Q

Water Reclamation Facility (NBN-S05 and S06):

  • From which Unit is WRF supplied? How?…
  • On what event do WRF supply breakers Load Shed? This is to prevent what event?
  • Can the buses be Cross-tied?
A

Water Reclamation Facility (NBN-S05 and S06):

  • Supplied from U1 Intermediate busses only via two CT Makeup and Blowdown XFMRs (NBN-X05 and X06)
  • WRF supply breakers load shed (degraded SWYD voltage and U1 SIAS or CSAS signal from BOP-ESFAS).
    • Prevents a “double sequence” event.
  • Buses can be cross-tied.
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9
Q

Switchgear NAN-S01 and NAN-S02:

  • What is their control power for each?
  • Where are the individual control power breakers for each cubicle located?
  • What happens to FBT if control power is lost?
A

Switchgear NAN-S01 and NAN-S02:

Control power:

  • NAN-S01: NKN-D41
  • NAN-S02: NKN-D42
  • Individual control power breakers inside each breaker cubicle
  • FBT lost if control power lost
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10
Q

Fast Bus Transfer (loss of UAT or generator):

  • What are the conditions necessary (permissives) for a FBT to occur on a:
    • Loss of UAT, or
    • Loss of the Main Generator
A

Fast Bus Transfer (loss of UAT or generator):

  • BUS XFR SW in AUTO
  • Generator or UAT trip actuated
  • Early ‘b’ contact for normal supply breaker closed (Normal breaker has started to open).
    • Momentarily in parallel

Fast Bus Transfer (loss of UAT or generator)

* BUS XFR SW in AUTO
* **Generator or UAT trip** actuated
* **Early ‘b’** contact for normal supply breaker closed (_Normal breaker has started to open_).
    * Momentarily in parallel
* Synch Check relay met.
* NO bus lockout.
* Alternate supply voltage available (NAN-S03 or S04) * Synch Check relay met. * NO bus lockout. * Alternate supply voltage available (NAN-S03 or S04)
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11
Q

“Coastdown Trip” of the Generator:

  • When does a “Coastdown Trip” of the Generator occur?
  • Which component are NAN-S01 & S02 kept aligned to for a period of time following a trip?
  • All breakers are Load Shed in a “Coastdown Trip”, except which ones? Why?…
  • On a “Coastdown Trip” how long do normal supply breakers stay closed for, or at what % voltage level drop do they OPEN?
A

“Coastdown Trip” of the Generator:

  • Occurs when generator trips concurrent with a LOOP (no power on NAN-S03, S04)
  • NAN-S01 and S02 are kept aligned to UATs for a period of time following trip.
  • All breakers except the RCPs are load shed (maintains flow to core for as long as possible).
  • Normal supply breakers stay closed for 20 seconds OR < 80% voltage, whichever occurs FIRST.
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12
Q

Normal Service Transformers:

  • What types of cooling do the Normal Service Transformers have?
  • What happens at > 70°C Hot spot temp?
  • What is its control power? It Auto transfers to Alternate… How does it transfer back to normal?
  • List the various forms of protection/relays for the XFMRs?
A

Normal Service Transformers:

  • FA/OA type (Forced Air/Oil Air)
  • > 70°C Hot spot temp – starts four fans (if in AUTO)
  • Control power from NH. (Auto transfer to alternate. Manual transfer back to normal)
  • Protection:
    • Sudden Pressure Relay
    • Transformer differential current
    • Phase and ground overcurrent
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13
Q

Non-Class 4.16 kV Switchgear (NBN-S01 and S02):

  • State the voltage limits for NBN-S01 & NBN-S02…
  • List the different loads for NBN-S01 & NBN-S02…
A

Non-Class 4.16 kV Switchgear (NBN-S01 and S02):

  • Voltage limits 3.74 kV to 4.37 kV

NBN-S01:

A NC Pump

A TC Pump

A PW Pump

B HDT Pump

A & B Cond Pump

B Normal Chiller

NBN-S02:

B NC Pump

B TC Pump

B PW Pump

A HDT Pump

C Cond Pump

C Normal Chiller

E02 Normal Chiller

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14
Q

[Non-Class 4.16 kV Switchgear (NBN-S01 and S02)]

Synch Switch:

  • How many sync switch(es) per Normal feeder breaker?…
  • How many positions does S01/S02 cross-tie breaker Synch Switch has? List them!…
    • It permits what of the S01/S02 tie breaker only (S01C)?
    • What happens when the control switch is returned to normal?
    • What happens if wrong position is selected? What about when taken back to normal?
    • What happens if you overshoot when returning to OFF?
A

Synch Switch:

  • One synch switch for each Normal feeder breaker.
  • S01/S02 cross-tie breaker Synch Switch has 3 positions (S01 XFR / OFF / S02 XFR)
    • Permits closing of the S01/S02 tie breaker only (S01C)
    • Trips the appropriate normal feeder breaker when the control switch is returned to normal.
    • If wrong position is selected, the tie breaker will close. But the wrong breaker will trip when taken to normal.
    • Do NOT overshoot when returning to off, as a trip of the breaker that is supplying BOTH buses will occur.
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15
Q

[Non-Class 4.16 kV Switchgear (NBN-S01 and S02)]

Auto Bus Transfer (FBT):

  • What fault causes a FBT?
  • List the conditions for a FBT to occur…
A

[Non-Class 4.16 kV Switchgear (NBN-S01 and S02)]

Auto Bus Transfer (FBT):

  • Normal Service XFMR fault causes fast bus transfer
    • Transfer Switch in AUTO
    • Normal Service XFMR Fault
    • Normal Supply breaker starts opening (early B contact)
    • Voltage sensed on opposite bus
    • Synch Check relay met
    • No lockout on either bus
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16
Q
  • What is the control power for NBN-S01 & NBN-S02?
  • Where are the individual control power breakers located?
A

Control power (for NBN-S01 & S02):

  • NBN-S01: NKN-D41
  • NBN-S02: NKN-D42
  • Individual control power breakers located inside each breaker cubicle
17
Q

[Non-Class 4.16 kV Switchgear (NBN-S01 and S02)]

480 Vac Non-Class Load Center XFMRs:

  • How many LC’s are powered from NAN-S01/S02?
  • How many LC’s are powered from NAN-S05 and S06 in the SU SWYD?
  • Does each XMFR have a supply disconnect “Kirk Key” interlock?
    • What does this ensure?…
A

[Non-Class 4.16 kV Switchgear (NBN-S01 and S02)]

480 Vac Non-Class Load Center XFMRs:

  • 28 non-class 480 Vac load centers powered from NAN-S01 / S02
  • 2 powered from NAN-S05 and S06 in the SU SWYD
  • Each XMFR has a supply disconnect “Kirk Key” interlock:
    • Ensures 480V supply breaker (is) locked open before mechanical disconnect switch can be opened.

.AR LOIT Systems: Welch's Highlighted Notes (60 decks)

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