Non-Class 13.8kv Power (NA)

Question 1

Where does the Non-Class 13.8kv system get its power from and where does it send it?

Answer 1

•Takes power from 525kv offsite power via the startup transformers
•Takes power from the Main Generator via the Unit Aux XFMR

Off-Site power gets sent to:
•Sends it to WRF
•Gets sent to the ESF XFMR(NB) then to the Class 4.16kv system(PB)

Main Generator Power gets sent to:
•NAN-S01 and NAN-S02

Question 2

What does the Non-Class 13.8kv system consist of?

Answer 2

•Three common unit start-up transformers (AE-NAN-X01,2,3)

•13.8kv Switchgear
NAN-S01,2,3,4,5,6,7

•1 Site Power XFMR and associated switch gear
-AE-ZYN-X05 (XFMR)
-AE-ZYN-S08 (Switchgear)

Question 3

Describe Normal power flow path
refer to drawing

Answer 3

Start-up XFMR’s—>NANS05&6—>NANS03&4—>ESF XFMR—>PBAS03&PBBS04

Unit Aux XFMR—>NAN-S01&S02–>Norm. XFRM’s NBNX01&2—>NBNS01&S02

Question 4

What else does Unit 1’s NANS05&S06 supply power too other than NAN-S03&S04?

Answer 4

Unit 1’s NANS05- also supplies 13.8kv to:
•WRF
•480v LC to Switchyard

NAN-S06 also supplies 13.8kv to:
•WRF
•Technical Support Center(TSC)
•480v LC to Switch Yard

Question 5

What else does NAN-S01&S02 supply power to other than the Non-Class (NB) system NBN-S01&S02

Answer 5

NAN-S01 also supplies 13.8kv too:
•RCP1A
•RCP1C
•CWP1B
•CWP1A
•3 diff 480 LC (NG)

NAN-S02 also supplies 13.8kv to:
•RCP1B
•RCP1D
•CWP1C
•CWP1D
•3 diff 480v LC (NG)

Question 6

Outage Flow path

Answer 6

•When in outage the Main Generator is secured and cannot supply power to Class loads

•So a cross-tie is closed connecting NAN-S03&S04 to NAN-S01&S02

Question 7

Station Black Out Flow path

Answer 7

Both Emergency Diesel Engines Failed
•During a Black Out a SBOG will be started, powering NAN-S07 with 14kv

•NANS07 can then transfer power to:
-ESF —>Class Loads
-NANS03–> NANS01 and NANS05

Question 8

What’s the Purpose of the (Common Unit) Start-Up transformers NANX01,2,3 ?

Answer 8

•Takes off-site 525kv power and step it down to 13.8kv for use by the NA system.

Question 9

Describe the isolations for the Start-Up transformers
theres upstream and downstream sides

Answer 9

-SRP Switchyard(Upstream)
•525kv MOD (Verified by AO and SRO)
•Two 525kv Breakers

-PVGS Start-Up Switchyard(Downstream)
•13.8kv breakers located in NANS05&6
•Manual operated disconnect at the SU XFMR itself

Question 10

How does the manual disconnect at the Start-Up XFMR work?

Answer 10

•Connected horizontally

•When disconnecting the disconnect blade with rotate axially 90deg to break contact w/ the bus and then raise vertically

Question 11

How many Bushings does the Start-Up XFMR have?

Answer 11

The SU XFMR has 2:

•High Voltage Bushing connect the incoming 525kv to the primary windings

•Low voltage bushing connect the secondary windings to the outgoing 13.8kv lines

Question 12

Describe Start-Up transformer Windings

Answer 12

• One 525kv primary winding connected to the SRP Switchyard (H winding)

•Two 13.8kv secondary windings (Y&Z winding)

•One 13.8kv tertiary winding (X winding)
-Dampens harmonics
-Reduces severity of ground faults

Question 13

How does the Start-Up XFMR’s route normal power to NAN-S05&6 for each unit ?

Answer 13

U1:
S05-X03
S06-X02

U2:
S05-1
S06-3

U3:
S05-2
S06-1

Question 14

How does the Start-Up XFMR route ALT power to NAN-S05&6?

Answer 14

U1 ALT power:
S05&6: NAN-X01

U2 ALT power:
S05&6: NAN-X02

U3 ALT power:
S05&6: NAN-X03