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Systems > MA/MB/NA - Main Generation to 13.8kV > Flashcards

MA/MB/NA - Main Generation to 13.8kV Flashcards

Purpose and Operation of the main generation, excitation/regulation, and non-class 13.8 kV

1
Q

What is the purpose of the Main Generation system?

A

-Converts mechanical energy into electrical energy.
-House loads through the Aux transformer
-To the grid from the Unit transformers

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2
Q

What are the main components of the Main Generation system?

A

Main Generator, Isolated Phase (isophase ducts), Main Transformer Bank, Aux Transformer

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3
Q

Describe the generator

A

turbine driven, four pole, synchronous, alternating current generator

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4
Q

What are the major components for the main generator?

A

Generator Casing, Stator, Rotor, and the Collector

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5
Q

What are the end shields?

A

They are on both ends of the generator and contain the bearings (journal) that hold up the rotor and are split horizontally proving a path for seal flow

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6
Q

What components are a part of the generator casing?

A

Stator Frame, End shields, Excitation dome, and Lower frame extension

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7
Q

What makes up the components of the excitation dome?

A

Generator Hydrogen Distribution tubes and the hydrogen coolers

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8
Q

What is the purpose pf the Lower Frame Extension?

A

has the mounts for the High Voltage Bushings to the isophase Buses

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9
Q

What is the purpose of the stator?

A

It generates the voltage ( 24kV) that is supplied to the Main, Auxiliary, and Power Potential Transformers

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10
Q

Describe the Stator

A

-The stator is a winding of insulated copper bars that form a ring.
-It interacts with the rotating magnetic field from the rotor windings and supplies voltage to the High voltage Bushings

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11
Q

How is the stator cooled?

A

The stator bars are hollow to allow deionized water to flow through them from inlet and outlet headers/hoses

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12
Q

What is the purpose of the rotor?

A

Produces the required magnetic flux to interact with the Armature (stator) windings to make voltage & current

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13
Q

What are the major components of the rotor?

A

Field Windings, Retaining rings, slip ring Bearing journal (drive end & collector end), and the rotor field winding cooling fans

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14
Q

What is the purpose of the collector?

A

It applies the DC voltage to the rotor field windings to induce the magnetic field

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15
Q

How does the collector operate?

A

It applies the DC voltage through its carbon brushes to the rotor’s slip rings

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16
Q

How is the collector housing cooled?

A

A cooler fan that Normal Chilled Water (WC) flows through

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17
Q

What is the purpose of the isolated phase bus?

A

Conducts power from the main generator to the Main & Auxiliary Transformers

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18
Q

How do the isophase buses operate?

A

They are isolated from each other & the environment. It is an aluminum conductor supported by porcelain insulators within a dust/water tight enclosure

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19
Q

How are the Isophase ducts cooled?

A

Cooled by forced air from the Isophase Bus Duct Cooling system (CE)

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20
Q

What provides cooling for the Isophase Bus Duct Cooling system (CE)?

A

Turbine Cooling

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21
Q

What is the purpose of the Main Transformers?

A

Steps up the 24kV from the main generator to the grid @ 525kV

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22
Q

How is the main generator isolated?

A

The primary windings are directly connected to the Main Gen.
Secondary windings: 2 output breakers “8” & “5”, a motor operated disconnect

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23
Q

Explain the difference between disconnects and breakers

A

Disconnects are only for isolation

Breakers can be used for isolation but also have protection features

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24
Q

High Voltage Bushings

A

Connect the secondary windings of the Main Transformers to the SRP switchyard

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25
Q

Neutral Bushing

A

Connects the transformer to ground to minimize fault currents

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26
Q

Low Voltage Bushing

A

Connects the 24kV output from the generator to the primary winding of the Main Transformer

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27
Q

Bushing Potential Device

A

Steals a small amount of 60 Hz 115 Volt power through the Condenser Bushing to power transformer auxiliary equipment
(heaters)

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28
Q

Electronic Temperature Monitor (ETM)

A

Each Main Transformer has one to monitor winding temperature & Top Oil Temperature.
Also controls the operation of the transformer’s cooling banks

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29
Q

How do you read the Electronic Temperature Monitor (ETM)?

A

The display scrolls through channels every 2 sec. for the values.

red LED indicated a set value has been exceeded

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30
Q

What are the set points for the phases of cooling for the main transformers?

A

When the transformer get power “flash-the-field”

Between 70-75 degrees Celsius temp

Over 75 degrees Celsius Winding temp

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31
Q

For the Main Transformers, when does each group of fans and pumps turn on?

A

First group turns on at “flash-the-field” / when it first gets power

winding temp 70-75 Celsius the second group turns on

Over 75 Celsius 3rd group turns on

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32
Q

Constant Oil Pressure System (COPS)

A

-Tank mounted to the top of the transformer which allows for the volume changes due to temperature with the oil.

-Desiccant breather and vents air

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33
Q

How does the conservator tank work?

A

It acts as a surge tank for the oil within the transformer, while keeping the oil isolated from atmosphere
- Tank level is measured by a float, positioned below the bladder, that is attached to a gauge near the tank
- There is a pressure gauge which shouldn’t move under normal conditions
-The desiccant keep air going into the bladder moisture free

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34
Q

Describe the purpose and function of the Mechanical Pressure Relief Device.

A
  • A spring loaded valve that will actuate to relieve excess pressure that may build inside the transformer.
  • Actuates and raises the mechanical flag. Sends an alarm to the CR and will reseat
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35
Q

Describe the purpose and function of the Sudden Fault Pressure Monitor.

A
  • Monitors for any pressure surges due to internal faults. Has 3 channels
  • Power status light, fast pressure light, and reset switch (one per channel)
  • Reset switch and Alarm Kill switch ( panel common)
  • one channel will cause an alarm in the CR
  • two of three channels will trip that transformer’s isolation breakers
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36
Q

Describe the purpose and function of the Gas Accumulation Detector.

A
  • Will detect accumulations of gas within the oil of the transformer from oil deterioration or oil hot spot heating
  • Normal value is zero
    -Will alarm the Control Room
37
Q

Describe the purpose and function of the Serveron Gas Analyzer.

A
  • not connected to any other system only indication is local & is monitored through a remote website. needs helium gas cylinder
  • Green light for power
  • Blue light is for service, needs to be checked on the site
  • Red, Alarm. Let CR know and check site
38
Q

Describe the purpose and function of the Control Cabinet.

A
  • Norm & Alt power supplies. Lights will indicated what supplies are available ABT
  • Contains switches to control cooling banks and heaters
  • An Alarm panel
  • Main & Startup Transformers gets its supply from 480VAC Load Centers
    -Site Power & Unit Aux gets theirs from 480 VAC MCC
  • Overload devices
39
Q

Describe the purpose and function of the transformer Alarm Panel.

A
  • All transformer alarm panels get their supply power from Non-class 125 VDC Control Power NK
  • lamps for 12 different alarms
  • CR gets a generic alarm panel alarm, AO needed to verify cause
    -Startup Alarm panel testing will alarm ALL 3 Control Room
  • Testing switches in the units send no alarm to CR
40
Q

Describe the purpose of the main generator output breakers.

A

-2 breakers that provide protection trips for faults on the main generator or the grid
- Ability too sync, connect, or disconnect each unit’s generator to/from the grid
- to sync closed “8” to parallel to grid then close “5”

41
Q

Describe the purpose of the motor operated disconnects.

A
  • Will isolate main gen, transformers from the grid for maintenance
42
Q

Describe the setpoints for cooling for the unit Aux Transformer

A

-Top oil < 60C & Windings <70C, “All natural” no pumps or fans
- Oil 60-65 C & Winding 70-75 C All 14 fans stagger start no pumps
- Oil >65 C & Winding >75 C All pumps

43
Q

Describe the Main Generations (MA) on plant start up.

A
  • Pressurize gen with Hydrogen, start stator cooling (CE), turbine up to speed, & apply excitation
  • Field is flashed, Main & Aux Trans get power and systems start cooling them
  • Close “8” increase load to 65 Mw then close “5”
  • Following plant stabilization, main Gen. load is increased & 13.8 kV loads are switch from offsite to Aux Transformer
44
Q

Describe a Load Rejection

A
  • Sudden Loss of load on the Main Generator
    • Partial: load drops but Generator stays online
    • Total: Rejection that causes Gen. to trip
45
Q

What might happen in the case of a load rejection?

A

Some automatic plant functions include:
- Reactor Power cutback (RPCB) in which certain CEDM groups will drop, reducing power to ~60%
- Steam Bypass Control System (SBCS) by pass the turbine and allowing for steaming to continue to cool the core

46
Q

What would cause a a Fast-Bus Transfer?

A
  1. Main Generator Trips
  2. Aux Transformer Trip
  3. Main Transformer Trip
    NAN-S01/2 should switch to off-site power to maintain power to RCPs
47
Q

Describe the purpose of non-class 480 LC (NG) to support the MA system

A
48
Q

Describe the purpose of Non-class 480 MCC (NH) to support the MA system

A
49
Q

Describe the purpose of non-class 125 VDC control Power (NK) to support the MA system

A
50
Q

Describe the purpose of non-class 120 VAC instrument power (NN) to support the MA system

A
51
Q

Describe the purpose of Uninterruptable Power (NQ) to support the MA system

A
52
Q

Describe the purpose of Normal Lighting (QA) in supporting the MA system

A
53
Q

Describe the impact of losing non-class 120VDC Control Power (NK) to MA

A
54
Q

What is the impact to MA if MB is lost?

A

Main generator trips

55
Q

What is the impact to MA if Stator Cooling (CE) is lost?

A

Main Generator Trip after 70 sec delay

56
Q

What is the purpose of the of Main Generator Excitation and Regulation (MB) system?

A

-supplies the DC current to the rotor for its magnetic field
- Monitors generator output voltage/current & regulated the DC current to the rotor

57
Q

What are the main components of the MB system?

A

-power potential transformers
-Power Conversion room
-EX2100e Control system
-MARK Vle BoP Control System
-HVAC & Fire protection

58
Q

Describe Power Potential Transformer (PPT) cooling

A

ALL NATURAL
- all passive cooling, ambient air cools the radiator fins

59
Q

Describe the PPT functions

A

Taps off between the generator and the Aux Transformer.
-24kV to 1050kV to the AC cabinet

60
Q

Describe purpose and operation of the EX2100e Control System

A

provides DC voltage and current to maintain the rotor’s magnetic field

61
Q

Describe the EX2100e 2 modes of operations

A

Automatic: voltage sensed & the regulator automatically controls the DC Field current to maintain the Generator output voltage

Manual: set to a specific DC field voltage. Will stay constant no matter what the generator output voltage is

62
Q

Describe the Rectifiers

A
  • there are 4 rectifiers. 3 are needed to be in-service, 1 for standby or maintenance
    Convert AC to DC
63
Q

Describe the cooling for the cabinets

A

All cabinets have 2 cooling fans. one in use and one in standby.
- If one is lost the other will automatically start
-if both fans are lost for a rectifier, that power bridge will shutdown and the one on standby will assume the load

64
Q

Where does power for cooling in the power room come from?

A
  • The 2 supplies are non-class 480 VAC LCs and power is routed to a transformer and distribution panel within the PCR. ABT
65
Q

What makes up fire protection for MB?

A

VESDA Fire Detection Systems
&
STAT-X Fire Suppression system

66
Q

How does the VESDA Fire detection system work?

A

will alert CR board 6, trouble alarm, HMI alarm viewer, and a alarm on the Plant Fire Protection System in the SSR
- Indv detectors and air sampling piping in the overhead of each room

67
Q

How does the STAT-X Fire Suppression System work?

A

self-contained canisters in each room.
-system does NOT auto disperse
- extinguishing agent MUST be manually activated by AO or Fire Dept by the stair cases for the emergency exits

68
Q

What is the purpose of the non-class 13.8 kV (NA) system?

A

takes 525kV off-site power and steps down to 13.8 kv to distribute to WRF, to the class 4,16kV buses

Main Generator 24kV to 13.8kV to supply power to the “house loads”

69
Q

What are the major components of the NA system?

A

3 Start up Transformers
AE-NAN-X01/X02/X03

13.8kV Switchgears
NAN-S01-S07

Site Power Transformer and switchgear
AE-ZYN-X05 & AE-ZYN-S08

70
Q

What is Unit 1 Specific for the NA system?

A

Supplies power to WRF, TSC, & 480 VAC Load Centers in the Switchyard

71
Q

What is Station Blackout Configuration?

A

SBOG > NAN-S07 to a unit’s NAN-S03
- This will have power going up to NAN-S05
-Use the FBT path to power NAN-S01
-Go through the ESF transformer powering one class bus

72
Q

What is the purpose of the start-up transformers?

A

Step down off-site 525kV to 13.8 kV for use by the NA system

73
Q

Describe the SRP (upstream) isolations for the startup transformers.

A

-525kV Motor operated Disconnect Switch, operated at the SRP Control Room verified by AO & SRO
vert to horiz disconnect

  • Two 525kV breakers, normally operated by SRP operators. “5” / “8”
    -In an emergency an AO may operate supervised by a CRS,SRO, or SM
74
Q

Describe the PVGS Startup Switchyard (downstream) isloations.

A

-13.8 kV breakers located at each NAN-S05/6
- Manually operated disconnect switches @ the Transformers (turn & raise)

75
Q

Describe the bushings for the Start-up Transformers

A
  • 3 High Voltage bushings connected to the primary winding
  • low voltage bushings connect the secondary windings to the low voltage lines
76
Q

Describe the Windings for the Start-up Transformers

A

-One Primary winding (H) where all 3 high V phases comes in

  • Two 13.8 kV Secondary Windings (Y & Z)
  • One 13.8 kV tertiary winding that dampens harmonics & reduces the severity of ground faults
77
Q

What is the downstream output of the start-up transformers?

A

Each Start-up transformer has TWO 3-phase 13.8 kV outputs

78
Q

Describe the setpoints and cooling for the startup transformers.

A

Winding <70 C All Natty pumps/fans secured

winding 70-75 C 1 fan bank & 1 pump starts

Winding >75 C 2nd fan bank & 2nd pump starts

POWERED FROM SY 480 LC NGNL43 & NGNL44

79
Q

What is different with the alarm panel @ the startup transformer vs the PA transformers?

A

The Alarm panel on the startup transformers will alarm ALL 3 CRS when the switch is put into the ‘TEST’ position

80
Q

What is and what are the consequences of an Open Phase Condition?

A

-When one or two phases of three become disconnected
-*****

81
Q

What could cause an Open Phase Condition (OPC)?

A

-Breaker Poles failing to open or close
- Failing Transformer bushings
-Line insulators breaking
- Improperly connected conductors

82
Q

What equipment is used for Open Phase Protection?

A
83
Q

What is the purpose of the 13.8 kV non-class Switchgear?

A

-buses NAN-S01-S07
- distributes power to non-safety loads, non-class 4.16 kV (NB), and WRF

84
Q

What is the difference between NAN-S01-S06 and NAN-S07?

A

NAN-S07: only operated locally
-their handswitch flag MATCHES the position of the breaker
- SBOG output breakers are operated from SBOG Control Panels
- the tie breakers to each unit are located on S07

NAN-S01-6: Normally operated from the Control Room
- Can be operated in the event of an emergency
-Handswitch flags indicate the last position the handswitch was taken to during TESTING.

85
Q

What is a 86 lockout indicated by?

A
  • An orange flag on the 86 lockout handswitch
    -86 lockout Handswitch turned 45 degrees
  • breaker’s whitelight is out
  • green light is brighter than normal
86
Q

What is the breaker labelled ‘DA’ for inside the breaker panel?

A

Opening the ‘DA’ breaker will remove control power from the entire circuit, and all indicating lights will go out

87
Q

What are each of the following fuses for:
UC / UT / UA / UL

A

-UC ‘Closing’ supplies the power to the closing circuit and the green/clear lights

-UT ‘Tripping’ power to the tripping circuit Red/White lights

-UA ‘Remote’ or ‘UX’ connects breakers control circuit to the CR and supplies power to the CR breakers indicating lights

-UL ‘lifting’ power to the connector for the breaker for the racking motor

88
Q

What must happen in order for a Fast-bus Transfer to occur on NAN-S01 & NAN-S02?

A
  • Either of the initiating events for a FBT:
    -Trip the Main Gen. or Unit Aux T.
    -Switch in the CR must be in ‘AUTO’
    -neither NA bus can have an 86 lockout
  • sync check
    -crosstie breaker closes before the breaker between the bus and transformer opens
89
Q
A

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