125VDC and 240/120VAC Auxiliary Control Power System(EPK/EPF)

Question 1

What is the purpose of the 125VDC and 240/120VAC Auxiliary Control Power System(EPK/EPF)?

Answer 1

The purpose of the 125VDC and 240/120VAC Auxiliary Control Power System is to supply control power to non-safety related equipment and the Operator Aid Computer.

Question 2

What is the system designator for the 125VDC Auxiliary Control Power System?

Answer 2

EPK

Question 3

What is the system designator for the 240/120VAC Auxiliary Control Power System?

Answer 3

EPF

Question 4

What are the major system components of the 125VDC Auxiliary Control Power System?

Answer 4

1. Two 125VDC Batteries
2. Two Normal Battery Chargers
3. One Standby Battery Charger
4. Two 125VDC Distribution Centers

Question 5

What are the designators for the 125VDC Batteries?

Answer 5

CBA

CBB

Question 6

What are the designators for the Normal Battery Chargers?

Answer 6

CCA

CCB

Question 7

What is the designator for the Standby Battery Charger?

Answer 7

CCS

Question 8

What are the designators for the 125VDC Distribution Centers?

Answer 8

CDA

CDB

Question 9

What is the purpose of the 125VDC Battery Chargers?

Answer 9

The Battery Chargers provide the normal power to the 125VDC Distribution Centers(CDA and CDB).

Question 10

Where are the 125VDC Battery Chargers powered from?

Answer 10

The Normal Battery Chargers are powered from Blackout Load Centers:

1. CCA is powered from LXI
2. CCB is powered from LXH

The Standby Battery Chargers is powered from LXC

Question 11

What are the local indications and controls on the Battery Chargers?

Answer 11

1. Output Volts
2. Output Amps
3. FLOAT and EQUALIZE pushbuttons

Question 12

What is the precaution associated with aligning a battery charger to a bus with no battery aligned?

Answer 12

A battery charger is not aligned to any bus unless a battery is connected. The battery chargers lack sufficient voltage stability to serve as the sole power source to a DC system.

Question 13

What is the purpose of the 125VDC Batteries?

Answer 13

1. The 125VDC Batteries provide backup power for the CDA and CDB Distribution Panels.
2. They will automatically assume load on a loss of AC power or a loss of a battery charger.
3. The batteries are normally maintained on a FLOAT charge.

Question 14

What is the capacity of the 125VDC Batteries?

Answer 14

The Auxiliary Control Power Batteries are capable of carrying their associated loads for at least 2 hours.

Question 15

Which Battery Charger is aligned for an Equalizing Charge?

Answer 15

The Standby Battery charger will be aligned to a battery requiring an Equalizing Charge.

Question 16

When does “Cell Reversal” occur?

Answer 16

80-85% of normal battery voltage

Question 17

Can “Cell Reversal” be corrected?

Answer 17

NO

Question 18

What affect can “Cell Reversal” have on equipment?

Answer 18

1. Damage to the remaining cells of a battery bank.

2. Damage to equipment being supplied by the battery.

Question 19

How do we prevent “Cell Reversal”?

Answer 19

1. Minimize drain on the battery
   A. Removed non-vital loads from the DC bus.
   B. Placing AC portions of these systems on alternate power supplies.
   C. Consulting station management for recommended loads to remove from a DC bus.
2. Remove a battery from service when the battery’s voltage drops below 105VDC.

Question 20

What are the typical loads off of the 125VDC Distribution Panels?

Answer 20

1. 600V Non-Essential Load Center Control Power
2. CM System Control Power
3. Exciter Control Power
4. FWPT Control Power
5. Mulsifyre System
6. AFWP Control Power
7. D/G Control Panels
8. D/G CO2 Fire Protection
9. 4160V Blackout Switchgear
10. 125VDC EMC Disconnect Switch
11. Control Rod Drive Control Panel
12. Static Inverters(KXIA and KXIB)
13. Auctioneering Diode that feeds OAC power

Question 21

Where is control power provided from if power from 125VDC Distribution is lost?

Answer 21

CDA normally feeds:

1. Control Power for LXI(600V Blackout Load Center)
2. 4160V Blackout Switchgear
3. CAPT Power

If power is interrupted to any one of these loads, ALL of them will automatically be transferred to a center tap on the 250VDC Battery.

Question 22

What action is required to restore the 125VDC loads back to CDA following a power swap?

Answer 22

When normal power is restored loads can be manually transferred back to CDA by pushing the RESET pushbutton on the Control Power Transfer Cabinet in the Blackout Switchgear Room.

Question 23

What type of ground detection instrumentation/controls are located at each 125VDC Distribution Panel?

Answer 23

1. Ground Voltmeter
2. Ground Indication Lights
3. Battery Voltage to Ground Volt Meter Selector Switch
4. Battery Undervoltage Relay
5. Undervoltage Relay Test Switch(I&E only)
6. Battery Ground Detector Test Switch(I&E only)

Question 24

Where are ground alarms received?

Answer 24

1. Control Room

2. Operator Aid Computer

Question 25

What are the indications of a ground locally at the 125VDC Distribution Panels?

Answer 25

1. The normally dimly lit lights will be brighter for the grounded leg. 2. When the Battery Volt To Ground Mode Selector Switch is taken to either the POS or NEG position it will show the magnitude of the ground on the Ground Voltmeter.

Question 26

What alarms will be generated in the Control Room when operating the Battery Volt To Ground Mode Selector Switch?

Answer 26

NONE | **The switches operated by I&E will produce Control Room alarms**

Question 27

What are the major components in the 240/120VAC Auxiliary Control Power System?

Answer 27

1. Three 125VDC -120VAC inverters 2. Three Automatic Transfer Switches 3. Three Manual Transfer Switches 4. Two 600VAC Voltage Regulators 5. Two 120VAC Distribution Centers 6. Five Panelboards

Question 28

What are the designators for the Static Inverters?

Answer 28

1. KXIA 2. KXIB 3. KUI

Question 29

What is the purpose of the Static Inverters?

Answer 29

The Static Inverters provide a highly reliable source of AC power by converting 125VDC to 120VAC to supply the AC portion of the Auxiliary Control Power System.

Question 30

What are the designators for the 120VAC Panelboards supplied by the Static Inverters?

Answer 30

1. Train A - KXPA 2. Train B - KXPB 3. KUT(OAC Computer Inverter)

Question 31

When a Static Inverter is taken out of service what supplies power to the 120VAC Panelboards?

Answer 31

600VAC is regulated and transformed down to 120VAC as a backup source to KXPA, KXPB, and KUT.

Question 32

What are the local indications at the Static Inverters?

Answer 32

1. AC Volts (upstream of Inverter Output Breaker) 2. AC Amps (upstream of Inverter Output Breaker) 3. Frequency (upstream of Inverter Output Breaker) 4. In Sync Amber Light (lit when the normal and alternate sources are synchronized)

Question 33

What are the power supplies for each Static Inverter?

Answer 33

1. KXIA - CDA 2. KXIB - CDB 3. KUI - CDA/CDB through auctioneering diodes

Question 34

What is the purpose of the Automatic Static Transfer Switch?

Answer 34

1. The Automatic Static Transfer Switch automatically swaps to the alternate source on lower inverter output voltage. 2. Manual swap capability is also provided via pushbuttons on the Automatic Transfer Switch.

Question 35

What are the two positions of the Automatic Static Transfer Switch?

Answer 35

1. Inverter to Load (indicated by amber "Static Sw. in Inverter Position") 2. Alt Source to Load (Indicated by red "Static Sw. in Alt. Source Position")

Question 36

What will happen after an automatic swap of the Automatic Static Transfer Switch if output voltage on the inverter returns to normal?

Answer 36

1. 60 second time delay, then 2. The Automatic Static Transfer Switch will switch back to the inverter when inverter voltage and frequency are normal(Normal Seeking).

Question 37

What is the purpose of the Manual Bypass Switch?

Answer 37

The Manual Bypass Switch provides a means of bypassing the Auto Static Transfer Switch.

Question 38

What are the three positions of the Manual Bypass Switch?

Answer 38

1. Normal Operation 2. Alternate Source to Load 3. Inverter to Load

Question 39

What is the affect of having the Manual Bypass Switch in the NORMAL position?

Answer 39

The Manual Bypass Switch is aligned to the Auto Static Transfer Switch which is supplied by the inverter.

Question 40

What is the affect of having the Manual Bypass Switch in the Inverter to Load position?

Answer 40

Bypasses the Auto Static Transfer Switch and aligns to the inverter directly to the loads.

Question 41

What is the affect of having the Manual Bypass Switch in the Alternate Source to Load position?

Answer 41

This position bypasses the Auto Static Transfer Switch and the inverter. The alignment puts the regulated AC power source to the loads.

Question 42

What are some of the indications on the Manual Bypass Switch?

Answer 42

1. AC Volts (downstream of the Manual Bypass Switch) 2. AC Amps (downstream of the Manual Bypass Switch) 3. ALT Source Low Voltage - Red Light will be lit when the alternate source voltage is low. 4. In Sync - Amber Light will be lit when the normal and alternate sources are synchronized. 5. ALT Source Off Frequency - Light will be lit when the alternate source frequency is not within the proper range of the static inverter. 6. Alternate Source AC Input Frequency Meter

Question 43

What is the purpose of the Manual Transfer Switch?

Answer 43

The Manual Transfer Switch allows for the replacement of the inverter system components online. This switch bypass the inverter, the Auto Static Transfer Switch, and the Manual Bypass Switch.

Question 44

What are the designators for the 120VAC Regulated Panels?

Answer 44

1. KXPA 2. KXPB 3. KUT

Question 45

What are the typical loads off of the 120VAC Regulated Panels?

Answer 45

1. Main Control Boards 2. Main Turbine Control 3. Radiation Monitor Cabinets 4. Smoke and Detection Systems 5. NC Pump Vibration Monitor 6. H2/KG Panel 7. Inverter Control Power

Question 46

What is 240/120VAC Regulated Power used for?

Answer 46

1. Provides regulated power to to Panelboards RPA and RPB | 2. Provides backup power to the inverter Panelboards, KXPA, KXPB, and P-1.

Question 47

What type of interlock is provided on the 240/120VAC Regulated Power input breakers, and why?

Answer 47

A Kirk-Key Interlock is provided between the two panel input breakers and the tie-breaker to allow only 2 out of 3 breakers to be closed at once. This prevents cross tying both sources of 240/120VAC power.