EDG Logic

Question 1

What are teh EDG Auto-Start Signals?

Answer 1

ECCS Initiation Signal from Core Spray Pump Start Logic
2# DW or -59” (No TD)
Undervoltage on Bus 4kV Bus
Undervotlage on Dash Bus
Main Feed Breaker for Dash Bus Open
BOTH Main and Reserve Feed Breaker to 4kV Bus Open

Question 2

What is the MAXIMUM allowed time for EDG to be fully loaded after auto start?

Answer 2

30 seconds

Question 3

What is the initation sequence for EDG?

Answer 3

Auto Start relay picks up and bypasses all breaker trips except Diff Current
ASR Picks up FSR
FSR sends start signal to EDG and bypasses all trips except Overspee and Diff Current
FSR Seals in

Question 4

What is the condition of the ASR when auto-start signals clear?

Answer 4

Auto Resets

Question 5

How fast must the EDG start on initiation signal?

Answer 5

13 seconds and fully loaded in 30 seconds

Question 6

What is the Starting Sequence for EDG Aux Components?

Answer 6

Start Signal: 
Fuel Priming Pump Starts
Governor Oil Booster Pump Starts
Air Start Solenoid Opens
Red Run Light on in MCR (ONLY THAT START SIGNAL RECEIVED)
DG CWP STARTS

200RPM:
Immersion Heater De-energizes
Fuel Priming Pump Stops
Air Start Solenoid De-energizes

800RPM:
Vent Fan Starts
Field Flashes

900RPM - Ramps to 3300V, Flashing stops - goes to 4160V&60Hz

Question 7

What happens to EDG Auxiliaries on EDG Start Signal?

Answer 7

Fuel Priming Pump Starts
Governor Oil Booster Pump Starts
Air Start Solenoid Valve Opens
Red Run Light Comes on IN MCR
DGCWP Starts

Question 8

What does the EDG Red Run Light in MCR indicate?

Answer 8

Start signal received.

Does not necessarily mean that EDG is running

Question 9

What happens to EDG Auxiliaries at 200RPM?

Answer 9

ESR relay defeats 15 second failure to start relay
Immersion Heater De-energizes
Fuel Priming Pump Stops
Air Start Solenoid De-energizes
90 Sec Timer starts - If Main Lube Oil <21psig after timeout - EDG Trip

Question 10

What happens to EDG Auxiliaries on 800RPM?

Answer 10

Vent Fans Start

Field Flashed from DG 125VDC

Question 11

What is the EDG Shutdown Sequence?

Answer 11

On stop signal (NOT TRIP)
Immediately - Field Excitation removed
6 minute cooldown timer begins - ECR keeps SDR energized fro 6 minutes
After 6 minutes: engine shuts down, DGCWP shuts down and 7 minute fuel rack to 0 time delay
Vent fan keeps running and must be manually secured

Question 12

When does the ASR AND FSR start?

Answer 12

Autostart only

Question 13

What happens during a Rx SCRAM or LOOP when DG is already loaded DG for Surveillances?

Answer 13

Change Droop to 5
Adjust DG Frequency to 60 Hz and voltage to 4160Hz
IF EDG WERE TIED TO GRID FOR SURVEILLANCE WHEN AUTO START SIGNAL IS RECEIVED, THE ONLY CHANGE WILL BE THE BYPASSING OF SELECTED ENGINE AND BREAKER TRIPS

Question 14

What breaker interlock exists for the 2/3 EDG?

Answer 14

Cannot be closed on both 23-1 and 33-1 at same time

Question 15

What is the sequence of occurence for 2/3 Breaker on units with LOOP/LOCA?

Answer 15

Don’t Close on me with ECCS on thee!

If U2 experiences a LOOP but no LOCA, EDG will start and close on U2.
If U3 then has LOOP LOCA, EDG will divorce 2 and close on U3;
If U2 then has LOCA, EDG will divorce U3 and run unloaded until Keylock switched by Operator

Question 16

What Permissives are in place in order to auto close breaker for EDG?

Answer 16

C/S in MCR NAT
FB Open at 4kV required for EDG Output breaker to close
MFB open at 4kV-1 sends auto start signal to EDG - not permissive to close
4kV-1 must ACTUALLY be UV
4kV-1 cross tie breaker open
EDG breaker or 4kV-1 bus not locked out
EDG must be running at correct voltage and frequency

Question 17

What is the 23-1/33-1 x-tie interlock?

Answer 17

If 2/3 EDG is on EITHER BUS - 23-1 x-tie breaker will not close unless bypass switch at 23-1 is in bypass
If x-tie is closed, 2/3 EDG will close on to EITHER unit and x-tie will auto open

This is similar for the 24-1/34-1 x-tie

Question 18

What is the ECCS Pp sequence and when is it in effect?

Answer 18

2A LPCI, 5 seconds later 2B LPCI, 5 seconds later 2A CS.

THIS IS ONLY IN EFFECT WHEN EDG Breaker closed - if not all start immediately

Question 19

What is the logic for the breakers between 4kV and 4kV-1 buses and EDG?

Answer 19

If MFB at 4kV-1 opens, auto-starts EDG

If FB at 4kV opens, permissive for EDG to close onto bus

Question 20

What happens during an EDG Bus Overcurrent condition?

Answer 20

If EDG is autostarted and carrying bus, then Bus have overcurrent, EDG WILL NOT SHED FROM BUS
If it is NOT tied to the bus, output breaker will be prevented from CLOSING onto bus

Question 21

What happens if the Local Pushbutton Control Switch on EDG Output Breaker?

Answer 21

Byspasses MCR control switch, synchroscope swithc, and HACR and the interlock preventing simultaneous closure on both units for 2/3 EDG

Question 22

How long does the EDG have to reach 200RPM before lockout on multiple starts/failures to start?

Answer 22

15 seonds - about 4 seconds per try

Question 23

Which Engine Trips are bypassed on Fast Start?

Answer 23

Low Water Pressure
Crackcase Pressure
Hot Engine
Oil Pressure

Question 24

Which Engine/Breaker Trips are NEVER Bypassed?

Answer 24

Overspeed
DG Diff Current
Ground Fault
Hi Diff Current (Breaker)