201.41 ESF Load Sequencers Flashcards Preview

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Flashcards in 201.41 ESF Load Sequencers Deck (14):
1

201.41 ESF Load Sequencers


Function of ESF Sequencer

Sequentially start ESF loads during emergency conditions

Prevent overloading of the emergency bus and associated Standby Diesel Generator (high starting currents)

2

201.41 ESF Load Sequencers


Location and power supplies of Sequencers

EAB 10', separate rooms south of elevator

Respective Class 1E 125 VDC Switchboard:

E1A11 - A train

E1B11 - B train

E1C11 - C train

3

201.41 ESF Load Sequencers


What are the diferent sequencer modes?

Mode I - Safety Injection Signal

 

Mode II - Loss of Off-Site Power (LOOP)

(Undervoltage on the associated ESF Bus)

 

Mode III - Safety Injection with LOOP

(Mode I plus Mode II)

4

201.41 ESF Load Sequencers


Mode I initiation by:

Initiated by the simultaneous receipt of any four or more of six Safety Injection signals generated by the Engineered Safety Features Actuation System.

5

201.41 ESF Load Sequencers


Mode II initiation by:

Initiated by the simultaneous receipt of any two out of four 4.16kV ESF Bus:

Undervoltage

Sustained degraded voltage

Degraded voltage with Safety Injection

6

201.41 ESF Load Sequencers


Mode III initiation

Initiated by the existence of both Mode I and Mode II conditions.

Both simultaneously,

Either Mode I or II followed by the other

Mode I with the DG output breaker closed for > 1 sec.

If the DG is running in parallel with off-site power the SI signal will trip the DG output breaker, unless the DG is in local control

7

201.41 ESF Load Sequencers


Controls for ESF Sequencer in Control Room

Mode II Manual Actuation

(simulates all 4 bus UV signals)

Sequencer Reset

(resets sequencer if all conditions satisfied)

(CP-003)

8

201.41 ESF Load Sequencers


Function of Load Sequencer Key Switches

Mode I Logic key switch allows operator to reset Mode I Logic Present signal.

(if not reset, a subsequent Mode II signal would cause Mode III)

 

D/G Emergency Trip and D/G Breaker Closure key switches

allow simulation of those conditions

9

201.41 ESF Load Sequencers


Actions (or conditions) required to reset sequencer

Reset all SI signals

Reset all UV signals

Verify automatic loading sequence completed or aborted

Depress sequencer reset button

Must use Mode I Logic Reset keyswitch to clear Mode I logic

10

201.41 ESF Load Sequencers


If DG is operating in parallel, what will a SI signal result in?

Trip the DG output breaker w/in 1 sec, resulting in Mode I actuation not a Mode III

11

201.41 ESF Load Sequencers


After a LOOP, the DG output breaker will not close until:

Proper voltage / frequency

6 sec time delay from LOOP signal removed

Breakers open for equipment that recieves a bus strip signal

(fails to open, or open signal to seq fails, sequencer locks up)

(DG breaker closed is Mode I and II permissive)

12

Equipment that starts on Mode I actuation

HHSI - 6 sec

LHSI - 10 sec

CS - 15 sec (if RCB > 9.5 psig) momentary 2 sec signal

RCFCs - 15 sec

CCW - 20 sec

ECW - 25 sec

AFW - 30 sec

CR Emerg. HVAC / Makeup - 35 sec

Ess Chilled Water - 35 sec

STDBY Ess Chiller - 35 sec

CS - 40 sec (if RCB > 9.5 psig / not yet running) latched

Ess Chiller - 240 sec

 

13

201.41 ESF Load Sequencers


Equipment that starts on Mode II actuation

480 VAC Buses - 1 sec

RCFCs - 15 sec

CCW - 20 sec

ECW - 25 sec

AFW - 30 sec

CR Emer HVAC - 35 sec

Ess Chilled Water - 35 sec

STDBY Ess Chiller - 35 sec

Ess Chiller - 240 sec

14

201.41 ESF Load Sequencers


Equipment that starts on a Mode III actuation

480 VAC buses - 1 sec

HHSI - 6 sec

LHSI - 10 sec

CS - 15 sec (if RCB > 9.5 psig) momentary 2 sec signal

RCFCs - 15 sec

CCW - 20 sec

ECW - 25 sec

AFW - 30 sec

CR Emerg. HVAC / Makeup - 35 sec

Ess Chilled Water - 35 sec

STDBY Ess Chiller - 35 sec

CS - 40 sec (if RCB > 9.5 psig / not yet running) latched

Ess Chiller - 240 sec