Stator Water

Question 1

What is the purpose of Stator Water Cooling?

Answer 1

Remove heat produced in the main generator stator bars and field rectifiers

Question 2

What provides NPSH to stator Cooling Pumps?

Answer 2

Surge Tanks

Question 3

What is the makeup to the SWC Surge Tank?

Answer 3

Clean demin via the deionizer and manual valve

Question 4

What are teh power sources for teh SWC pumps?

Answer 4

2(3)A: 25(35)

2(3)B: 26(36)

Question 5

What provides the cooling to the SWC system?

Answer 5

Service Water flows through the tubes of the coolers and discharges to 36” service water header

Question 6

How is temperature maintained in SWC?

Answer 6

AO 3-way bypass vlv allows stator cooling water to bypass cooler
TIC senses water temp downstream of inlet TCV and regulates flow from cooler shell side and bypass line.
Measures and controls SWC

Question 7

What happesn to SWC TCV on loss of IA?

Answer 7

TCV fails to full cooling flow (ALL FLOW THROUGH COOLER

Question 8

How does the SWC PCV fail on loss of IA?

Answer 8

Fails open on loss of IA

Question 9

How does SWC connect to Generator Stators?

Answer 9

Inlet and outlet headers both enter top of generator to ensure internal stator bars kept full on loss of pumps.
Anti siphon bypass line and vent prevetns stator from siphoning off when cooling pumps not running

Question 10

What is the normal flow through SWC Deionizer?

Answer 10

75gprm

Question 11

What is normal flow through Alterrex Field Rectifiers?

Answer 11

20GPM

Question 12

How does the Stator Cooling Water Pump Auto Start Test Button work?

Answer 12

Local button used to test auto start feature of standby pump WITHOUT tripping running pump

Question 13

What interlocks exist for SWC Pumps?

Answer 13

If running pump discharge pressure drops to 65psig, standby pump auto starts (backup pressure switch at 60psig)

Both SWC pumps trip on main generator lockout

Question 14

What is the Stator Water Cooling Runback?

Answer 14

If >25% stator current, cooling is required.
On loss of stator cooling, turbine load set on DEHC is set to automatically runback w/in 2 minutes to 25% of max. generator/turbine load
Turbine trips if amps >27395 in 2 min, OR >9121 after 3.5 min

Signal received:
Lo Gen. Inlet water pressure >4 seconds (33psig)
Gen Hi outlet water temp (80C)

Question 15

What are teh SWC Runback setpoints?

Answer 15

30# Gen Inlet water
500gpm Lo Gen inlet water flow
80C Gen Hi Outlet water Temp

3+5=8

Question 16

On a loss of SWC what are the limits for conductivity?

Answer 16

<0.5uS/cm2 - Restor cooling water w/in 1 hour
>0.5 & <1.0 - Trip Turbine in 3 minutes
> 1.0 - Trip immediately

Question 17

On a SWC RUNBACK, what is the allowable RTP before a SCRAM will occur?

Answer 17

~60% - ~35% BP Flow and 25% Turbine