MT Ctrls

Question 1

What is IOPS powered by?

Answer 1

• U1 CCRP, DCSD-B, DCSD-C

- U2 CRIDS I, II, III

Question 2

What does IOPS do?

Answer 2

• Backup to DCS overspeed trip via 3 passive magnetic pickup probes (2/3)
• 110% Overspeed Trip ** (Hardwire trip)
• Its energize to trip (2/3) ***

Question 3

What is the DCS power supply?

Answer 3

• BOP Battery (250 VDC) thru inverter **

- BLC/CLC backup to inverters **

Question 4

What is the DCS purpose?

Answer 4

• Supply hydraulic fluid for stop/control valve operation during normal and emergency conditions. ***

Question 5

What does hood spray protect?

Answer 5

• Prevents LPT blade overheating ***

Question 6

What parameters (MW target, Rate, and MWin/MWout) will a 10% manual runback give you?

Answer 6

• 114.9 MW (125.4)** < actual load
• Lower Target Load by 100 MW/min
• Forced to MW In

Question 7

When is a loss of a MFP runback enabled?

Answer 7

• > 60%

Question 8

What parameters (MW target, Rate, and MWin/MWout) does a loss of a MFP runback give you?

Answer 8

Main Turbine > 60% Load

• Goes to 625 (752.4) MW
• U1 goes @ 600 MW/min
• U2 goes @ 1000MW/min when > 90% Pwr and 140MW/ min at < 90%
• Forced to MW In

Question 9

What parameters (MW target, Rate, and MWin/MWout) will a 20% manual runback give you?

Answer 9

• 229.8 MW (250.8) < actual load
• Lower Target Load by 100 MW/min
• Forced to MW In

Question 10

What parameters (MW target, Rate, and MWin/MWout) will a OPΔT and OTΔT (Rx) Runback give you?

Answer 10

• Target Load to 30 MW *** @ average of 137 (149) MW/min
• Speed x10 for the first sec to equal the 137/149 MW/min) (1 sec, then waits 9.5 sec to see if condition has cleared)
• Forced to MW In

Question 11

When is power load unbalance armed?

Answer 11

• Armed when 1st Stage Press > 40% (from DCS) ***

Question 12

When is power load unbalance actuated?

Answer 12

• Actuated if difference between turbine and generator current is > 40% AND rate of change in current is > 13k amps /sec.

Question 13

What parameters (MW target, Rate, and MWin/MWout) does a power load unbalance signal give you?

Answer 13

• Load Ref to 30 MW @ 1389 Mw/min. (MW-Out)
• Fast close solenoids for control and intercept valves actuate
• Forced to MW Out

Question 14

What does the Droop Speed override signal do?

Answer 14

• Protects Turbine from overspeed condition with output breaker closed
• Biases Load Ref signal which closes down on control valves and Intermediate Valves

Question 15

When is the Droop Speed override signal active?

Answer 15

• > 1805 rpm

Question 16

What is the primary tripping device of the Main Turbine?

Answer 16

• Trip Block Assembly

Question 17

How do the trip block assemblies work?

Answer 17

• De-energize to trip on 2/3 solenoids which drain back to EHC tank***
• One Trip block trip will close all 20 valves

Question 18

What are the trip block assemblies powered by?

Answer 18

• U1 CCRP, DCSD-B, DCSD-C

- U2 CRIDS I, II, III

Question 19

What is the one turbine trip input from TSI?

Answer 19

• Thrust Bearing Wear ***

Question 20

Will a failure of all 3 PLC speed sensors on the Turbine give you a turbine trip while on the grid?

Answer 20

• No, it will not ***

Question 21

What does an ATWS runback do?

Answer 21

• Target Load to 1 MW at 1389 MW/min.

- Forced to MW In

Question 22

When you are starting up the Turbine when do the Reheat Valves open?

Answer 22

• The Reheat Valves open when the Turbine is “Reset”

Question 23

What do the combined stop and intercept valves do for the turbine?

Answer 23

• protect against overspeed of the turbine from residual steam from the MSRs on a turbine trip ***

Question 24

What is the difference between MW in and MW out

Answer 24

• MW in = Valves will move to maintain MW

- MW out = Valves will not move from pre-determined reference point