MT Ctrls

Question 1

What is IOPS powered by?

Answer 1

• 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 will a 10% manual runback give you?

Answer 6

• 114.9 MW (121.7)** < 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 are the parameters that a loss of a MFP runback give you?

Answer 8

Main Turbine > 60% Load

• Goes to 625 (725) 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 will a 20% manual runback give you?

Answer 9

• 229.8 MW (243.4) < actual load
• Lower Target Load by 100 MW/min
• Forced to MW In

Question 10

What parameters will a OPΔT and OTΔT (Rx) Runback give you?

Answer 10

• Target Load to 30 MW *** @ 124 (144) MW/min
• Speed x10 for the first sec to equal the 124/144 MW/min) (1 sec, then waits 9.5 sec until 1st stage # is < 40%)
• 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 does a power load unbalance signal do when it acutates?

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

• CRID 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
• Signal clears when MT impulse pressure is < 40%

Question 22

What is the purpose of Power Load Unbalance?

Answer 22

• Provides overspeed protection in the event of a large load rejection
• Used only on ATWS when the MT also fails to trip with manual AMSAC or Solenoid Trip

Question 23

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

Answer 23

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

Question 24

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

Answer 24

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