Main Power - .5

Question 1

What do AX501 and BX501 supply?

Answer 1

1E 4160VAC Busses

Question 2

What do AX502 and BX502 supply?

Answer 2

7.2KV busses.

Question 3

What do AX503 and BX503 supply?

Answer 3

Circ. Water.

Question 4

Generator Lockout Signals w/ output bkr closed.

Answer 4

1. Gen loss of field* (reg. and b/u)
2. Gen out of step* (R&B)
3. Gen field overvoltage (10 sec TD) ( Reg)
4. Gen field overexcitation (Reg)

Question 5

Generator lockout signals.

Answer 5

1. Alterex Exciter Diff O/C *(Reg)
2. Gen (Phase) Diff O/C* (Reg)
3. Gen O/C (b/u)
4. Gen Neg Phase Sequence (Reg)
5. Gen Reverse Power:
   Reg.-2.5 sec w/ turbine trip
   B/U-30 sec w/o turbine trip
   * Also trips stator water cooling pumps on Gen Diff O/C

Question 6

Generator Lockout Auto Actions
(Also trips stator water cooling pumps on gen diff o/c)

Answer 6

1. Trip Gen Output Breaker (2-6 and 6-5)
2. Trip Exciter Field Breaker
3. Trips the Turbine
4. Initiates Breaker Failure Protection (2-6 and 6-5)
5. Overhead Alarms and Process Computer Alarms

Question 7

Unit Lockout Signals

Answer 7

1. Unit Diff O/C (Regular & Backup)
2. Gen Neutral O/C (Regular & Backup)
3. Gen Neutral O/V (Backup Only – Shutdown Protection)*

*Both output breakers must be OPEN to activate.

Question 8

Unit Lockout Auto Actions

Answer 8

-Main Transformer Cooling Fans Trip
-Stator Water Cooling Pumps Trip
-Trip Gen Output Breaker (2-6 and 6-5)
-Trip Exciter Field Breaker
-Trips the Turbine
-Initiates Breaker Failure Protection (2-6 and 6-5)
-Overhead Alarms and Process Computer Alarms

Question 9

Load Break Disconnects indicator colors.

Answer 9

1. Gas Pressure Indicator – Gray (normal), Red (low pressure)
2. Interrupting Unit Targets – Gray (normal), Yellow (open)

Question 10

What is BKR fan out?

Answer 10

If a BKR is suppose to open but fails to, the next BKR in line will open.

Question 11

Disconnect and ground interlock.

Answer 11

Both cannot be closed at the same time.

Question 12

SLP 3 & SLP 4 function

Answer 12

Supplies power to to the site ring bus.

Question 13

Normal 13.8KV disconnect and BKR lineup.

Answer 13

1. All disconnects are normally closed except for 13T30 and 24T30.
2. All BKRs are normally closed except for 2-3 and 7-8.

Question 14

13.8KV disconnect interlocks.

Answer 14

1T30, 3T30, and 13T30 (2T30, 4T30, and 24T30) are key interlocked such that only 2 can be closed at one time.

Question 15

What causes a station power transformer lockout?

Answer 15

Differential overcurrent.

Question 16

13.8KV BKR interlocks.

Answer 16

1. 2-3 (7-8) breakers cannot be closed unless either 1-2 OR 4-5 (6-7 OR 9-0) breaker is open.
2. The breaker that was opened can be reclosed once the 2-3 (7-8) breaker is closed.

Question 17

500KV 1-5 and 1-3 feature .

Answer 17

1-5 and 1-3 breakers have an auto re-close feature.

Question 18

Main transformer cooling.

Answer 18

There are 3 groups of fans with 1 normally running. 2 and 3 run based on high oil temp.

Question 19

Isophase H2 monitors.

Answer 19

Alarm if H2 exceeds 4% but fails downscale in this condition.

Question 20

Tap changer operation.

Answer 20

Do not operate when energized, it has a potential for personnel injury.

Question 21

Main turbine turning gear requirements.

Answer 21

MG output breakers (2-6 and 6-5) open, or
MG disconnect (52x60) open.

Question 22

What does the breaker emergency trip handle do?

Answer 22

Removes control power.

Question 23

How can you remove control power from a (a) 500KV breakers and (b)Load Break Disconnects and (c)13.8 KV breakers?

Answer 23

(a) Control power can be removed by operating the toggle switch located on the emergency trip handle
(b) Control power can be removed by opening the toggle switch on the inside of the enclosure
(c) A toggle switch(interlocked with the emergency trip handle) removes DC control power to the breaker