What is the auto transfer logic for the Startup transformers?
- Transformer available (no SU 1 LO, no undervoltage, not in PTL)
- No A-1 or applicable bus Lockout
- Transformer selected or other transformer not available
- Gen LO and SU2 breaker open or SU2 LO and unit aux bkr open
- In sync (fast transfer) or UV (slow transfer)
What are the power sources for switch yard control power?
- Normal: 22kv off tertiary winding through 480v xfmr
- Auto Xfer: B-3
- Man xfer: B-6
What is the purpose of dynamic disturbance recording panel (C002)?
Monitor and record potential grid disturbances. (Provides no control functions)
What will cause a startup 1 transformer lockout?
1) phase volt differential
2) neutral over current
3) sudden gas pressure
4) Volt reg LO
5) Auto xfmr LO
What are the power sources for RCPs?
H-1: A & C
H-2: B & D
What provides DC control power to H bus feeder breakers? Load breakers?
Feeder: D-46
Loads: D-11/21
What functions do the DC control breakers in breaker cubicle provide?
Control power and protective relay functions
What causes a SU2 load shed and what occurs?
A-1 OR A-2 tie on
H-1 & H-2 tie on
Trips: - RCPs (Trips A & D)
- Cond pumps (A C B)
- Htr drain pumps (Both)
- CW Pumps (B D A C)
- Main chillers (Both)
What is the effect of a Lockout and Undervoltage condition on a bus?
- LO causes feeder breakers to open and prevents close of them
- UV causes load breakers to open
What is the logic to manually close A-309/A-409?
- No A-1/A-3 LO
- Sync switch on
- Sync check closed
- HS Closed
(If A-3 dead, must hold close until UV clears)
What causes A-309/A-409 breakers to trip?
- A-1 or A-3 LO
- Phase directional OC (Protect diesel with A-1 closed and EDG output bkr closed)
- Phase directional Ground
- A-3/A-4 or B-5/B-6 UV
What will cause EDG output breakers (A-308/A-408) to auto close?
- No UV on EDG
- breaker not in PTL
- No A-3 LO
- A-310/410 and A-309/409 open
A-3/A-4 UV (2 seconds < 2450 V)
B-5/B-6 UV (8 seconds < 429 V)
What will cause EDG output breakers to trip?
- Loss voltage regulator
- EDG LO
- A-3 LO
- A-308 closed, GEN LO, and UA feeder closed (protects the diesel)
What causes A-3/A-4 cross-tie breakers (A-310/410) to trip?
- ES
- A-3 LO or UV
- Overcurrent
- If A-3/A-4 powered from A-1/2 or EDG and opposite cross-tie breaker closed (3 of 4 breakrs closed)
What is the voltage band for B-5/B-6 and what are effects on equipment when operating outside of these limits?
460-500 Volts
Low Voltage - increase in amperage resulting in overheating of motors
High Voltage - results in magnetic portions of motors into saturation and possible overheating
Why do we have a B-5/B-6 undervoltage bypass and how long is the time delay associated with it?
- The bypass is used to starting RCPs due to large amount of starting current and lowering of 480V bus voltage.
- The time delay is 20 seconds.
What is the low voltage alarm for D-01/D-02?
< 105 Volts
What are the D-01/D-02 ground alarms and what actions are required when these values are met?
- Voltage on either meter 20 - 50 V -> Initiate CR
- Voltage on either meter < 20 V -> CR, contact engineer, bridge call and callout maintenance
What are the power supplies for the battery chargers?
D03A - B-51
D03B - B-57
D04A - B-61
D04B - B-65
What is the purpose of the 120V AC electrical distribution system?
Provides an uninterrupted 120 V AC to important systems and indications (RPS, ESAS, EFIC, etc)
What causes vital inverter to swap over to AC source?
- Output voltage low
- Output current Hi
- Inverter failure
- Low DC Input (Y-41 only)
Which inverter supplies C540?
- Y-22 or Y-25
How is the autotransformer constructed and what does it supply?
-The autotransformer consists of 3 windings. The primary winding is 500 KV, the secondary winding supplies 161 KV Ring bus to SU2, and the 3rd 22 KV tertiary winding supplies SU1 and SU3 provides DC control power to the switchyard.
What does the term “breaker and a half” mean?
- This term refers to the use of 3 breakers to supply 2 loads. One breaker is shared between the 2 instead of 2 seperate breakers for isolation.
