Compressed Air Flashcards
What are the PAC trips?
- Loadshed (T11/21B)
- Load Conservation (Train B)
- Motor Overload
- Lo Lube Oil Press
- Hi Lube Oil Temp
- Hi 1st & 2nd Interstage Temp
- PAC Motor Lo Current
- PAC DCCS loss of control power
- Loss of most transmitters
- Manual (Several Inputs)
When will the PAC Aux Lube Oil Pump start?
- On PAC start - remains running until > 42 psig.
- PAC is stopped (for 15 minutes)
- low lube oil press
- loss of DCCS control power
- PA header - 97# with PAC in AUTO
What are the CAC trips?
- Overload
- LO # Low (15# with 12 sec delay)
- NESW # Low (< 6# for 5 sec) (U1) (includes on start)
- NESW # Low (< 4.2 ΔP for 10 sec) (U2) (includes on start)
- Manual
Does the CAC trip on a Load Shed?
No
What are the BACPAC trips?
- Motor Overload
- LO Press low
- LO Temp High
- 1st & 2nd Stage Disch Temp high
- 2nd Stage Suction Temp hi
- Manual
What are the Compressed Air System header pressure actions?
- 97 psi = PAC Start
- 90 psi = CAC Start (WAR #)
- 85 psi = PA Hdr Isolations Close
- 80 psi = Manual Reactor Trip
What is the correct sequence of events that automatically occur in the Control and Plant Air Systems as air pressure lowers?
- 97 psig at PPS-10 (20) Standby PAC starts
- 90 psig CAS wet receiver pressure CAC starts
- 85 psig at PPS-11 (21) Plant air header isolates
What can cause PAC surge?
- Discharge Valve Closed/Blocked
- Inlet Valve Throttled too far Closed
- Insufficient Inter-stage Cooling
- Opening demister valves too quickly
- Hi System Press
What is a Surge of the PAC?
Performance characteristic of a centrifugal compressor that arises when the compressor can’t overcome the system resistance
Seal air pressurizes the PAC seals when ?
- Standby
- Start-up
- Unloaded
When loaded, the PAC seals are pressurized from?
Leakage from itself
What problem does a loss of PAC seal air cause?
May allow oil leakage from the drive casing into the compressor housing
Where does the BACPAC tie into the Air System at and why is this important?
To the Plant Air ring header between the Ring Header Isolations (ie can supply CA system directly with Plant Air Ring Header isolation valves closed)
Both Units are responding to a loss of Plant and Control Air event.
The following conditions exist: Both Unit’s PACs AND CACs have failed.
Both Unit’s PA Hdr pressures are 70 psig and lowering. Both Unit’s CA Hdr pressures are 82 psig and lowering.
An AEO has been dispatched to start the Back-up Plant Air Compressor (B/U PAC), per 01-OHP-4022-064-001, Control Air Malfunction.
What describes the B/U PAC ability to repressurize both Unit’s Control Air Systems under these conditions?
The B/U PAC will discharge to both Unit’s Control Air Systems
How does Suction Throttle Control work?
Throttles inlet valve prior to throttling the unloader valve in order to maintain discharge pressure and minimum current setpoint.