Instrument and Service Air Systems

Question 1

Purpose of Instrument AIr? (IA)
How many Compressors? At what psi?
Can be used for?

Answer 1

• provide dry, oil-free, compressed air for components and instruments.
• 5 compressors supply air at 100psig
• Capable of being used for breathing air

Question 2

Purpose of Station Air? (SA)

Answer 2

• provide compressed air for general plant use and for maintenance use
• 1 compressor supplies air at 100psig
• Not used for breathing air

Question 3

Instrument Air Compressors A/B

Location? Power supply? Cooled by? Trips?

Answer 3

• 1st Floor Aux hallway
• A, MCC-5
• B, MCC-6
• SW supplies water jackets and aftercoolers. (SW is auto secured when compressor is not running)
• Backup to the PAC or “D” IAC Compressors.
• Low lube oil with 10 sec delay and high air discharge temp (470F)

Question 4

IA Dryers A/B

Location, power supply

Answer 4

• Maintain air dew point of minus 10F
• Located beside A/B IA compressors
• A- MCC-9
• B- MCC-10

Question 5

IA “D” compressor

Location? Power Supply? Runs when? Cooled by?

Answer 5

• Located NW in the power block
• MCC-13 (along with its dryer)
• Run time is alternated with the PAC
• AIr Cooled Unit

Question 6

PAC

Location? Power Supply?

Answer 6

• East of IA “D”
• MCC-17 (along with its dryer)
• Air Cooled Unit

Question 7

Station Air Compressor

Location? Power supply? Cooled by?

Answer 7

• 1st Floor Aux Building Hallway
• 480V Bus 2B
• Water jacket and aftercooler uses Service Water. Auto secures when not in use.

Question 8

Why Do we Secure SW to the SA and IA “A/B” when not in use?

Answer 8

-To prevent condensation build up in the cylinders

Question 9

IAC “F”

Purpose? Location? Power Supply?

Answer 9

• supply air for the operation of the intake screen bubbler system and support operation of the SW strainers.
• South of Intake Structure
• LP-49 (located in Security Building)
• Not capable of producing air of breathing quality.

Question 10

Set points for compressors in Auto

Answer 10

• IAC A/B 90-105psi

- SAC 95-105psi

Question 11

Set Points for compressors in Manual?

Answer 11

• IAC A/B 98-102psi
• IAC D 97-104psi
• PAC 100-104psi
• SAC 98-102psi

Question 12

Why does the IAC “A/B” breaker trip when power is lost to their MCCs?

Answer 12

-To protect the EDG from a possible overload. ECCS equipment will sequence on but IAC’s are not analyzed as part of the ECCS equipment and an operator will have to go close the breakers after a SI or LOOP