Generator gas

Question 1

Purpose

Answer 1

Purpose
Primary - Pressurize and cool the generator with H2 to increase maximum practical output rating.

Secondary - Provide a means to safely add and remove H2 to preclude combustion.

Question 2

Advantages of using H2

Answer 2

High thermal conductivity and heat transfer coefficient increases heat removal.
Low density reduces heating due to windage.
Eliminates presence of oxygen to prevent insulation oxidation and moisture induced arcing.
Eliminates presence of oxygen to prevent fires.

Question 3

Disadvantages of H2

Answer 3

It is explosive when combined with the correct concentration of oxygen. (4% to 75%).
Must be purged with CO2 prior to entering the generator.
H2 leaks easily so make-up required.

Question 4

Generator hydrogen cooled by….

Answer 4

….WS

Question 5

float switches on bottom of generator

Answer 5

4 float switches mounted at the bottom of the generator housing.

Detect liquid and alarm at _PL01J.

Question 6

Hydrogen Pressure band

Answer 6

65-80psig

Question 7

What purges CO2 from generator?

Answer 7

Instrument Air

Question 8

Generator condition monitor filter function

Answer 8

Filter/Solenoid
Used to verify an actual alarming condition or malfunctioning condition monitor.
Depress filter button (local or remote) removes particles.
Ion chamber output current should increase to normal.
Failure to return to a normal reading indicates a malfunctioning monitor.

Question 9

Hydrogen purity alarm setpoints

Answer 9

Lo lo 90%

Lo 95%

Question 10

Upper limit of hydrogen curve MVAR out/High MW
middle limit of hydrogen curve No MVAR/High MW
Lower limit of hydrogen curve MVAR in/High MW

Answer 10

U= Rotor winding temp
M=Stator winding temp
L=Stator core temp

Question 11

Generator condition monitor trouble alarms on ……

Answer 11

PM02J in MCR

Question 12

hydrogen range for combustion/explosion

Answer 12

4-75% by volume of hydrogen