3B2 ABSA Questions and Answers (100%
Correct Answers) Already Graded A+
A dummy piston is used on a steam turbine to: [ Ans: ]
Counter end thrust
The entrance angle of a reaction blade is: [ Ans: ] Almost
90 degrees
To ensure a tight seal, a steam turbine balance piston is
fitted with _____. [ Ans: ] Labyrinth seals
Extraction turbines are turbines where steam is extracted
at one or more points at constant: [ Ans: ] Pressure
In a steam turbine having pressure drop across the
moving blades, an unbalanced _____ thrust will be
developed upon the rotor. [ Ans: ] Axial
All large disc rotors are machined from __________ steel: [
Ans: ] A solid forging of nickel steel.
Convergent-divergent nozzles are used when: [ Ans: ] High
pressure drops are required
During start up of a steam turbine the thrust block is
pushed against a stop in the direction of the exhaust for: [
Ans: ] Maximum blade clearance
,In a steam turbine using velocity compounding _____
expand(s) the steam from initial to exhaust pressure. [
Ans: ] One set of nozzles
A thrust adjusting gear: [ Ans: ] Positions the turbine rotor
axially
A hollow drum rotor of a steam turbine is machined both
outside and inside. How is the drum end cover with shaft
installed in the rotor? [ Ans: ] Shrink fitted and welded
Steam turbine casing joints are made steam tight by
matching _____ exactly. [ Ans: ] Flange faces
A back-pressure turbine with exhaust steam going to an
old boiler header that is supplying steam to an old lower
pressure turbine is called a: [ Ans: ] Topping turbine
A reaction turbine has: [ Ans: ] Rows of stationary blades
alternating with rows of moving blades
When disc rotors are assembled, the discs are heated until
they are easily slid along the shaft and then located in the
correct position on the shaft and shaft key. A small
clearance between the discs prevents: [ Ans: ] Thermal
stress in the shaft
The purpose of compounding in a steam turbine is to: [
Ans: ] Reduce steam and blade velocity
On larger turbines the _____ is split in a horizontal
direction. [ Ans: ] Cylinder
,The pressure at the outlet from the moving blades is the
same as the pressure at the inlet to the moving blades in
a/an __________ turbine. [ Ans: ] Impulse
In a condensing-bleeder turbine up to 2% of the total
steam flow may be bled off. What is the bleed-steam used
for? [ Ans: ] Feed-water heating
It is general practice to let the thickness of the walls and
flanges _____ from inlet to exhaust end of a steam turbine
casing: [ Ans: ] Decrease
A water seal is used on some steam turbines ________ to
insure that no air leaks in along the shaft: [ Ans: ] At
speeds above 2000 rev/mm
If a turbine is shut down and left at a standstill while still
hot, the lower half of the rotor will cool faster than the
upper half. The rotor will "hog", which means it will
___________. [ Ans: ] Bend upwards
The warm-up time required of a turbine is dependant on: [
Ans: ] The size of the turbine
The advantage of mechanical-hydraulic governors is: [
Ans: ] Mechanical losses are greatly reduced
In order to supply oil at two different pressures, a typical
turbine lube oil system has: [ Ans: ] A pressure reducing
valve
, Overspeed trips: [ Ans: ] Are independent of the governing
system
In a back-pressure turbine the governor is _____ sensitive.
[ Ans: ] Pressure
On startup of a large condensing turbine, the cooling
water to the oil cooler is turned on: [ Ans: ] When the oil
reaches normal operating temperatures
In an overspeed trip the spring loaded tripping bolt has a
center of gravity: [ Ans: ] Towards the head end of the bolt
Turbines used to drive auxiliary equipment are usually
lubricated by: [ Ans: ] Ring-oiled bearings
A mechanical overspeed trip is designed to _____ in the
event of an overspeed condition. [ Ans: ] Shut off the
turbine's steam supply
When starting an extraction turbine, sealing steam to the
turbine glands is admitted _____ is put in operation [ Ans:
] After the extraction pump
The barring gear: [ Ans: ] Should disengage and
automatically shut down after steam starts to rotate the
turbine
Sealing steam to the turbine glands is admitted _____ is
put in operation [ Ans: ] After the extraction pump
Correct Answers) Already Graded A+
A dummy piston is used on a steam turbine to: [ Ans: ]
Counter end thrust
The entrance angle of a reaction blade is: [ Ans: ] Almost
90 degrees
To ensure a tight seal, a steam turbine balance piston is
fitted with _____. [ Ans: ] Labyrinth seals
Extraction turbines are turbines where steam is extracted
at one or more points at constant: [ Ans: ] Pressure
In a steam turbine having pressure drop across the
moving blades, an unbalanced _____ thrust will be
developed upon the rotor. [ Ans: ] Axial
All large disc rotors are machined from __________ steel: [
Ans: ] A solid forging of nickel steel.
Convergent-divergent nozzles are used when: [ Ans: ] High
pressure drops are required
During start up of a steam turbine the thrust block is
pushed against a stop in the direction of the exhaust for: [
Ans: ] Maximum blade clearance
,In a steam turbine using velocity compounding _____
expand(s) the steam from initial to exhaust pressure. [
Ans: ] One set of nozzles
A thrust adjusting gear: [ Ans: ] Positions the turbine rotor
axially
A hollow drum rotor of a steam turbine is machined both
outside and inside. How is the drum end cover with shaft
installed in the rotor? [ Ans: ] Shrink fitted and welded
Steam turbine casing joints are made steam tight by
matching _____ exactly. [ Ans: ] Flange faces
A back-pressure turbine with exhaust steam going to an
old boiler header that is supplying steam to an old lower
pressure turbine is called a: [ Ans: ] Topping turbine
A reaction turbine has: [ Ans: ] Rows of stationary blades
alternating with rows of moving blades
When disc rotors are assembled, the discs are heated until
they are easily slid along the shaft and then located in the
correct position on the shaft and shaft key. A small
clearance between the discs prevents: [ Ans: ] Thermal
stress in the shaft
The purpose of compounding in a steam turbine is to: [
Ans: ] Reduce steam and blade velocity
On larger turbines the _____ is split in a horizontal
direction. [ Ans: ] Cylinder
,The pressure at the outlet from the moving blades is the
same as the pressure at the inlet to the moving blades in
a/an __________ turbine. [ Ans: ] Impulse
In a condensing-bleeder turbine up to 2% of the total
steam flow may be bled off. What is the bleed-steam used
for? [ Ans: ] Feed-water heating
It is general practice to let the thickness of the walls and
flanges _____ from inlet to exhaust end of a steam turbine
casing: [ Ans: ] Decrease
A water seal is used on some steam turbines ________ to
insure that no air leaks in along the shaft: [ Ans: ] At
speeds above 2000 rev/mm
If a turbine is shut down and left at a standstill while still
hot, the lower half of the rotor will cool faster than the
upper half. The rotor will "hog", which means it will
___________. [ Ans: ] Bend upwards
The warm-up time required of a turbine is dependant on: [
Ans: ] The size of the turbine
The advantage of mechanical-hydraulic governors is: [
Ans: ] Mechanical losses are greatly reduced
In order to supply oil at two different pressures, a typical
turbine lube oil system has: [ Ans: ] A pressure reducing
valve
, Overspeed trips: [ Ans: ] Are independent of the governing
system
In a back-pressure turbine the governor is _____ sensitive.
[ Ans: ] Pressure
On startup of a large condensing turbine, the cooling
water to the oil cooler is turned on: [ Ans: ] When the oil
reaches normal operating temperatures
In an overspeed trip the spring loaded tripping bolt has a
center of gravity: [ Ans: ] Towards the head end of the bolt
Turbines used to drive auxiliary equipment are usually
lubricated by: [ Ans: ] Ring-oiled bearings
A mechanical overspeed trip is designed to _____ in the
event of an overspeed condition. [ Ans: ] Shut off the
turbine's steam supply
When starting an extraction turbine, sealing steam to the
turbine glands is admitted _____ is put in operation [ Ans:
] After the extraction pump
The barring gear: [ Ans: ] Should disengage and
automatically shut down after steam starts to rotate the
turbine
Sealing steam to the turbine glands is admitted _____ is
put in operation [ Ans: ] After the extraction pump
