3B2 ABSA UPDATED ACTUAL Questions
and CORRECT Answers
A dummy piston is used on a steam turbine to: - CORRECT ANSWER - Counter end
thrust
The entrance angle of a reaction blade is: - CORRECT ANSWER - Almost 90 degrees
To ensure a tight seal, a steam turbine balance piston is fitted with _____. - CORRECT
ANSWER - Labyrinth seals
Extraction turbines are turbines where steam is extracted at one or more points at constant: -
CORRECT ANSWER - Pressure
In a steam turbine having pressure drop across the moving blades, an unbalanced _____ thrust
will be developed upon the rotor. - CORRECT ANSWER - Axial
All large disc rotors are machined from __________ steel: - CORRECT ANSWER -A
solid forging of nickel steel.
Convergent-divergent nozzles are used when: - CORRECT ANSWER - 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: - CORRECT ANSWER - Maximum blade clearance
In a steam turbine using velocity compounding _____ expand(s) the steam from initial to exhaust
pressure. - CORRECT ANSWER - One set of nozzles
A thrust adjusting gear: - CORRECT ANSWER - 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? - CORRECT ANSWER - Shrink fitted and
welded
Steam turbine casing joints are made steam tight by matching _____ exactly. - CORRECT
ANSWER - 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: - CORRECT ANSWER - Topping turbine
A reaction turbine has: - CORRECT ANSWER - 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: - CORRECT ANSWER - Thermal stress in the shaft
The purpose of compounding in a steam turbine is to: - CORRECT ANSWER - Reduce
steam and blade velocity
On larger turbines the _____ is split in a horizontal direction. - CORRECT ANSWER -
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. - CORRECT ANSWER - 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? - CORRECT ANSWER - 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: - CORRECT ANSWER - Decrease
A water seal is used on some steam turbines ________ to insure that no air leaks in along the
shaft: - CORRECT ANSWER - 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 ___________. - CORRECT
ANSWER - Bend upwards
The warm-up time required of a turbine is dependant on: - CORRECT ANSWER - The
size of the turbine
The advantage of mechanical-hydraulic governors is: - CORRECT ANSWER -
Mechanical losses are greatly reduced
In order to supply oil at two different pressures, a typical turbine lube oil system has: -
CORRECT ANSWER - A pressure reducing valve
Overspeed trips: - CORRECT ANSWER - Are independent of the governing system
In a back-pressure turbine the governor is _____ sensitive. - CORRECT ANSWER -
Pressure
On startup of a large condensing turbine, the cooling water to the oil cooler is turned on: -
CORRECT ANSWER - When the oil reaches normal operating temperatures
In an overspeed trip the spring loaded tripping bolt has a center of gravity: - CORRECT
ANSWER - Towards the head end of the bolt
, Turbines used to drive auxiliary equipment are usually lubricated by: - CORRECT
ANSWER - Ring-oiled bearings
A mechanical overspeed trip is designed to _____ in the event of an overspeed condition. -
CORRECT ANSWER - Shut off the turbine's steam supply
When starting an extraction turbine, sealing steam to the turbine glands is admitted _____ is put
in operation - CORRECT ANSWER - After the extraction pump
The barring gear: - CORRECT ANSWER - 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 - CORRECT
ANSWER - After the extraction pump
In a turbine circuit, feed heaters and deaerators serve to: - CORRECT ANSWER -
Increase efficiency
A simple mechanical governor uses a _____ attached to the end of the turbine shaft. -
CORRECT ANSWER - Set of weights
The overspeed trip a turbine is usually set to trip the mechanism when it reaches _____ of
operating speed. - CORRECT ANSWER - 110%
In an/a _____, the spring loaded tripping bolt has a center of gravity slightly off the center of the
shaft. - CORRECT ANSWER - Overspeed trip
_____ is the percentage change in speed of a steam turbine from no load to full load conditions. -
CORRECT ANSWER - Governor speed droop
and CORRECT Answers
A dummy piston is used on a steam turbine to: - CORRECT ANSWER - Counter end
thrust
The entrance angle of a reaction blade is: - CORRECT ANSWER - Almost 90 degrees
To ensure a tight seal, a steam turbine balance piston is fitted with _____. - CORRECT
ANSWER - Labyrinth seals
Extraction turbines are turbines where steam is extracted at one or more points at constant: -
CORRECT ANSWER - Pressure
In a steam turbine having pressure drop across the moving blades, an unbalanced _____ thrust
will be developed upon the rotor. - CORRECT ANSWER - Axial
All large disc rotors are machined from __________ steel: - CORRECT ANSWER -A
solid forging of nickel steel.
Convergent-divergent nozzles are used when: - CORRECT ANSWER - 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: - CORRECT ANSWER - Maximum blade clearance
In a steam turbine using velocity compounding _____ expand(s) the steam from initial to exhaust
pressure. - CORRECT ANSWER - One set of nozzles
A thrust adjusting gear: - CORRECT ANSWER - 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? - CORRECT ANSWER - Shrink fitted and
welded
Steam turbine casing joints are made steam tight by matching _____ exactly. - CORRECT
ANSWER - 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: - CORRECT ANSWER - Topping turbine
A reaction turbine has: - CORRECT ANSWER - 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: - CORRECT ANSWER - Thermal stress in the shaft
The purpose of compounding in a steam turbine is to: - CORRECT ANSWER - Reduce
steam and blade velocity
On larger turbines the _____ is split in a horizontal direction. - CORRECT ANSWER -
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. - CORRECT ANSWER - 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? - CORRECT ANSWER - 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: - CORRECT ANSWER - Decrease
A water seal is used on some steam turbines ________ to insure that no air leaks in along the
shaft: - CORRECT ANSWER - 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 ___________. - CORRECT
ANSWER - Bend upwards
The warm-up time required of a turbine is dependant on: - CORRECT ANSWER - The
size of the turbine
The advantage of mechanical-hydraulic governors is: - CORRECT ANSWER -
Mechanical losses are greatly reduced
In order to supply oil at two different pressures, a typical turbine lube oil system has: -
CORRECT ANSWER - A pressure reducing valve
Overspeed trips: - CORRECT ANSWER - Are independent of the governing system
In a back-pressure turbine the governor is _____ sensitive. - CORRECT ANSWER -
Pressure
On startup of a large condensing turbine, the cooling water to the oil cooler is turned on: -
CORRECT ANSWER - When the oil reaches normal operating temperatures
In an overspeed trip the spring loaded tripping bolt has a center of gravity: - CORRECT
ANSWER - Towards the head end of the bolt
, Turbines used to drive auxiliary equipment are usually lubricated by: - CORRECT
ANSWER - Ring-oiled bearings
A mechanical overspeed trip is designed to _____ in the event of an overspeed condition. -
CORRECT ANSWER - Shut off the turbine's steam supply
When starting an extraction turbine, sealing steam to the turbine glands is admitted _____ is put
in operation - CORRECT ANSWER - After the extraction pump
The barring gear: - CORRECT ANSWER - 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 - CORRECT
ANSWER - After the extraction pump
In a turbine circuit, feed heaters and deaerators serve to: - CORRECT ANSWER -
Increase efficiency
A simple mechanical governor uses a _____ attached to the end of the turbine shaft. -
CORRECT ANSWER - Set of weights
The overspeed trip a turbine is usually set to trip the mechanism when it reaches _____ of
operating speed. - CORRECT ANSWER - 110%
In an/a _____, the spring loaded tripping bolt has a center of gravity slightly off the center of the
shaft. - CORRECT ANSWER - Overspeed trip
_____ is the percentage change in speed of a steam turbine from no load to full load conditions. -
CORRECT ANSWER - Governor speed droop
