Power Engineering 3A2 (ABSA Power Engineering 3A2)
Questions With Complete Solutions
________ valve bodies in general can be used on water service
up to temperatures of about 250°C. Correct Answers Cast-iron
__________ are used to convert physical quantities of flow,
level, temperature, pressure, and weight into electrical signals
that represent those quantities as accurately as possible. Correct
Answers Transmitters
A 3-ohm resistor has a power rating of 1.5 watts. The maximum
loading is ______________. Correct Answers 0.707 amps
A boiler drum is made of SA-515-70 steel and has a ligament
efficiency of 0.66. If the steam temperature is 280°C and the
inside diameter of the drum is 1.6 m and the thickness of the
drum is 68.45 mm. What will the maximum operating pressure
be, in kPa? Correct Answers 6500 kPa
A circuit breaker is an automatic device that
______________________. Correct Answers indicates circuit
status.
opens under abnormally high current conditions.
A coil has an inductance 20 mH. The inductive reactance is 100
Ω. Find the line frequency. Correct Answers 796 Hz
A coil with an inductance of 0.2 H is connected to a 120 V, 60
Hz supply. Find: Correct Answers (a) 75.4 ©, (b) 1.59 A
,A conductor's resistance to current flow is dependent on the
following factors. Correct Answers Type of material, length,
diameter and temperature.
A DC circuit has 12 volts and a resistance of 300 ohms. The
current flowing is___________. Correct Answers 40 milliamps
A dual supply system is one in which two independent power
lines are used to __________ the same load. Correct Answers
supply
A fluidized bed of limestone, will not only reduce nitrous oxides
but will also significantly reduce sulphur dioxide emissions by
the combination of sulphur dioxide with the limestone. Correct
Answers True
A fuel gas line 500 m long is installed in a plant at an ambient
temperature of 20°C. When in service the line will carry fuel gas
at 250°C. How much will the line increase in length when put
into service? Correct Answers 1.26 m
A lagging current means: Correct Answers Voltage peaks
before the current
A magnetic field is always considered to travel from
_____________. Correct Answers north to south
A proper natural gas flame will be blue with a yellow tip.
Correct Answers True
,A resistance of 50 Ω is connected in series with an inductive
reactance of 70 Ω and a capacitive reactance of 20 Ω. What is
the impedance of the circuit? Correct Answers 70.71 Ω
A resistance of 60 Ω is connected in series with an inductive
reactance of 50 Ω and a capacitive reactance of 40 Ω. What is
the impedance of the circuit? Correct Answers 60.83 Ω
A resistor has a maximum loading current of 2 amps and a
power rating of 1.5 watts. The resistance is ________. Correct
Answers 375 milliohms
A seamless, welded, full-hemispherical head is welded to a
boiler shell that has an inside diameter of 1100 mm. Maximum
working pressure is 3500 kPa, the material is SA-226, and
operating temperature is 300°C. The head has a flanged in
manhole that meets code requirements. Calculate the minimum
required thickness for the head. Correct Answers 45.55 mm
A second stator ground fault will cause extensive damage by:
Correct Answers Shorting out parts of the field winding.
Causing high unit vibrations.
Causing rotor heating from unbalanced currents
A simple electric circuit consists of _________________.
Correct Answers conductor, load, source
A single-phase circuit has meter readings of 20 A, and 220 V.
The power factor is 78.8%. Calculate:
(a) The real power of the circuit
, (b) The imaginary power of the circuit Correct Answers (a)
3467 W, (b) 2709 W
A solenoid has 60 Hz supplied at 110 V and inductance of 0.6
H. The current flowing is _________________. Correct
Answers 48.66 amps
A solenoid has 60 Hz supplied at 110 V and inductance of 0.6
H.The inductive resistance is: Correct Answers 226.08 ohms
A steam header between the boiler and first stop valve is to be
fabricated of 152.4 mm O.D. pipe. The material specification is
SA-369 FPA seamless pipe. The operating pressure will be 8440
kPa at 420°C. The pipe will be joined by full penetration welds
and will be fully radiographed. Calculate the minimum thickness
of the pipe wall if the manufacturer's tolerance is 12.5%. Correct
Answers 10.90 mm
A steam line 200 m long is installed in a plant at an ambient
temperature of 15°C. When in service the line will carry steam
at 400°C. How much will the line increase in length when put
into service? Correct Answers 0.847 m
A three phase generator has a terminal voltage of 480 V and
delivers full load current of 300 A per terminal at a lagging
power factor of 75 percent. Calculate:
(a) The apparent power in kilovoltamperes
(b) The full load real power in kilowatts Correct Answers (a)
249.12 kVA, (b) 186.84 kW
Questions With Complete Solutions
________ valve bodies in general can be used on water service
up to temperatures of about 250°C. Correct Answers Cast-iron
__________ are used to convert physical quantities of flow,
level, temperature, pressure, and weight into electrical signals
that represent those quantities as accurately as possible. Correct
Answers Transmitters
A 3-ohm resistor has a power rating of 1.5 watts. The maximum
loading is ______________. Correct Answers 0.707 amps
A boiler drum is made of SA-515-70 steel and has a ligament
efficiency of 0.66. If the steam temperature is 280°C and the
inside diameter of the drum is 1.6 m and the thickness of the
drum is 68.45 mm. What will the maximum operating pressure
be, in kPa? Correct Answers 6500 kPa
A circuit breaker is an automatic device that
______________________. Correct Answers indicates circuit
status.
opens under abnormally high current conditions.
A coil has an inductance 20 mH. The inductive reactance is 100
Ω. Find the line frequency. Correct Answers 796 Hz
A coil with an inductance of 0.2 H is connected to a 120 V, 60
Hz supply. Find: Correct Answers (a) 75.4 ©, (b) 1.59 A
,A conductor's resistance to current flow is dependent on the
following factors. Correct Answers Type of material, length,
diameter and temperature.
A DC circuit has 12 volts and a resistance of 300 ohms. The
current flowing is___________. Correct Answers 40 milliamps
A dual supply system is one in which two independent power
lines are used to __________ the same load. Correct Answers
supply
A fluidized bed of limestone, will not only reduce nitrous oxides
but will also significantly reduce sulphur dioxide emissions by
the combination of sulphur dioxide with the limestone. Correct
Answers True
A fuel gas line 500 m long is installed in a plant at an ambient
temperature of 20°C. When in service the line will carry fuel gas
at 250°C. How much will the line increase in length when put
into service? Correct Answers 1.26 m
A lagging current means: Correct Answers Voltage peaks
before the current
A magnetic field is always considered to travel from
_____________. Correct Answers north to south
A proper natural gas flame will be blue with a yellow tip.
Correct Answers True
,A resistance of 50 Ω is connected in series with an inductive
reactance of 70 Ω and a capacitive reactance of 20 Ω. What is
the impedance of the circuit? Correct Answers 70.71 Ω
A resistance of 60 Ω is connected in series with an inductive
reactance of 50 Ω and a capacitive reactance of 40 Ω. What is
the impedance of the circuit? Correct Answers 60.83 Ω
A resistor has a maximum loading current of 2 amps and a
power rating of 1.5 watts. The resistance is ________. Correct
Answers 375 milliohms
A seamless, welded, full-hemispherical head is welded to a
boiler shell that has an inside diameter of 1100 mm. Maximum
working pressure is 3500 kPa, the material is SA-226, and
operating temperature is 300°C. The head has a flanged in
manhole that meets code requirements. Calculate the minimum
required thickness for the head. Correct Answers 45.55 mm
A second stator ground fault will cause extensive damage by:
Correct Answers Shorting out parts of the field winding.
Causing high unit vibrations.
Causing rotor heating from unbalanced currents
A simple electric circuit consists of _________________.
Correct Answers conductor, load, source
A single-phase circuit has meter readings of 20 A, and 220 V.
The power factor is 78.8%. Calculate:
(a) The real power of the circuit
, (b) The imaginary power of the circuit Correct Answers (a)
3467 W, (b) 2709 W
A solenoid has 60 Hz supplied at 110 V and inductance of 0.6
H. The current flowing is _________________. Correct
Answers 48.66 amps
A solenoid has 60 Hz supplied at 110 V and inductance of 0.6
H.The inductive resistance is: Correct Answers 226.08 ohms
A steam header between the boiler and first stop valve is to be
fabricated of 152.4 mm O.D. pipe. The material specification is
SA-369 FPA seamless pipe. The operating pressure will be 8440
kPa at 420°C. The pipe will be joined by full penetration welds
and will be fully radiographed. Calculate the minimum thickness
of the pipe wall if the manufacturer's tolerance is 12.5%. Correct
Answers 10.90 mm
A steam line 200 m long is installed in a plant at an ambient
temperature of 15°C. When in service the line will carry steam
at 400°C. How much will the line increase in length when put
into service? Correct Answers 0.847 m
A three phase generator has a terminal voltage of 480 V and
delivers full load current of 300 A per terminal at a lagging
power factor of 75 percent. Calculate:
(a) The apparent power in kilovoltamperes
(b) The full load real power in kilowatts Correct Answers (a)
249.12 kVA, (b) 186.84 kW
