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1.0.0
MCQ
4561. The common fault is overhead distribution system is-
phase to phase fault
one phase to earth fault
all phase short circuited
none of the above
ব্যাখ্যা: About 50-55% fault in overhead distribution system is one phase to earth fault and 12-15% fault is phase in phase fault
4562. At distribution substation voltage is stepped down to-
66kV
132kV
11kV
415/230 Volts
4563. Which of the following is not the distribution system, normally used-
3 phase 4 wire
Single phase-3 wire
Single phase -4 wire
3 phase-3 wire
ব্যাখ্যা 2 AC distribution system can be classified as- -Single phase-2 wire system -Sinele phase-3 wire system -Two phase-3 wire system -Two phase-4 wire system -Three phase-3 wire system -Three phase-4 wire system
4564. Interference between a power line and a communication line is due to-
electromagnetic induction
electrostatic induction
electromagnetic and electrostatic induction.
none of the above
ব্যাখ্যা: Interference is the process in which two or more light, sound or electromagnetic waves of the some frequency combine to reinforce or cancel each other. It is generated by an external source that affects an electrical circuit by electromagnetic induction, electrostatic coupling or conduction
4565. Routing means connecting-
Circuit or equipment to earth
Impent to earth
Circuit to earth
None of the above
ব্যাখ্যা: Routing is the process of selecting a path for traffic in network, circuits or different equipments.
4566. Which is used for power factor improvement?
Spring motor
Sychronous motor
Commutator motor
Squirrel case motor
ব্যাখ্যা: To improve power factor we ute- -Capacitor bank -Synchronous motor -Synchronous condenser -Phase advancer,
4567. Objectives of power system is/are-
Cost of electrical energy per kWh is to be minimum
Rated voltage and frequency has to be supplied to the consumers
both 1 and 2
nether 1 nor 2
4568. Capacitance of a transmission line is the result of-
Potential diference between the conductors
Current flow in both conductors
Current flow in either conductors
Charge per unit current
ব্যাখ্যা: Capacitance of a transmission line is the results due to the potential difference between the conductors. The conductors get charged in the same way as the parallel plates of a capacitor, capacitance between two parallel conductors depends on the size and the spacing between the conductors
4569. Which distribution system is more reliable?
Ring main system
Tree system
Radial System
All are equally reliable
ব্যাখ্যা: The ring main distribution system is more reliable as each distribution transformer is fed with two feeders. That means in the event of a fault in any section of the feeder. the continuity of the supply is ensured from the alternative path.
4570. Length of the cable is doubled, its capacitance C will be-
one-fourth
doubled
one-half
unchanged
ব্যাখ্যা: The length of the cable and the capacitance of the cable are directly proportional to each other. If the length gets doubled, then the capacitance also can be doubled.
4571. Common declared distribution voltage in Bangladesh for low voltage circuit is-
230 Volts
250 Volts
440 Volts
380 Volts
4572. The highest point on the daily load curve represents-
average load
load factor
maximum load
none of the above
4573. The volume of copper required for an ac transmission line is inversely proportional to-
current
voltage
power factor
both b & c
4574. Permissible variation in power frequency in Bangladesh is-
±0.1%
±1%
±5%
±10%
4575. Corona is affected by-
condition of atmosphere
line voltage
size & spacing of conductor
all of the above
4576. The surge impedance for over head line is taken as-
10-202 Ω
100-200 Ω
50-600 Ω
1000-2000Ω
4577. TStability of a system is not affected by-
Reactance of line
Losses
Reactance of generator
Output torque
ব্যাখ্যা: Stability of power system is affected by- -Reactance of transmission line -Reactance of generator -Excitation of generator -Input output torque.
4578. When the load factor of a power station increases, the units (kwh) generated-
are increased
remain the same
are decreased
none of these
4579. the minimum phase -neutral voltage at which corona occurs, is called-
critical disruptive voltage
visual critical voltage
fieash over voltage
none of the above
4580. Potential difference to any equal charge is measured in,
coulomb
Ampere
joule
volt
ব্যাখ্যা: The unit of potential difference between any two equal charges is volt.