WorksheetsT&D Unit 5
Total questions: 30
Worksheet time: 30mins
The rated voltage of a 3 phase power system is given by
RMS peak voltage
Peak phase voltage
RMS line to line voltage
Peak line to line voltage
Which of these systems uses the 3 phase 4 wire system?
Primary transmission
Primary distribution
Primary distribution
Secondary distribution
Greater the power factor the ________________ is the volume of copper required.
Greater
Smaller
Both are equal
Depending on the level of transmission
Line efficiency increases for ________ transmission voltages.
Higher
Lower
Either higher or lower
None of the options
The most important disadvantage of using the high voltage for transmission is
The increased cost of insulating the conductors.
The increased cost of transformers, switchgear and the other terminal apparatus
Both the options
Reduction in corona loss
The most suitable practical value of primary distribution is?
66 KV
6.6 KV
230V / 400V
22 KV
For the same conductor length, same amount of power, same losses and maximum voltage to earth, which system requires minimum conductor area?
3 wire ac
2 wire ac
2 wire dc
single phase
What is the highest transmission voltage in India at present?
675 KV
765 KV
132 KV
440 KV
What does the point P refer to in the attached diagram?
Most economical power transmission
Most economical area of cross section
Both the above options
Most ideal point of transmission
Which material is used for the manufacture of ground wire?
Aluminium
Cast iron
Stainless steel
Galvanised steel
Which component connects the substation to the area where power is to be distributed?
Distributors
Service mains
Feeders
All of these
Name the cable which connects the distributor to the consumer terminals.
Distributors
Service mains
Feeders
All of these
Where are the radial systems generally employed?
Where power is generated at low voltage
Where power is generated at high voltage
Where power is generated at low voltage and substation is located at the centre of the load
Where power is generated at high voltage and substation is located at the centre of the load
What is the main advantage of ring main system over radial system?
i. Voltage drop in the feeder is less.
ii. Power factor is higher.
iii. Supply is more reliable.
i and ii only
ii and iii only
i and iii only
i, ii and ii
The null point of a uniformly loaded distributor feed at equal voltage at both ends lies at
Mid point
Either end
Two third distance from one end
One fourth distance from one end
In a distribution system, which of the following items forms the major cost?
Conductors
Earthing systems
Distribution transformers
Insulators
Which type of distribution is preferred in residential areas?
Single phase, two wire
Three phase, three wire
Three phase, four wire
Two phase, four wire
Which distribution system is energised by two or more generating stations or substations?
Radial systems
Interconnected systems
Ring main systems
All of these
A uniformly loaded dc distributor is fed at both ends with equal voltages. In comparison to a similar distributor fed at one end only, what will be the maximum voltage drop?
One fourth
Half
One third
One sixth
Installation of capacitors at suitable locations and of optimum size in a distribution system results in
i. Improved voltage regulation.
ii. Reduction in distribution power losses.
iii. Reduction of kVA rating of distribution transformers
(i) only
(i) and (ii) only
(iii) only
All of the these
Why is the floating neutral in a three phase supply considered as undesirable?
High voltage across the load
Low voltage across the load
Unequal line voltages across the load
None of the above
An industrial consumer has a load pattern of 2000 kW, 0.8 lag for 12 hours and 1000 kW UPF for 12 hours. What is its load factor?
10.5
0.75
0.6
2.0
The power factor of industrial loads is generally
Unity
Lagging
Leading
Any of the options
The voltage at the receiving end of a long transmission line on no load can be regulated by
shunt resistors
shunt inductors
shunt capacitors
none of the above
In a substation, the following equipment is not installed
Exciters
Series capacitors
Shunt reactors
Voltage transformers
A synchronous motor can be used to improve the power factor of a factory by
varying stator frequency
Increasing the field excitation
Reducing the field excitation
varying stator voltage
Which of the following equipment, for regulating the voltage in distribution feeder, will be most economical?
Static condenser
Tap changing transformer
synchronous condenser
shunt capacitor
HVDC systems use 12 pulse rectifiers since
the converter cost becomes less
transformers are not required
there will be no earth fault current
the voltage ripple is reduced
Arcing ground may take place if the neutral is
Resistance grounded
Reactance grounded
Solid grounded
Ungrounded
Gas insulated substations may normally use
Oxygen
Nitrogen
Carbondioxide
Sulphur hexafluoride
