Ques 1. By which of the following method electric power may be transmitted from one location to another location?
Undergrounds System
Overhead system
Both 1 and 2
None of the above
Answer 3. Both 1 & 2
Explanation: Electrical power is generally transmitted by two methods i.e underground transmission and overhead transmission
Ques 2. Which of the following transmission line have more initial cost?
Overhead Transmission
Underground transmission
Both have almost the same initial cost
None of the above
Answer 2. Underground Transmission line
Explanation:
The underground cable can be 2-3 times more expensive than the overhead cable.
As the voltage level increases the cost of insulation is increased therefore the underground cable is restricted to low and medium voltages.
Ques 3. Name the cable or conductor which connects the distributor to the consumer terminals.
Service Mains
Distributor
Feeders
None of the above
Answer 1. Service Mains
Explanation:
Service Mains: The service mains conductors form connecting links between distributors and metering points at the consumer terminal.
The area of connection of a sub-main conductor is greater than the service mains.
Ques 4. Which of the following materials are not used for the transmission and distribution of electrical power?
Copper
Aluminum
Tungsten
Steel
Answer 3. Tungsten
Explanation:
The resistance of tungsten is very high, the more the resistance more the losses, therefore, tungsten is never used for transmission and distribution purposes.
Ques 5. The usual spans with R.C.C. poles are
40—50 meters
60—100 meters
200 – 300 meters
80 – 150 meters
Answer 4. 80 – 150 meters
Explanation:
Reinforced concrete pole(R.C.C Pole)
The Reinforced concrete pole (R.C.C) is usually called a Concrete pole and it are used for system voltage up to 33kV.
The minimum overall length of the R.C.C pole should be six meters.
The span length of R.C.C is between 80 – 200 meters because they are stronger and more durable.
They are free from corrosion hence poles have a longer life but these are very bulky in sizes.
Ques 6. Which of the following are the constants of the transmission lines?
Inductance
Capacitance
Resistance
Conductance
All of the above
Answer 5. All of the Above
Explanation:
a b c d constants of the transmission line( Primary line constants)
The line constants are parameters that describe the characteristics of conductive transmission lines.
The primary line has the following constants
R = Resistance per unit length Ω
L = Inductance per unit length (Henry) H
C = Capacitance per unit length (Henry) H
G = Conductance per unit length ℧
All these constants are independent of frequency, therefore, they are called primary constants and these constants are measured by considering both the wires of the transmission lines.
R and L elements are in series with the line (because they are properties of the conductor) and C and G are elements shunting the line (because they are properties of the dielectric material between the conductors).
G represents leakage current through the dielectric and in most cables is very small.
Ques 7. The phenomenon of rising in voltage at the receiving end of the open-circuited or lightly loaded line is called as
Roman Effect
Skin Effect
Corona Effect
Ferranti Effect
Answer 4. Ferranti Effect
Explanation:
Ferranti Effect
The phenomenon of the rise of voltage at the receiving end of an open-circuited or lightly loaded transmission line is called as the Ferranti effect.
The receiving end voltage becomes more than the sending end voltage.
The Ferranti effect occurs in medium and long transmission lines.
The Ferranti Effect will be more pronounced the longer the line and the higher the voltage applied. The relative voltage rise is proportional to the square of the line length.
The Ferranti effect is much more pronounced in underground cables, even in short lengths, because of their high capacitance.
Ques 8. Low tension cables are meant for use up to
1 kV
5 kV
10 kV
33 kV
Answer 1. 1 kV
Explanation: Low voltage cables with a range up to 1 kV are used for energy distribution from the last transformer station to the customer.
Ques 9. The operating voltage of high tension cables is up to
1 – 11 kV
11 – 20 kV
11 – 33 kV
above 33 kV
Answer 1. 1 – 11 kV
Explanation:
High tension cables are used for a three-phase medium. These consist of three core belted type cables with separated insulation for each core.
Paper insulation is provided for high-tension cables.
The operating voltage of high tension cable is up to 11kV.
Ques 10. The operating voltage of super tension cable is
1 – 11 kV
11 – 33 kV
33 – 66 kV
Above 66 kV
Answer 2. 11- 33 kV
Explanation:
Super tension cables are used upto the voltage level of 33 kV. They are further classified into 3 types
