Notes

4)Which of the following are true about Induction Motors (IM).
a. Slip ring IM has high starting torque than squirrel cage IM
b.Brushes are present in slip ring IM
C.Brushes are present in squirrel cage IM
d.Squirrel cage IM has high starting torque than slip ring IM e.Squirrel cage IM are costlier than slip ring IM
i) a&b -BING
ii)a&c
ii)a, c& e
iv)c, d& e -CHATGPT
v)b&d -BARD

5)The core flux in transformer depends on i)Supply voltage
ii)Supply voltage, frequency, and permeability of the core material -CORRECT
iii)Supply voltage, frequency, and load current
iv)supply voltage & load, but independent of frequency
v)Supply voltage & frequency

6)The net core area of a 1-Phase, 600 /120 V, 50 Hz transformer is 50 cm2 and the maximum flux density is 1.6 Wb/m2. The number of turns of primary and secondary are respectively,
i)600 & 120
ii) 4&1
iii)338 & 68 -CORRECT
iv)478 & 96

9)Why is 3-Phase power used for electrical power transmission? Why not 6, 12 or more?
i)It is not possible to achieve more than 3 phases due to space constraints.
ii)It becomes non-economical in a practical scenario due to increased cost materials, complex design, and additional maintenance. -CORRECT
iii) The voltages and currents become unbalanced in 6,12 or more phases.
iv)Power transmission capability will be reduced since there will be more losses.

8)For a balanced 3-Phase star and delta connected circuit, respectively,
i)Phase voltages are 30 degrees ahead of their corresponding line voltages; line currents are lagging 30 degrees to their corresponding phase currents
ii)Phase voltages are lagging 30 degrees to their corresponding line voltages; line currents are lagging 30 degrees to their corresponding phase currents -CHATGPT
iii)Line voltages are lagging 30 degrees to their corresponding phase voltages; phase currents are ahead 30 degrees to their corresponding line currents -BARD
iv)Line voltages are 30 degrees ahead to their corresponding phase voltages; line currents are 30 degrees ahead to their corresponding phase currents -BING

11)Pick the odd one out.
a. Tesla Model S, Tesla Model X - Three Phase AC Induction Motor
b.Tata Motors Nexon EV, Nissan Leaf EV -Permanent Magnet Synchronous Motor
C.Tesla Model 3 - Brushed DC Motor
d. Ather Energy Scooters, Hero Electric, Yamaha - Brushless DC Motor
e. Mahindra e-Verito, Tata Tigor - Servo Motors

i)b&d
ii)e
iii) c -CORRECT
iv)a&d
v)c&e

17)Why does the transformer not rotate like an induction motor? Choose the best reason from the following.

i)Transformer is used to step up/down voltage while in-duction motor is involved in rotation.
ii)Brakes are attached to the transformer coils. -CHATGPT(2ND TIME)
iii)Both have different principles of working. -CORRECT
iv)In transformer the three-phase winding are not 120° apart in space unlike an induction motor

18)Which of the following is true about generators?
a. Thermal generators are wound for less number of poles than hydro generators
b. Hydro generators are wound for less number of poles than thermal generators
c. Thermal generators are of cylindrical rotor type and hydro generators are of salient pole rotor type
d. Hydro generators are of cylindrical rotor type and thermal generators are of salient pole rotor type

i) b&d -BARD
ii) a&c
iii) a&d -CHATGPT
iv)b&c -BING

19)Which statutory body is responsible to ensure the integrated operative of the national grid in a reliable, efficient and secure manner?
i) Central Electricity Authority
ii)Central Electricity Regulatory Commission
iii)Power System Operation Corporation Limited -CORRECT
iv)Ministry of Power
v)Power Grid Corporation of India Limited

20)Who is the Central Transmission Utility
(CTU) in India?
i)Central Electricity Regulatory Commission
ii)Power Grid Corporation of India Limited -CORRECT
iii)National Load Dispatch Center
iv)Central Electricity Authority

21)Under certain operating condition the rotor current frequency of 50 Hz, 4-Pole, 3-Phase
Induction Motor is found to be 2.5 Hz. The slip and speed of the motor under this condition are respectively, (1 Point)
i)5 % and 1462.5 RPM -CHATGPT,BARD
ii) 4 % and 1440 RPM
iii) 4% and 1425 RPM
iv) 5 % and 1425 RPM -BING

22)What is the role of the iron core in a step-up transformer? (1 Point
i) It provides coupling between primary and secondary
ii) It increases the magnitude of mutual flux
iii)It reduces the magnitude of magnetizing current
iv)All the above -CORRECT
v) None of the above

23)Which of the following is true about a transformer?
а)Converts low voltage AC to high voltage AC without change in frequency b)Works on principle of mutual induction
c)Converts high voltage AC to low voltage AC without change in power d)Ratings are given in VA

i) a&d
ii) a, c, & d
iii) a, b, c, & d -BARD,CHATGPT(2ND TIME)
iv)a, b, & c -BING,CHATGPT(1ST TIME)

16)Pick the correct order about the latest fuel wise installed generation capacity in India
i)Coal > Solar > Hydro > Wind > Nuclear - BARD
ii) Coal > Hydro > Solar > Wind > Nuclear - BING
iii)Coal > Hydro > Nuclear > Wind > Solar
iv)Coal > Hydro > Wind > Solar > Nuclear - CHATGPT
v)Hydro > Coal > Nuclear > Wind > Solar

15)Can power transmission be done at unity power factor? (1 Point)
i) No, most loads generate reactive power.
ii)No, most loads are motors, electromagnets, transformers which use magnetic fields for their operation that require reactive power. -BARD
iii)Yes, it will allow to transmit more power. -CHATGPT,BING
iv)Yes, it will lead to reduced losses. -BING

14)Regarding power transmission links in India listed below, select the option which is different from others.

i)Biswanath Chariali - Agra, 800 KV
ii) Agra - Greater Noida - New, 765 KV -BARD
iii)Raipur-Chandrapur, 400 kV -BING,CHATGPT
iv)Raichur-Sholapur, 765 KV
b)Vindhyachal - Varanasi, 765 KV

13)Which device is used in electrical power systems and telecommunication systems to protect the insulation and conductors from the damaging effects of lightening?

i)Protective Relays
ii)Surge Arrestor -CORRECT
iii)Wave Trap
iv)Circuit Breaker

10)Consider three cores made up of Fe, Al and wood having the same dimensions and are wound with same number of turns. If these cores are fed from the same voltage at a fixed frequency, then the order relating to the magnitudes of magnetizing current will be:

i)Fe> Al> Wood -CHATGPT,BARD
ii) Wood > Al> Iron -BING
iii) Al> Wood > Iron
iv) Al> Fe> Wood

7)Which of the following will take least time in starting from cold condition to full load operation?

i)Thermal Power Plant
ii) Hydroelectric Power Plant -BARD
iii)Gas Turbine Power Plant -CHATGPT,BING
iv)Nuclear Power Plant