AP ECET EEE 2019-6

1. The principle of operation of a 3 phase induction motor is almost similar to that of

A. synchronous motor
B. repulsion start induction motor
C. transformer with a shorted secondary
D. capacitor start induction motor

Answer : transformer with a shorted secondary
Explanation:-

2. Armature reaction in a synchronous motor at rated voltage and zero power factor (lead) is

A. magnetising
B. cross magnetising
C. both magnetising and cross magnetising
D. demagnetising

Answer : demagnetising
Explanation:-

3. The transformer efficiency at relatively light loads is quite low. This is due to

A. Small copper losses
B. Small secondary output
C. High fixed loss in comparison to the output
D. poor power factor

Answer : High fixed loss in comparison to the output
Explanation:-

4. The main criterion for selection of the size of a distributor for a radial distribution system is________

A. voltage drop
B. corona loss
C. temperature rise
D. capital cost

Answer : voltage drop
Explanation:-

5. If the differential and common mode gains of a differential amplifier are 50 and 0.2 respectively, then the CMRR will be____________

A. 10
B. 49.8
C. 50.2
D. 250

Answer : 250
Explanation:-
Given Differential gain(Ad)= 50, Common mode gain(Acm) = 0.2
Common Mode Rejection Ratio(CCMR)=Ad/(Acm)=50/0.2=250

6. Three 30 ohm resistors are connected in parallel across an ideal 40V source. what would be the equivalent resistance seen by the load connected across the circuit

A. 0 ohm
B. 10 ohm
C. 20 ohm
D. 30 ohm

Answer : 0 ohm
Explanation:- Ideal Voltage source has zero internal Resistance(Short Circuit)
So equivalent resistance across Load is 0 Ohms

7. Capacitance grading of cable means_______

A. use of dielectrics in different concentrations
B. introduction of capacitances at various lengths of cable to counter the effect of inductance
C. use of dielectrics in different permittivities
D. grading according to capacitance per km length of the cable

Answer : use of dielectrics in different permittivities
Explanation:-

8. Two bulbs of 100W/250V and 150W/250V are connected in series across a supply of 250V. The power consumed by the circuit is________________

A. 30 W
B. 60 W
C. 100 W
D. 250 W

Answer : 60 W
Explanation:-

9. For a medium length transmission line, A is ____

A. equal to B
B. equal to C
C. equal to D
D. not equal to B,C,D

Answer : equal to D
Explanation:-

10. The composite system (single phase AC to DC system) has been chosen for all future track electrification in India as_____

A. it needs light overhead catenary
B. it needs less number of substations
C. It combines the advantages of High voltage AC distribution at 50Hz with DC series traction motors
D. it provides flexibility in the location of substation

Answer : It combines the advantages of High voltage AC distribution at 50Hz with DC series traction motors
Explanation:-