163 + Interview Questions in Induction Machines in Electrical Machines Page 2 InterviewSolution

51.	The external rotor resistance is ____________(a) gradually cut out as motor picks up the speed(b) fixed for a stable point(c) removed instantalLy as the motor is started(d) added or reduced as per the efficiency requirementThe question was asked during an internship interview.The question is from Determination of Equivalent Circuit Parameters in division Induction Machines of Electrical Machines
Answer» The correct answer is (a) GRADUALLY cut out as motor picks up the SPEED Explanation: External resistance is gradually cut out after PICKING up the speed.

Discussion

52.	Blocked rotor test comprises of ____________(a) rotor and stator copper losses.(b) rotor copper and stator core losses.(c) rotor core losses(d) stator copper lossesThis question was addressed to me during an interview for a job.Asked question is from Determination of Equivalent Circuit Parameters topic in chapter Induction Machines of Electrical Machines
Answer» The correct answer is (a) ROTOR and stator copper losses. Easy EXPLANATION: BLOCKED rotor test CONSISTS of copper losses of stator and rotor WINDING copper losses.

Discussion

53.	A 3-phase, 50 Hz, 6-pole induction motor has a shaft output of 10kW at 930 rpm. Friction and windage losses is 1% of the output. Total stator losses is 600W. What is the stator input?(a) 10860 W(b) 10100 W(c) 11460 W(d) 11000 WI had been asked this question in an interview.Origin of the question is Operating (or Performance) Characteristics of Induction Motors topic in chapter Induction Machines of Electrical Machines
Answer» The CORRECT OPTION is (c) 11460 W Explanation: Full load slip = 1000-930/1000 = 0.07. Friction losses = 0.01*10000 = 100 W Pm = 10000+100 = 10100 W Rotor input = 10100/0.93 = 108060 W Stator input = Pg+600 = 11460 W.

Discussion

54.	A 3-phase, 50 Hz, 6-pole induction motor has a shaft output of 10kW at 930 rpm. Friction and windage losses is 1% of the output. Total stator losses is 600W. What is the rotor input?(a) 10860 W(b) 10100 W(c) 11460 W(d) 11000 WI got this question in an interview for job.Query is from Operating (or Performance) Characteristics of Induction Motors in chapter Induction Machines of Electrical Machines
Answer» Correct answer is (a) 10860 W The explanation is: FULL load SLIP = 1000-930/1000 = 0.07. Friction LOSSES = 0.01*10000 = 100 W Pm = 10000+100 = 10100 W Rotor input = 10100/0.93 = 108060 W

Discussion

55.	Mark the stable operating point when the load torque shifts from Tl1 to Tl2.(a) A(b) A,B(c) B,C(d) A,CI have been asked this question in unit test.This intriguing question originated from Operating (or Performance) Characteristics of Induction Motors in chapter Induction Machines of Electrical Machines
Answer» The correct choice is (a) A Easy explanation: For the STABLE operation, (dTl/dn)>(dTe/dn).

Discussion

56.	The stable point to use the induction motor possesing the below characteristic.(a) C(b) D(c) C and D(d) Machine will not startThis question was posed to me in an interview for internship.Origin of the question is Operating (or Performance) Characteristics of Induction Motors in portion Induction Machines of Electrical Machines
Answer» RIGHT option is (a) C To explain: For the STABLE OPERATION, (dTl/dn)>(dTe/dn).

Discussion

57.	At which point shall the induction machine be operated to attain a stable operation?(a) The machine will not start(b) A(c) B(d) Both A as well as BI had been asked this question in an interview for internship.I'm obligated to ask this question of Operating (or Performance) Characteristics of Induction Motors in portion Induction Machines of Electrical Machines
Answer» CORRECT OPTION is (a) The MACHINE will not start Easy EXPLANATION: NONE.

Discussion

58.	The stable point in the operation of the induction motor is?(a) C(b) D(c) B(d) AI have been asked this question in a job interview.My question is based upon Operating (or Performance) Characteristics of Induction Motors in chapter Induction Machines of Electrical Machines
Answer» Right option is (a) C Explanation: If the load TORQUE SHIFT to the Tl2, the motor SPEED will INCREASE while load torque DECREASES.

Discussion

59.	For a three phase induction motor, maximum torque is double the full load torque and starting torque is 1.6 times the full load torque. To get a full load slip of 5%, percentage reduction in the rotor resistance should be?(a) 62.7%(b) 75%(c) 60%(d) 35%This question was posed to me in unit test.I want to ask this question from Operating (or Performance) Characteristics of Induction Motors in portion Induction Machines of Electrical Machines
Answer» Correct answer is (a) 62.7% To EXPLAIN I would say: Slip at which MAXIM torque occurs is calculated as smT=0.5. r2/x2=0.5 for full load slip of 0.05,1/2 = 2/((0.05/sf)+(sf/0.05)) smT2 = 0.186 reduction in resistance = (0.5×2-0.186×2)/0.5×2 = 63%.

Discussion

60.	A 10 kW, 400 V, 3-phase, 4-pole, 50 Hz induction motor develops the rated output at rated voltage with its slip rings shorted. The maximum torque is twice the full load torque occurs at the slip of 10% with zero external resistance in the rotor circuit. An external resistance is now tripled in the rotor circuit. Then the stator current will _________(a) remain constant(b) increase(c) decrease(d) any of the mentionedI had been asked this question by my school principal while I was bunking the class.My doubt is from Operating (or Performance) Characteristics of Induction Motors topic in section Induction Machines of Electrical Machines
Answer» The correct ANSWER is (a) remain constant To explain: As the RATIO of r2/s is constant, the changes will not be reflected to the STATOR.

Discussion

61.	A 10 kW, 400 V, 3-phase, 4-pole, 50 Hz induction motor develops the rated output at rated voltage with its slip rings shorted. The maximum torque is twice the full load torque occurs at the slip of 10% with zero external resistance in the rotor circuit. An external resistance is now tripled in the rotor circuit. Then the slip at which maximum torque occur for the same load torque is?(a) 0.3(b) 0.268(c) 0.03(d) 3This question was posed to me in final exam.The doubt is from Operating (or Performance) Characteristics of Induction Motors in portion Induction Machines of Electrical Machines
Answer» Correct option is (a) 0.3 Explanation: The LOAD torque is maintained constant. So, r2/smT = X; r2/x = 0.1 new VALUE of SLIP will be, 3*r2/x=0.1 smT = 0.3.

Discussion

62.	A 10 kW, 400 V, 3-phase, 4-pole, 50 Hz induction motor develops the rated output at rated voltage with its slip rings shorted. The maximum torque is twice the full load torque occurs at the slip of 10% with zero external resistance in the rotor circuit. The speed at the full load torque will be?(a) 1460 rpm(b) 1400 rpm(c) 1360 rpm(d) 1470 rpmThe question was asked in an interview.Question is taken from Operating (or Performance) Characteristics of Induction Motors topic in section Induction Machines of Electrical Machines
Answer» The correct CHOICE is (a) 1460 rpm To EXPLAIN I WOULD say: 1/2 = 2/((0.1/sf)+(sf/0.1)) s = 2.68% rotor speed = (1-0.0268)=1460rpm.

Discussion

63.	A 10 kW, 400 V, 3-phase, 4-pole, 50 Hz induction motor develops the rated output at rated voltage with its slip rings shorted. The maximum torque equal to twice the full load torque occurs at the slip of 10% with zero external resistance in the rotor circuit. The slip at the full load torque will be?(a) 2.7%(b) 5%(c) 3.7%(d) 10%The question was asked in an interview for job.My enquiry is from Operating (or Performance) Characteristics of Induction Motors in section Induction Machines of Electrical Machines
Answer» CORRECT answer is (a) 2.7% To EXPLAIN I would SAY: Tfl/Tem = 2/((sm/sf)+ (sf/sm)) 1/2 = 2/((0.1/sf)+(sf/0.1)) s^2-0.4s+0.01=0 s=0.0268.

Discussion

64.	In the 3-phase induction motor developed torque during plugging is ______ mechanical power developed in the braking region of the induction motor is ______(a) positive, negative(b) negative, positive(c) positive, positive(d) negative, negativeI had been asked this question at a job interview.My doubt is from Analysis of the Equivalent Circuit topic in portion Induction Machines of Electrical Machines
Answer» Right OPTION is (a) positive, NEGATIVE For explanation: TEM is positive while PM will be negative in braking or plugging operation.

Discussion

65.	At starting, developed mechanical power is _____ and developed torque is ______(a) zero, not zero(b) zero,zero(c) not zero, zero(d) not zero, maximumI have been asked this question during an interview.My question is from Analysis of the Equivalent Circuit topic in chapter Induction Machines of Electrical Machines
Answer» Right choice is (a) ZERO, not zero Explanation: At START, TORQUE is not zero. P α (1-s)/s; so it is zero at s = 1.

Discussion

66.	Developed torque during plugging is _________(a) negative(b) positive(c) zero(d) any of the mentionedI had been asked this question in examination.This intriguing question comes from Analysis of the Equivalent Circuit in section Induction Machines of Electrical Machines
Answer» CORRECT option is (b) positive The explanation: TORQUE will not be NEGATIVE in BRAKING MODE in the induction motor.

Discussion

67.	Mechanical power developed in the braking region of the induction motor is _________(a) negative(b) positive(c) zero(d) any of the mentionedThis question was addressed to me by my college professor while I was bunking the class.This intriguing question comes from Analysis of the Equivalent Circuit topic in section Induction Machines of Electrical Machines
Answer» The CORRECT option is (a) NEGATIVE Easiest EXPLANATION: slip is more than ONE, so Pm will be negative.

Discussion

68.	Changing the rotor resistance will also affect _________(a) starting torque, speed, current(b) maximum torque, speed, current(c) maximum torque, speed, current, starting torque(d) speed and currentThis question was posed to me in examination.My question is from Analysis of the Equivalent Circuit in division Induction Machines of Electrical Machines
Answer» The CORRECT answer is (a) starting torque, speed, current The best I can explain: Rotor resistance does not alter the MAXIMUM torque of the INDUCTION MACHINE.

Discussion

69.	Slip greater than unity is obtained practically by _________(a) plugging(b) changing phase sequence(c) changing stator leads(d) any of the mentionedThis question was posed to me during an internship interview.My question is taken from Analysis of the Equivalent Circuit in portion Induction Machines of Electrical Machines
Answer» CORRECT choice is (d) any of the mentioned Easy explanation: The DIRECTION of the rotating field can be reversed by any ONE of the methods.

Discussion

70.	Torque produced by induction generator is negative.(a) True(b) FalseI got this question during an interview for a job.I want to ask this question from Analysis of the Equivalent Circuit topic in division Induction Machines of Electrical Machines
Answer» The correct option is (a) True Explanation: Because the developed TORQUE is PRODUCED OPPOSITE to the rotating FIELD.

Discussion

71.	When an induction generator is connected to an infinite bus, it _________(a) requires no capacitor bank(b) requires star connected capacitor bank(c) requires delta connected capacitor bank(d) requires any capacitor bankThis question was addressed to me in an internship interview.Question is taken from Analysis of the Equivalent Circuit in division Induction Machines of Electrical Machines
Answer» The correct option is (a) requires no capacitor bank Explanation: There is no requirement of the capacitor bank when INDUCTION generator is connected to INFINITE BUS.

Discussion

72.	Induction generator is equivalent to _________(a) underexcited alternator(b) dc generator(c) over excited alternator(d) leading over excited alternatorI had been asked this question in an interview.The question is from Analysis of the Equivalent Circuit in chapter Induction Machines of Electrical Machines
Answer» RIGHT CHOICE is (a) underexcited ALTERNATOR Easiest EXPLANATION: It is SIMILAR to underexcited alternator.

Discussion

73.	If it is desired to approximate the efficiency of an induction motor operating at slip ‘s’, then its efficiency is given by?(a) 1-s/1+s(b) 1/1+s(c) s/s+1(d) s/1-sI have been asked this question in homework.My question is from Equivalent Circuit in section Induction Machines of Electrical Machines
Answer» RIGHT choice is (a) 1-s/1+s The best I can EXPLAIN: APPROXIMATELY EFFICIENCY is given as 1-s/1+s for an IM.

Discussion

74.	Below is the torque slip characteristic of the induction machine. What can be inferred from it?(a) R22 > R21(b) R22 < R21(c) R22 = R21(d) R22 = -R21This question was posed to me by my college professor while I was bunking the class.My enquiry is from Analysis of the Equivalent Circuit topic in portion Induction Machines of Electrical Machines
Answer» RIGHT choice is (a) R22 > R21 The BEST explanation: As rotor resistance increases, the STARTING TORQUE will increase but not the maximum torque. But the slip at which the maximum torque occurs will CHANGE.

Discussion

75.	A delta connected capacitance bank is preferred over a star connected bank. This is done to ensure _________(a) lesser capacitance(b) easy calculation(c) easier connection(d) all of the mentionedThis question was posed to me in final exam.Enquiry is from Equivalent Circuit in section Induction Machines of Electrical Machines
Answer» The CORRECT option is (a) lesser capacitance Easiest explanation: DELTA connected BANK will have lesser capacitance than star connected and so the better POWER FACTOR improvement.

Discussion

76.	A star connected capacitor bank is connected to the induction motor having capacitance C and VA rating as VAs. If the capacitor bank is replaced by a delta bank then?(a) C = C/3, VA = VAs(b) C = 3C, VA = VAs(c) C = C, VA = VAs/3(d) C = C/3, VA = VAs/3I have been asked this question in homework.Question is from Equivalent Circuit topic in division Induction Machines of Electrical Machines
Answer» Right option is (a) C = C/3, VA = VAs Explanation: The VA rating will not CHANGE DUE the CONFIGURATION, but the capacitance will change due to the delta configuration to C/3.

Discussion

77.	A 3-phase induction machine is running at super synchronous speed. For the machine to be self excited it _________(a) draws reactive power from mains(b) draws real power from mains(c) feeds reactive power to mains(d) generates emf by gradual voltage build upI had been asked this question in an internship interview.Asked question is from Equivalent Circuit in chapter Induction Machines of Electrical Machines
Answer» The correct option is (a) DRAWS REACTIVE power from mains Explanation: To provide the reactive power for the MACHINE, it will draw reactive power from a SOURCE.

Discussion

78.	Induction generators will deliver power at _________(a) leading p.f.(b) lagging p.f.(c) unity p.f.(d) zero p.f.I have been asked this question in class test.Question is from Equivalent Circuit in chapter Induction Machines of Electrical Machines
Answer» CORRECT CHOICE is (a) leading p.f. For EXPLANATION I would SAY: Induction generator will deliver power at leading p.f.

Discussion

79.	In a 3-phase induction generator which is self excited, load has been increased. To keep the frequency of the generated voltage constant, speed of the induction machine should be _________(a) increased(b) decreased(c) maintained less than rated synchronous speed(d) maintained more than rated synchronous speedI got this question during an internship interview.Question is taken from Equivalent Circuit topic in section Induction Machines of Electrical Machines
Answer» Right OPTION is (a) INCREASED For EXPLANATION: FREQUENCY should be increased to maintain the speed constant.

Discussion

80.	At standstill the equivalent of the 3-phase induction motor is similar to _________(a) short-circuitedtwo winding transformer(b) open circuit two winding transformer(c) stand still synchronous motor(d) none of the mentionedThis question was addressed to me in an interview for internship.I'd like to ask this question from Equivalent Circuit in chapter Induction Machines of Electrical Machines
Answer» CORRECT option is (a) SHORT-circuitedtwo winding transformer Explanation: For s=1 at standstill, so it same as the short CIRCUIT of the transformer for the INDUCTION MOTOR.

Discussion

81.	The leakage reactances are less than their values at the full load operating conditions. Why?(a) Due to large inrush current during starting(b) Due to very low saturation(c) Due to speed is not same as synchronous speed(d) All of the mentionedThis question was posed to me in final exam.My question comes from Equivalent Circuit topic in chapter Induction Machines of Electrical Machines
Answer» The correct choice is (a) Due to LARGE inrush current during starting The BEST I can explain: During the START, there will be large inrush currents FLOWING in the machine, which cause saturation and so the leakage reactance DECREASES at start.

Discussion

82.	The leakage reactance and the rotor resistance are constant throughout the operation in an induction motor.(a) True(b) FalseI got this question in quiz.My question comes from Equivalent Circuit in division Induction Machines of Electrical Machines
Answer» CORRECT OPTION is (b) False The BEST I can explain: No, the REACTANCE changes with the variation in the slip of the MACHINE.

Discussion

83.	The actual rotor resistance referred to the stator if the induction motor is?(a) r2(b) (r2)/s(c) (r2)/(1-s)(d) (r2)*(1-s)/sI got this question in unit test.My question is from Equivalent Circuit in chapter Induction Machines of Electrical Machines
Answer» Right CHOICE is (a) r2 Easiest EXPLANATION: The ACTUAL RESISTANCE will be r2 only.

Discussion

84.	The electrical anlogous of the mechanical load in the induction machine is given by?(a) (r2)*(1-s)/s(b) (r2)(c) (r2)/s(d) (r2)/(1-s)This question was addressed to me in semester exam.The doubt is from Equivalent Circuit in chapter Induction Machines of Electrical Machines
Answer» Right answer is (a) (r2)*(1-s)/s The explanation: MECHANICAL load is represented by a FACTOR (1-s)/s of the ROTOR resistance.

Discussion

85.	Rc in the below circuit represents?(a) core loss of induction motor(b) no load losses of induction motor(c) iron losses of induction motor(d) copper losses of induction motorThe question was asked in a job interview.Asked question is from Equivalent Circuit topic in division Induction Machines of Electrical Machines
Answer» The CORRECT OPTION is (a) CORE LOSS of induction motor Explanation: The shunt resistance will represent only the core loss of the induction motor.

Discussion

86.	If the operating voltage of the induction motor is increased by twice while keeping the frequency of the operation constant. Then the new starting torque will be?(a) 4T(b) 1/4T(c) T(d) 2*TThis question was addressed to me during an online exam.I'd like to ask this question from Induction Motor Phasor Diagram topic in division Induction Machines of Electrical Machines
Answer» RIGHT option is (a) 4T To explain I WOULD say: TST α V^2. T2/T1 = (2/1)^2 T2 = 4T1.

Discussion

87.	If the voltage and frequency of the induction machine is reduced to 50% of the operating region,the slip of the machine will be?(a) 2*s(b) s(c) 1/2s(d) 1/sThis question was addressed to me in final exam.This intriguing question originated from Induction Motor Phasor Diagram topic in division Induction Machines of Electrical Machines
Answer» The correct OPTION is (a) 2*s Best explanation: Slip α 1/f; EVEN THOUGH the FLUX remains constant as the v/f ratio is constant.

Discussion

88.	If the frequency is reduced by 50% for a 3-phase, 50 Hz induction motor having 4 poles. The slip at which the maximum torque occurs becomes _________(a) 2*s(b) s(c) 1/2s(d) 1/sI got this question in homework.Origin of the question is Induction Motor Phasor Diagram topic in division Induction Machines of Electrical Machines
Answer» CORRECT option is (a) 2*s The best explanation: s = r/x s α 1/f. If the FREQUENCY is reduced to half, SLIP INCREASES to TWICE.

Discussion

89.	If the voltage of a three phase induction motor if increased to 200%, then the slip if the machine changes to _________(a) 1/s(b) s(c) 1/2s(d) 2*sThis question was addressed to me during a job interview.The query is from Induction Motor Phasor Diagram in chapter Induction Machines of Electrical Machines
Answer» The CORRECT answer is (c) 1/2s The explanation: The SLIP will remain independent of the operating VOLTAGE.

Discussion

90.	A 3-phase induction motor had the maximum rated torque of 40 N-m while the load torque applied to it is 55 N-m.(a) The machine will become unstable(b) The machine will operate in stable region(c) The machine will get heated up(d) The machine will run at dangerously high speedThis question was posed to me in an online quiz.This interesting question is from Induction Motor Phasor Diagram in portion Induction Machines of Electrical Machines
Answer» Right choice is (a) The machine will BECOME unstable Explanation: Induction motor is unstable when the LOAD TORQUE is more the the maximum torque of the machine.

Discussion

91.	An induction motor X operating at the slip of 3%. An induction motor Y operating at slip of 40%.(a) Machine X is only stable(b) Machine Y is only stable(c) Both the machine X and Y are stable(d) Neither X nor Y is stableI have been asked this question in an interview.The doubt is from Induction Motor Phasor Diagram in section Induction Machines of Electrical Machines
Answer» RIGHT OPTION is (a) MACHINE X is only stable The best I can explain: Induction motor operates stable in the low SLIP regions as the losses are reduced.

Discussion

92.	The power input to the 3-phase induction motor is 60 kW. The stator losses total 1 kW. Find the mechanical power developed at the slip of 3%.(a) 57.23 kW(b) 58 kW(c) 56.8 kW(d) 59 kWThis question was posed to me during an online interview.My doubt stems from Induction Motor Phasor Diagram topic in section Induction Machines of Electrical Machines
Answer» Correct CHOICE is (a) 57.23 kW Best EXPLANATION: Air GAP power = 60-1 = 59 kW Pm = (1-s)PAG = 0.97*59 = 57.23 kW.

Discussion

93.	A 400, 3-phase, 50 Hz, 4 pole induction motor takes a line current of 10 A with 0.86 pf lagging. What is the stator input?(a) 5.95 kW(b) 6.95 kW(c) 4.45 kW(d) 8.38 kWThis question was addressed to me in an online interview.My query is from Induction Motor Phasor Diagram topic in portion Induction Machines of Electrical Machines
Answer» The correct answer is (a) 5.95 kW For EXPLANATION: P = 1.73VIcosθ = 1.73400100.86 = 5.958 kW.

Discussion

94.	Approximately the efficiency of the rotor of the induction motor depends on the _________(a) rotor speed(b) synchronous speed(c) rotor speed and synchronous speed(d) magnetic field speedThe question was posed to me during a job interview.This intriguing question originated from Induction Motor Phasor Diagram in section Induction Machines of Electrical Machines
Answer» The CORRECT OPTION is (c) rotor speed and SYNCHRONOUS speed Best explanation: Efficiency of the rotor is approximately EQUAL to ratio of speed of rotor to synchronous speed.

Discussion

95.	If the hysteresis is neglected in the induction machine, then the the air gap flux _______ the resultant mmf.(a) is in phase with(b) lags(c) leads by a small angle(d) can not decide the nature of the operationI got this question in unit test.This intriguing question originated from Induction Motor Phasor Diagram topic in portion Induction Machines of Electrical Machines
Answer» The correct answer is (a) is in phase with For explanation I WOULD SAY: When the hysteresis loss is neglected, then the AIR gap flux will be in phase with the RESULTANT mmf.

Discussion

96.	On increasing the starting torque of the induction motor, the maximum torque is also increased.(a) False(b) TrueThe question was asked during an internship interview.This intriguing question comes from Induction Motor Phasor Diagram in section Induction Machines of Electrical Machines
Answer» Correct CHOICE is (a) False To explain I WOULD SAY: It is false, as the starting torque and the maximum torque are independent of each other.

Discussion

97.	Rotor leakage impedance at starting is different from its value at normal running conditions.(a) True(b) FalseI had been asked this question in exam.The query is from Induction Motor Phasor Diagram topic in division Induction Machines of Electrical Machines
Answer» The CORRECT answer is (a) True Best EXPLANATION: The rotor LEAKAGE IMPEDANCE depends on the slip of the machine. Slip varies with the running conditions.

Discussion

98.	The rotor of the slip ring induction motor is connected to an ac source and stator is short circuited. If the rotating magnetic field is rotates clockwise, the rotor rotates in _________(a) anticlockwise(b) clockwise(c) remains stationary(d) any of the mentionedI had been asked this question in homework.Question is taken from Induction Motor Phasor Diagram in section Induction Machines of Electrical Machines
Answer» Correct OPTION is (a) anticlockwise Easiest explanation: ROTOR will ROTATE in anticlockwise DIRECTION as the net speed w.r.t. stator should be stationary.

Discussion

99.	If a 400 V, 50 hz star connected, 3-phase squirrel cage induction motor is operated from 400V and 75 Hz supply. The torque that the motor can now provide while drawing rated current from the supply will _________(a) reduce(b) increase(c) remains same(d) increases or reduces based on the rotor resistance.This question was posed to me by my college director while I was bunking the class.Origin of the question is Rotor EMF, Current and Power topic in portion Induction Machines of Electrical Machines
Answer» Correct OPTION is (a) reduce Explanation: The reactance will increase and so the TORQUE will DECREASE.

Discussion

100.	For a constant load torque, the supply voltage of a squirrel cage induction motor is reduced by a factor of 0.5, its rotor current is modified by a factor is?(a) 2(b) 0.5(c) 4(d) 0.25The question was posed to me in an interview for internship.The origin of the question is Rotor EMF, Current and Power in chapter Induction Machines of Electrical Machines
Answer» CORRECT choice is (a) 2 To explain: For constant TORQUE the product of emf and current should be constant.

Discussion

Explore topic-wise InterviewSolutions in .

The stable point in the operation of the induction motor is?(a) C(b) D(c) B(d) AI have been asked this question in a job interview.My question is based upon Operating (or Performance) Characteristics of Induction Motors in chapter Induction Machines of Electrical Machines

Developed torque during plugging is _________(a) negative(b) positive(c) zero(d) any of the mentionedI had been asked this question in examination.This intriguing question comes from Analysis of the Equivalent Circuit in section Induction Machines of Electrical Machines

Torque produced by induction generator is negative.(a) True(b) FalseI got this question during an interview for a job.I want to ask this question from Analysis of the Equivalent Circuit topic in division Induction Machines of Electrical Machines

Induction generators will deliver power at _________(a) leading p.f.(b) lagging p.f.(c) unity p.f.(d) zero p.f.I have been asked this question in class test.Question is from Equivalent Circuit in chapter Induction Machines of Electrical Machines

The leakage reactance and the rotor resistance are constant throughout the operation in an induction motor.(a) True(b) FalseI got this question in quiz.My question comes from Equivalent Circuit in division Induction Machines of Electrical Machines

The actual rotor resistance referred to the stator if the induction motor is?(a) r2(b) (r2)/s(c) (r2)/(1-s)(d) (r2)*(1-s)/sI got this question in unit test.My question is from Equivalent Circuit in chapter Induction Machines of Electrical Machines

The electrical anlogous of the mechanical load in the induction machine is given by?(a) (r2)*(1-s)/s(b) (r2)(c) (r2)/s(d) (r2)/(1-s)This question was addressed to me in semester exam.The doubt is from Equivalent Circuit in chapter Induction Machines of Electrical Machines

On increasing the starting torque of the induction motor, the maximum torque is also increased.(a) False(b) TrueThe question was asked during an internship interview.This intriguing question comes from Induction Motor Phasor Diagram in section Induction Machines of Electrical Machines

Rotor leakage impedance at starting is different from its value at normal running conditions.(a) True(b) FalseI had been asked this question in exam.The query is from Induction Motor Phasor Diagram topic in division Induction Machines of Electrical Machines