59 + Interview Questions in Introduction To Solid State Controlled Drives in Electric Drives Page 1 InterviewSolution

1.	Calculate the output voltage of the Buck-Boost converter if the supply voltage is 14 V and duty cycle value is .85.(a) 79.3 V(b) 45.5 V(c) 86.5 V(d) 54.7 VI got this question by my college director while I was bunking the class.I'd like to ask this question from Solid State Controlled Drives in portion Introduction to Solid State Controlled Drives of Electric Drives
Answer» Correct answer is (a) 79.3 V Explanation: The output voltage of the buck-boost converter is Vo = D×Vin ÷ (1-D)=.85(14)÷.15=79.3 V. It can STEP up and step down the voltage depending upon the value of the duty cycle. If the value of the duty cycle is less than .5 it will WORK as a buck converter and for duty cycle greater than .5 it will work as a boost converter.

Discussion

2.	Calculate the average inductor current of the Boost converter if the load current is 7 A and duty cycle value is .8.(a) 36 A(b) 35 A(c) 34 A(d) 31 AThe question was posed to me in my homework.Query is from Solid State Controlled Drives topic in portion Introduction to Solid State Controlled Drives of Electric Drives
Answer» The correct CHOICE is (B) 35 A The BEST explanation: The average inductor current of the Boost converter is Io÷(1-D)=7÷.2=35 A. The average value of the inductor current can be calculated using ampere-sec BALANCE METHOD.

Discussion

3.	Calculate the compensator rating required for cos(Φ)=.1.(a) 0.91 P.U(b) 0.99 P.U(c) 0.97 P.U(d) 0.92 P.UThe question was posed to me during an interview for a job.This question is from Solid State Controlled Drives in chapter Introduction to Solid State Controlled Drives of Electric Drives
Answer» Right ANSWER is (b) 0.99 P.U The best EXPLANATION: The compensator RATING can be calculated using the relation QP.U=√1-cos^2(∅)=√1-.01=.99. This per unit value VAR compensator is required to improve the power factor of the SYSTEM.

Discussion

4.	Calculate the output power of the Buck converter if the supply voltage is 4 V and duty cycle value is .1 for 4 Ω load.(a) 40 mW(b) 20 mW(c) 50 mW(d) 60 mWThis question was posed to me by my school principal while I was bunking the class.This key question is from Solid State Controlled Drives in portion Introduction to Solid State Controlled Drives of Electric Drives
Answer» The correct CHOICE is (a) 40 mW The EXPLANATION is: The output voltage of the buck converter is VO = Vin×(D)=.4. The value of the duty cycle is less than one which MAKES the Vo < Vin. The buck converter is used to step down the voltage. The output power is Vo^2÷R=40 mW.

Discussion

5.	In the biomedical instruments like artificial heart pumps, the motor used is ____________(a) DC shunt motor(b) DC series motor(c) Induction motor(d) BLDC motorI have been asked this question during an interview.My question is based upon Solid State Controlled Drives in portion Introduction to Solid State Controlled Drives of Electric Drives
Answer» CORRECT choice is (d) BLDC MOTOR For explanation: BLDC motors are widely USED in various applications of the medical industry. Sensorless BLDC motor and with sensor BLDC motors are used because of EASY operation and high reliability compare to conventional motors.

Discussion

6.	Calculate the value of Crest factor if Vpeak=141 V and Vr.m.s=100 V for sinusoidal voltage.(a) 1.41(b) 2.38(c) 4.42(d) 5.58This question was posed to me in final exam.My question comes from Solid State Controlled Drives topic in chapter Introduction to Solid State Controlled Drives of Electric Drives
Answer» The correct ANSWER is (a) 1.41 Explanation: The value of the crest FACTOR is Vpeak÷Vr.m.s=141÷100=1.41. It SIGNIFIES the PEAK value is 1.41 times than the r.m.s value.

Discussion

7.	Calculate peak-peak voltage if Vmax=45 V and Vmin=45 V.(a) 60 V(b) 30 V(c) 50 V(d) 0 VThe question was posed to me in a job interview.Enquiry is from Solid State Controlled Drives topic in chapter Introduction to Solid State Controlled Drives of Electric Drives
Answer» The correct CHOICE is (d) 0 V To elaborate: Peak-Peak voltage is equal to the difference between the maximum and MINIMUM voltage. It is mathematically represented as Vp-p=Vmax-Vmin=45-45=0 V. It signifies the signal is DC signal.

Discussion

8.	Which of the following are the types of BLDC motor?(a) Unipolar, Bipolar(b) Unipolar, PWM(c) Bipolar, PWM(d) Synchronous, InductionI have been asked this question in examination.My question is from Solid State Controlled Drives topic in chapter Introduction to Solid State Controlled Drives of Electric Drives
Answer» The correct answer is (a) Unipolar, Bipolar Easiest explanation: Unipolar and Bipolar are the TYPES of BLDC motor. They use the HALL effect rotor POSITION SENSOR and optical rotor position sensor.

Discussion

9.	Calculate the electrical angle for 6 pole machine. (θm represents mechanical angle)(a) 4×θm(b) 5×θm(c) 2×θm(d) 3×θmI got this question during an interview.The doubt is from Solid State Controlled Drives in portion Introduction to Solid State Controlled Drives of Electric Drives
Answer» RIGHT answer is (d) 3×θm Explanation: The electrical angle for 6 pole MACHINE is 3×θm. One electrical angle is equal to 180° MECHANICAL angle. θe=(P÷2)×θm.

Discussion

10.	Due to low inertia, BLDC motors have __________(a) Faster acceleration(b) Slower acceleration(c) High-cost(d) Low costThis question was addressed to me in an online quiz.Enquiry is from Solid State Controlled Drives topic in portion Introduction to Solid State Controlled Drives of Electric Drives
Answer» The CORRECT answer is (a) FASTER acceleration Easy explanation: Due to low inertia, BLDC motors have faster acceleration. BLDC motors have less weight. They can run at high SPEED than a conventional DC motor.

Discussion

11.	The speed of a BLDC motor can be controlled by __________(a) Changing input DC voltage(b) Changing temperature(c) Changing wind direction(d) Cannot be controlledI got this question in an international level competition.My question is from Solid State Controlled Drives in chapter Introduction to Solid State Controlled Drives of Electric Drives
Answer» The CORRECT ANSWER is (a) Changing input DC VOLTAGE To elaborate: The speed of a BLDC motor can be controlled by changing the input DC voltage or the current using PWM. It can be achievable by using a transistor and chopper.

Discussion

12.	BLDC motor is analogous to ______________(a) Permanent magnet synchronous motor(b) DC motor(c) Rotating Transformer(d) Single-phase Induction motorI have been asked this question during an interview.Asked question is from Solid State Controlled Drives in portion Introduction to Solid State Controlled Drives of Electric Drives
Answer» Right CHOICE is (a) Permanent MAGNET synchronous motor Explanation: BLDC motor is analogous to Permanent magnet synchronous motor. In BLDC motor armature windings are placed on the stator side. It is more economical and LESS maintenance is REQUIRED. Permanent magnets are placed on the ROTOR side.

Discussion

13.	In BLDC motor armature windings are placed on the stator side.(a) True(b) FalseI had been asked this question in an international level competition.My question is from Solid State Controlled Drives in chapter Introduction to Solid State Controlled Drives of Electric Drives
Answer» Correct choice is (a) True The explanation: In BLDC motor armature windings are placed on the stator SIDE. It is more economical and LESS maintenance is REQUIRED. Permanent MAGNETS are placed on the rotor side.

Discussion

14.	The Hall effect sensor is used as the rotor position sensor for the BLDC motor.(a) True(b) FalseI have been asked this question in unit test.The doubt is from Solid State Controlled Drives topic in section Introduction to Solid State Controlled Drives of Electric Drives
Answer» RIGHT choice is (a) True For explanation I would SAY: The Hall effect sensor is used as the rotor position sensor for the BLDC motor. It is used to measure the strength of the magnetic field.

Discussion

15.	Calculate the value of the frequency if the inductive reactance is 60 Ω and the value of the inductor is 4 H.(a) 2.38 Hz(b) 5.54 Hz(c) 4.65 Hz(d) 9.42 HzThe question was posed to me by my college director while I was bunking the class.I would like to ask this question from Solid State Controlled Drives in portion Introduction to Solid State Controlled Drives of Electric Drives
Answer» CORRECT CHOICE is (a) 2.38 Hz Explanation: The frequency is defined as the NUMBER of oscillations per second. The frequency can be calculated USING the relation XL = 2×3.14×f×L. F = XL÷2×3.14×L = 60÷2×3.14×4 = 2.38 Hz.

Discussion

16.	Calculate mark to space ratio if the system is on for 4 sec and off time is 9 sec.(a) .54(b) .44(c) .45(d) .46This question was posed to me by my college professor while I was bunking the class.My enquiry is from Solid State Controlled Drives in division Introduction to Solid State Controlled Drives of Electric Drives
Answer» The correct option is (b) .44 Explanation: MARK to SPACE is Ton÷Toff. It is the ratio of time for which the SYSTEM is active and the time for which is inactive. M = Ton÷Toff = 4÷(9) = .44.

Discussion

17.	Calculate the value of the duty cycle if the system is on for 1 sec and off for 17 sec.(a) .055(b) .781(c) .484(d) .947I got this question in an online quiz.Enquiry is from Solid State Controlled Drives topic in division Introduction to Solid State Controlled Drives of Electric Drives
Answer» The CORRECT answer is (a) .055 For explanation I WOULD say: Duty CYCLE is Ton÷Ttotal. It is the ratio of time for which the SYSTEM is active and the time TAKEN by the signal to complete one cycle. D = Ton÷Ttotal=1÷18=.055.

Discussion

18.	Calculate the reactive power in a 24.5 Ω resistor.(a) 0 VAR(b) 5 VAR(c) 8 VAR(d) 9 VARI have been asked this question in examination.My question is from Solid State Controlled Drives in division Introduction to Solid State Controlled Drives of Electric Drives
Answer» The correct answer is (a) 0 VAR Explanation: The RESISTOR is a linear element. It only absorbs REAL power and dissipates it in the form of heat. The voltage and current are in the same phase in case of the resistor so the ANGLE between V & I is 0°. Q = VIsin0 = 0 VAR.

Discussion

19.	Reluctance motor operates at power factor of __________(a) .8(b) .2(c) .3(d) .9I had been asked this question during an online interview.My doubt is from Solid State Controlled Drives in division Introduction to Solid State Controlled Drives of Electric Drives
Answer» The correct choice is (a) .8 Easiest EXPLANATION: Reluctance motor OPERATES at a power FACTOR of .8. The Reluctance motor works on the principle of an Induction motor.

Discussion

20.	Calculate the value of Crest factor if Vpeak=798 V and Vr.m.s=489 V.(a) 1.63(b) 1.54(c) 1.59(d) 1.26This question was posed to me by my school principal while I was bunking the class.My query is from Solid State Controlled Drives in portion Introduction to Solid State Controlled Drives of Electric Drives
Answer» The correct ANSWER is (a) 1.63 The explanation is: The VALUE of the CREST FACTOR is Vpeak÷Vr.m.s=798÷489=1.63 V. It SIGNIFIES the peak value is 1.63 times than the r.m.s value.

Discussion

21.	Calculate peak-peak voltage if Vmax=180 V and Vmin=60 V.(a) 120 V(b) 150 V(c) 170 V(d) 110 VI have been asked this question by my school principal while I was bunking the class.This is a very interesting question from Solid State Controlled Drives topic in section Introduction to Solid State Controlled Drives of Electric Drives
Answer» The correct ANSWER is (a) 120 V The explanation: Peak-Peak VOLTAGE is EQUAL to the difference between the maximum and minimum voltage. It is mathematically represented as Vp-p=Vmax-Vmin=180-60=120 V.

Discussion

22.	Calculate the circuit turn-off time for 3-Φ Fully controlled rectifier if the firing angle is 120° and supply frequency is 60 Hz.(a) 1.8 msec(b) 3.2 msec(c) 6.3 msec(d) 2.7 msecThis question was posed to me in class test.The query is from Solid State Controlled Drives in chapter Introduction to Solid State Controlled Drives of Electric Drives
Answer» Correct choice is (d) 2.7 msec To ELABORATE: The circuit turn-off TIME for 3-Φ Fully controlled RECTIFIER is (180°-α)÷ω. The VALUE of circuit turn-off time for ∝ ≥ 60° is (180°-120°)÷6.28×60=2.7 msec.

Discussion

23.	Calculate the circuit turn-off time for 3-Φ Fully controlled rectifier if the firing angle is 27° and supply frequency is 50 Hz.(a) 11.8 msec(b) 14.4 msec(c) 16.1 msec(d) 16.5 msecThe question was asked during an interview.I'm obligated to ask this question of Solid State Controlled Drives in section Introduction to Solid State Controlled Drives of Electric Drives
Answer» The correct answer is (a) 11.8 msec To ELABORATE: The CIRCUIT turn-off TIME for 3-Φ Fully CONTROLLED rectifier is (240°-α)÷ω. The VALUE of circuit turn-off time for ∝ < 60° is (240°-27°)÷6.28×50=11.8 msec.

Discussion

24.	Increasing the stator poles ___________ the speed of Reluctance motor.(a) Decreases(b) Increases(c) Remains the same(d) NegativeThe question was posed to me in an internship interview.The query is from Solid State Controlled Drives topic in section Introduction to Solid State Controlled Drives of Electric Drives
Answer» The correct option is (a) Decreases The BEST I can EXPLAIN: INCREASING the stator POLES decreases the speed of Reluctance motor. The rotating magnetic field is DEVELOPED which rotates at the speed of Ns . Ns∝(1÷P).

Discussion

25.	Reluctance motor can operate on DC supply.(a) True(b) FalseThe question was asked during a job interview.Asked question is from Solid State Controlled Drives topic in portion Introduction to Solid State Controlled Drives of Electric Drives
Answer» Correct choice is (a) True The explanation is: Reluctance motor can OPERATE on AC SUPPLY. It cannot operate on DC supply. Reluctance MOTORS are singly-excited.

Discussion

26.	Which of the following motor is used in recording instruments?(a) Reluctance motor(b) Induction motor(c) Synchronous motor(d) DC motorI have been asked this question in unit test.My question is from Solid State Controlled Drives in chapter Introduction to Solid State Controlled Drives of Electric Drives
Answer» Right answer is (a) Reluctance MOTOR The EXPLANATION is: Reluctance motor is USED in recording instruments. It is used for many CONSTANT speed applications. The starting torque of the motor depends upon the rotor POSITION.

Discussion

27.	Calculate the value of the Input power factor for 3-Φ Fully controlled rectifier if the firing angle value is 90°.(a) 0(b) .2(c) .3(d) .4The question was posed to me in an interview for job.My doubt stems from Solid State Controlled Drives topic in section Introduction to Solid State Controlled Drives of Electric Drives
Answer» The correct option is (a) 0 Easiest explanation: The value of the INPUT power FACTOR for 3-Φ FULLY controlled rectifier is .95cos(90°)=0. The input power factor is a product of distortion factor and displacement factor.

Discussion

28.	An infinite bus-bar has _____________(a) Constant voltage(b) Constant frequency(c) Constant voltage and frequency(d) constant speedI got this question in an international level competition.Origin of the question is Solid State Controlled Drives topic in portion Introduction to Solid State Controlled Drives of Electric Drives
Answer» Correct answer is (C) Constant voltage and frequency To EXPLAIN I would say: An infinite bus-bar has constant voltage and constant speed. It has many TYPES like single bus-bar, DOUBLE bus-bar. It is connected to the GRID.

Discussion

29.	Reluctance motors are singly-excited.(a) True(b) FalseI had been asked this question in a job interview.This question is from Solid State Controlled Drives topic in division Introduction to Solid State Controlled Drives of Electric Drives
Answer» Correct answer is (a) True For explanation I would SAY: Reluctance MOTORS are singly-excited. Stator SIDE of the motor is excited by an AC source. Due to excitation, a revolving magnetic field is a CREATED and ROTOR rotates with the synchronous speed.

Discussion

30.	The unit of angular acceleration is Joule.(a) True(b) FalseI had been asked this question in an online interview.My enquiry is from Solid State Controlled Drives topic in chapter Introduction to Solid State Controlled Drives of Electric Drives
Answer» Right ANSWER is (b) False To elaborate: Angular acceleration is DEFINED as a DERIVATE of angular velocity with respect to time. It is GENERALLY WRITTEN as α. The unit of angular velocity is rad/sec and of time is second so the unit of angular acceleration is rad/s^2.

Discussion

31.	The principle of Boost converter can be applied for the regenerative braking.(a) True(b) FalseI have been asked this question during an interview.This intriguing question originated from Solid State Controlled Drives in portion Introduction to Solid State Controlled Drives of Electric Drives
Answer» The correct option is (a) True To explain: The Buck converter is USED in MOTORING mode but a Boost converter can operate only BRAKING mode because the characteristics are in the SECOND quadrant only.

Discussion

32.	Calculate the output voltage of the Buck-Boost converter if the supply voltage is 78 V and duty cycle value is .1.(a) 7.2 V(b) 4.5 V(c) 8.6 V(d) 5.1 VI have been asked this question in a national level competition.Question is taken from Solid State Controlled Drives topic in chapter Introduction to Solid State Controlled Drives of Electric Drives
Answer» Right choice is (c) 8.6 V Explanation: The output voltage of the buck-BOOST converter is Vo = D×Vin ÷ (1-D)=.1(78)÷.9=8.6 V. It can step up and step down the voltage depending upon the VALUE of the duty cycle. If the value of the duty cycle is LESS than .5 it will work as a buck converter and for duty cycle greater than .5 it will work as a boost converter.

Discussion

33.	Calculate the output voltage of the Boost converter if the supply voltage is 8 V and duty cycle value is .6.(a) 40 V(b) 20 V(c) 48 V(d) 51 VI have been asked this question in an online interview.My question is from Solid State Controlled Drives topic in chapter Introduction to Solid State Controlled Drives of Electric Drives
Answer» Correct answer is (b) 20 V To explain: The output voltage of the boost converter is Vo = VIN ÷ (1-D) = 8÷.4 = 20 V. The value of the duty cycle is less than ONE which makes the Vo > Vin as denominator value decreases and becomes less than one. The boost converter is used to STEP up the voltage.

Discussion

34.	Calculate the output voltage of the Buck converter if the supply voltage is 11 V and duty cycle value is .4.(a) 4.4 V(b) 2.2 V(c) 4.8 V(d) 6.4 VThe question was asked during an online exam.Question is from Solid State Controlled Drives in division Introduction to Solid State Controlled Drives of Electric Drives
Answer» Correct ANSWER is (a) 4.4 V The explanation: The output voltage of the buck converter is Vo = Vin×(D)=11×.4=4.4 V. The VALUE of the DUTY cycle is less than one which MAKES the Vo < Vin. The buck converter is used to step down the voltage.

Discussion

35.	Calculate the value of Crest factor if Vpeak=12 V and Vr.m.s=24 V.(a) .2(b) .3(c) .4(d) .5I have been asked this question at a job interview.My question is taken from Solid State Controlled Drives topic in portion Introduction to Solid State Controlled Drives of Electric Drives
Answer» Right OPTION is (d) .5 For explanation I would say: The value of the CREST factor is Vpeak÷Vr.m.s=12÷24=.5. It SIGNIFIES the peak value is .5 TIMES than the r.m.s value.

Discussion

36.	Calculate peak-peak voltage if Vmax=80 V and Vmin=20 V.(a) 60 V(b) 50 V(c) 70 V(d) 10 VThe question was posed to me during an online exam.The doubt is from Solid State Controlled Drives topic in chapter Introduction to Solid State Controlled Drives of Electric Drives
Answer» Correct option is (a) 60 V Easy EXPLANATION: Peak-Peak VOLTAGE is equal to the difference between the maximum and MINIMUM voltage. It is mathematically represented as Vp-p=Vmax-Vmin=80-20=60 V.

Discussion

37.	Calculate the circuit turn-off time for 3-Φ Fully controlled rectifier if the firing angle is 110° and supply frequency is 50 Hz.(a) 3.8 msec(b) 5.2 msec(c) 9.3 msec(d) 8.7 msecI got this question in a national level competition.I'd like to ask this question from Solid State Controlled Drives in portion Introduction to Solid State Controlled Drives of Electric Drives
Answer» CORRECT choice is (a) 3.8 msec Best explanation: The CIRCUIT turn-off TIME for 3-Φ Fully CONTROLLED rectifier is (180°-α)÷ω;. The value of circuit turn-off time for ∝ ≥ 60° is (180°-110°)÷6.28×50=3.8 msec.

Discussion

38.	Calculate the circuit turn-off time for 3-Φ Fully controlled rectifier if the firing angle is 20° and supply frequency is 60 Hz.(a) 8.8 msec(b) 7.4 msec(c) 10.1 msec(d) 6.5 msecThis question was posed to me in exam.The question is from Solid State Controlled Drives topic in chapter Introduction to Solid State Controlled Drives of Electric Drives
Answer» Right option is (C) 10.1 msec To EXPLAIN I would say: The CIRCUIT turn-off time for 3-Φ FULLY controlled rectifier is (240°-α)÷ω. The VALUE of circuit turn-off time for ∝ < 60° is (240°-20°)÷6.28×60=10.1 msec.

Discussion

39.	In 3-Φ Semi-controlled rectifier calculate the average value of the voltage if the supply is 440 V and firing angle is 22°.(a) 571.5 V(b) 572.8 V(c) 548.3 V(d) 524.1 VI have been asked this question by my college professor while I was bunking the class.This intriguing question comes from Solid State Controlled Drives in division Introduction to Solid State Controlled Drives of Electric Drives
Answer» Right option is (B) 572.8 V To explain: In 3-Φ Semi-controlled RECTIFIER, the average value of the VOLTAGE is 3Vml(1+cos(∝))÷2π=3×440×√2(1+cos(22°))÷6.28=572.8 V.

Discussion

40.	Calculate the value of THD value for 3-Φ Fully controlled rectifier.(a) 48.43 %(b) 47.25 %(c) 39.26 %(d) 31 %I have been asked this question during an online interview.Enquiry is from Solid State Controlled Drives topic in portion Introduction to Solid State Controlled Drives of Electric Drives
Answer» Right option is (d) 31 % Explanation: The VALUE of the distortion factor is .95. The value of THD value for 3-Φ FULLY CONTROLLED rectifier is √(1÷.95)^2-1=31 %. THD measures the amount of HARMONIC distortion.

Discussion

41.	Calculate the value of the Input power factor for 3-Φ Fully controlled rectifier if the firing angle value is 70°.(a) .32(b) .38(c) .31(d) .33I got this question at a job interview.This interesting question is from Solid State Controlled Drives in section Introduction to Solid State Controlled Drives of Electric Drives
Answer» The correct answer is (a) .32 Best EXPLANATION: The value of the input POWER factor for 3-Φ Fully controlled RECTIFIER is .95cos(70°)=.32. The input power factor is a product of DISTORTION factor and displacement factor.

Discussion

42.	In 3-Φ Fully controlled rectifier calculate the average value of the voltage if the supply is 400 V and firing angle is 15°.(a) 521.2 V(b) 522 V(c) 523 V(d) 524 VThe question was asked in class test.The above asked question is from Solid State Controlled Drives topic in section Introduction to Solid State Controlled Drives of Electric Drives
Answer» CORRECT answer is (B) 522 V Explanation: In 3-Φ Fully controlled RECTIFIER, the average value of the VOLTAGE is 3Vml(cos(∝))÷π=3×400×√2(cos(15°))÷3.14=522 V.

Discussion

43.	Calculate the pulse number if the supply frequency is 2π and the output frequency is π÷3.(a) 4(b) 2(c) 6(d) 8I had been asked this question in an interview.Enquiry is from Solid State Controlled Drives in division Introduction to Solid State Controlled Drives of Electric Drives
Answer» Correct choice is (C) 6 Explanation: The pulse NUMBER can be calculated using the RATIO of input frequency to the output frequency. The value of pulse number (P) is 2π÷π÷3=6. It is a six-pulse CONVERTER.

Discussion

44.	Calculate the output frequency for the two-pulse converter if the supply frequency is 20 Hz.(a) 40 Hz(b) 20 Hz(c) 60 Hz(d) 90 HzI had been asked this question by my school teacher while I was bunking the class.Question is taken from Solid State Controlled Drives in chapter Introduction to Solid State Controlled Drives of Electric Drives
Answer» Right option is (a) 40 Hz Easy EXPLANATION: The OUTPUT of a TWO-pulse converter consists of two PULSES in one cycle. The output frequency of the two pulse converter is 2×supply frequency=2×20=40 Hz.

Discussion

45.	Calculate the value of the fundamental displacement factor for 1-Φ Full wave semi-converter if the firing angle value is 20°.(a) .82(b) .98(c) .74(d) .26I got this question during an interview.My question comes from Solid State Controlled Drives topic in chapter Introduction to Solid State Controlled Drives of Electric Drives
Answer» The CORRECT CHOICE is (b) .98 Explanation: Fundamental displacement factor is the cosine of ANGLE DIFFERENCE between the fundamental voltage and fundamental current. The fundamental displacement factor for 1-Φ FULL wave semi-converter is cos(∝÷2)=cos(10°)=.98.

Discussion

46.	Calculate the value of the fundamental displacement factor for 1-Φ Full wave bridge rectifier if the firing angle value is 60°.(a) .5(b) .4(c) .2(d) .8I had been asked this question in final exam.My query is from Solid State Controlled Drives topic in chapter Introduction to Solid State Controlled Drives of Electric Drives
Answer» Right OPTION is (a) .5 The explanation is: Fundamental DISPLACEMENT factor is the COSINE of angle DIFFERENCE between the fundamental voltage and fundamental current. D.F=cos(∝)=cos(60°)=0.5.

Discussion

47.	Calculate the value of the Input power factor for 1-Φ Full wave bridge rectifier if the firing angle value is 45°.(a) .65(b) .64(c) .61(d) .63This question was posed to me during a job interview.My enquiry is from Solid State Controlled Drives in chapter Introduction to Solid State Controlled Drives of Electric Drives
Answer» Correct choice is (d) .63 For EXPLANATION: The value of the input POWER FACTOR for 1-Φ Full WAVE bridge rectifier is .9cos(45°)=.63. The input power factor is a product of distortion factor and displacement factor.

Discussion

48.	Calculate the value of THD value for 1-Φ Full wave bridge rectifier.(a) 48.43 %(b) 47.25 %(c) 49.26 %(d) 50.48 %I got this question in final exam.My question is taken from Solid State Controlled Drives topic in chapter Introduction to Solid State Controlled Drives of Electric Drives
Answer» Right option is (a) 48.43 % Easiest EXPLANATION: The value of the DISTORTION FACTOR is .9. The value of THD value for 1-Φ Full wave bridge rectifier is √(1÷.9)^2-1=48.43 %. THD measures the amount of harmonic distortion.

Discussion

49.	Calculate the r.m.s value of the current through the thyristor in case of 1-Φ Full wave bridge rectifier if the value of the load current is 2 A.(a) 1.414 A(b) 1.214 A(c) 1.347 A(d) 1.657 AThe question was posed to me in examination.My enquiry is from Solid State Controlled Drives topic in division Introduction to Solid State Controlled Drives of Electric Drives
Answer» Correct CHOICE is (a) 1.414 A Easy EXPLANATION: The r.m.s value of the current through the thyristor in case of 1-∅ full WAVE bridge RECTIFIER is Io÷√2=√2 A=1.414 A. Each thyristor conducts for 180°.

Discussion

50.	Calculate the average value of the current through the thyristor in case of 1-Φ Full wave bridge rectifier if the value of the load current is 42 A.(a) 21 A(b) 12 A(c) 14 A(d) 16 AI had been asked this question in an online quiz.I need to ask this question from Solid State Controlled Drives topic in portion Introduction to Solid State Controlled Drives of Electric Drives
Answer» Correct answer is (a) 21 A For explanation: The average value of the CURRENT through the THYRISTOR in case of 1-∅ full wave BRIDGE rectifier is Io÷2=21 A. Each thyristor CONDUCTS for 180°.

Discussion

Explore topic-wise InterviewSolutions in .

Calculate the compensator rating required for cos(Φ)=.1.(a) 0.91 P.U(b) 0.99 P.U(c) 0.97 P.U(d) 0.92 P.UThe question was posed to me during an interview for a job.This question is from Solid State Controlled Drives in chapter Introduction to Solid State Controlled Drives of Electric Drives

Calculate peak-peak voltage if Vmax=45 V and Vmin=45 V.(a) 60 V(b) 30 V(c) 50 V(d) 0 VThe question was posed to me in a job interview.Enquiry is from Solid State Controlled Drives topic in chapter Introduction to Solid State Controlled Drives of Electric Drives

Calculate the electrical angle for 6 pole machine. (θm represents mechanical angle)(a) 4×θm(b) 5×θm(c) 2×θm(d) 3×θmI got this question during an interview.The doubt is from Solid State Controlled Drives in portion Introduction to Solid State Controlled Drives of Electric Drives

Due to low inertia, BLDC motors have __________(a) Faster acceleration(b) Slower acceleration(c) High-cost(d) Low costThis question was addressed to me in an online quiz.Enquiry is from Solid State Controlled Drives topic in portion Introduction to Solid State Controlled Drives of Electric Drives

In BLDC motor armature windings are placed on the stator side.(a) True(b) FalseI had been asked this question in an international level competition.My question is from Solid State Controlled Drives in chapter Introduction to Solid State Controlled Drives of Electric Drives

The Hall effect sensor is used as the rotor position sensor for the BLDC motor.(a) True(b) FalseI have been asked this question in unit test.The doubt is from Solid State Controlled Drives topic in section Introduction to Solid State Controlled Drives of Electric Drives

Calculate the value of the duty cycle if the system is on for 1 sec and off for 17 sec.(a) .055(b) .781(c) .484(d) .947I got this question in an online quiz.Enquiry is from Solid State Controlled Drives topic in division Introduction to Solid State Controlled Drives of Electric Drives

Calculate the reactive power in a 24.5 Ω resistor.(a) 0 VAR(b) 5 VAR(c) 8 VAR(d) 9 VARI have been asked this question in examination.My question is from Solid State Controlled Drives in division Introduction to Solid State Controlled Drives of Electric Drives

Reluctance motor operates at power factor of __________(a) .8(b) .2(c) .3(d) .9I had been asked this question during an online interview.My doubt is from Solid State Controlled Drives in division Introduction to Solid State Controlled Drives of Electric Drives

Reluctance motor can operate on DC supply.(a) True(b) FalseThe question was asked during a job interview.Asked question is from Solid State Controlled Drives topic in portion Introduction to Solid State Controlled Drives of Electric Drives

Reluctance motors are singly-excited.(a) True(b) FalseI had been asked this question in a job interview.This question is from Solid State Controlled Drives topic in division Introduction to Solid State Controlled Drives of Electric Drives

The unit of angular acceleration is Joule.(a) True(b) FalseI had been asked this question in an online interview.My enquiry is from Solid State Controlled Drives topic in chapter Introduction to Solid State Controlled Drives of Electric Drives

The principle of Boost converter can be applied for the regenerative braking.(a) True(b) FalseI have been asked this question during an interview.This intriguing question originated from Solid State Controlled Drives in portion Introduction to Solid State Controlled Drives of Electric Drives

Calculate the value of Crest factor if Vpeak=12 V and Vr.m.s=24 V.(a) .2(b) .3(c) .4(d) .5I have been asked this question at a job interview.My question is taken from Solid State Controlled Drives topic in portion Introduction to Solid State Controlled Drives of Electric Drives

Calculate peak-peak voltage if Vmax=80 V and Vmin=20 V.(a) 60 V(b) 50 V(c) 70 V(d) 10 VThe question was posed to me during an online exam.The doubt is from Solid State Controlled Drives topic in chapter Introduction to Solid State Controlled Drives of Electric Drives

Calculate the value of THD value for 3-Φ Fully controlled rectifier.(a) 48.43 %(b) 47.25 %(c) 39.26 %(d) 31 %I have been asked this question during an online interview.Enquiry is from Solid State Controlled Drives topic in portion Introduction to Solid State Controlled Drives of Electric Drives

Calculate the pulse number if the supply frequency is 2π and the output frequency is π÷3.(a) 4(b) 2(c) 6(d) 8I had been asked this question in an interview.Enquiry is from Solid State Controlled Drives in division Introduction to Solid State Controlled Drives of Electric Drives

Calculate the value of THD value for 1-Φ Full wave bridge rectifier.(a) 48.43 %(b) 47.25 %(c) 49.26 %(d) 50.48 %I got this question in final exam.My question is taken from Solid State Controlled Drives topic in chapter Introduction to Solid State Controlled Drives of Electric Drives