MCQOPTIONS
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MCQOPTIONS
This section includes 69 Mcqs, each offering curated multiple-choice questions to sharpen your Electrical Engineering Questions knowledge and support exam preparation. Choose a topic below to get started.
| 1. |
With gate open, the maximum anode current at which SCR is turned off from ON condition is called |
| A. | breakdown voltage |
| B. | peak reverse voltage |
| C. | holding current |
| D. | latching current |
| Answer» D. latching current | |
| 2. |
Voltage commutation circuit can be converted into a current commutation by interchanging the positions of |
| A. | Diode and capacitor |
| B. | Capacitor and SCR |
| C. | Inductor and capacitor |
| D. | Capacitor and load |
| Answer» B. Capacitor and SCR | |
| 3. |
TRIAC is a semiconductor power electronic device which contains |
| A. | Two SCR’s connected in reverse parallel |
| B. | Two SCR’s connected in parallel |
| C. | Two SCR’s connected in series |
| D. | Two BJT’s connected in series |
| Answer» B. Two SCR’s connected in parallel | |
| 4. |
Transformer utilization factor is a measure of the merit of a rectifier circuit. It is the ratio of |
| A. | AC input power to the transformer volt - amp rating required by secondary |
| B. | AC input power to the transformer volt - amp rating required by primary |
| C. | DC output power to the transformer volt - amp rating required by secondary |
| D. | DC output power to the transformer volt - amp rating required by primary |
| Answer» D. DC output power to the transformer volt - amp rating required by primary | |
| 5. |
To detect an over - current fault condition, the most reliable method is to connect a |
| A. | Current sensor across IGBT |
| B. | Voltage sensor across IGBT |
| C. | Current sensor in series with IGBT |
| D. | Voltage sensor in series with IGBT |
| Answer» D. Voltage sensor in series with IGBT | |
| 6. |
The transfer function of PWM is generally developed in |
| A. | Time domain |
| B. | Frequency domain |
| C. | Either (a) or (b) |
| D. | None of these |
| Answer» D. None of these | |
| 7. |
The switching function of semiconductor devices can be characterized with |
| A. | Duty ratio only |
| B. | Frequency only |
| C. | Duty ratio and frequency |
| D. | Duty ratio, frequency and time delay |
| Answer» E. | |
| 8. |
The sum of all phase current in a star connected primary winding with no neutral connection is equal to |
| A. | Phase current |
| B. | Three times the phase current |
| C. | Three times the line current |
| D. | Zero at all times |
| Answer» E. | |
| 9. |
The square wave operation of 3 phase VSI lines contains the harmonics. The amplitudes are |
| A. | Directly proportional to their harmonic order |
| B. | Inversely proportional to their harmonic order |
| C. | Not related to their harmonic order |
| D. | None of these |
| Answer» C. Not related to their harmonic order | |
| 10. |
The phase angle of gate signal in TRIAC can be shifted by using |
| A. | A capacitor |
| B. | A variable resistor |
| C. | An inductor |
| D. | Only (a) and (b) |
| Answer» E. | |
| 11. |
The output power of the cascaded amplifier / attenuator system can be determined using |
| A. | Actual gain of amplifier |
| B. | Actual gain of amplifier and attenuator |
| C. | Gain in dB of amplifier and attenuator |
| D. | Actual gain of attenuator |
| Answer» C. Gain in dB of amplifier and attenuator | |
| 12. |
The opposite of susceptibility is |
| A. | Immunity |
| B. | Emission |
| C. | Interference |
| D. | Electromagnetic compatibility |
| Answer» B. Emission | |
| 13. |
The most suited gate pulses given to the AC regulator with R - L load can be in the form of |
| A. | Continuous signal |
| B. | Large isolating pulse transformer |
| C. | A train of pulses |
| D. | None of these |
| Answer» D. None of these | |
| 14. |
The man made noise sources is / are |
| A. | Motors |
| B. | Switches, radio interferences |
| C. | Computers, digital electronics |
| D. | All of these |
| Answer» E. | |
| 15. |
The main objective of static power converters is to |
| A. | Obtain an dc output waveform from a dc power supply |
| B. | Obtain an ac output waveform from a dc power supply |
| C. | Obtain an dc output waveform from a dc power supply |
| D. | Obtain an ac output waveform from a ac power supply |
| Answer» C. Obtain an dc output waveform from a dc power supply | |
| 16. |
The input current waveform of a bridge controlled rectifier when the load is perfectly filtered is |
| A. | Sine wave |
| B. | Square wave |
| C. | Saw - tooth wave |
| D. | Trapezoidal wave |
| Answer» C. Saw - tooth wave | |
| 17. |
The IGBT resulted in higher switching speed and lower energy losses. It can be used for |
| A. | Uninterruptible power supplies |
| B. | Induction heating system |
| C. | Constant voltage and frequency power supplies |
| D. | All of these |
| Answer» E. | |
| 18. |
The Graetz bridge makes excellent use of |
| A. | Current transformer |
| B. | Potential transformer |
| C. | Power transformer |
| D. | SCR |
| Answer» D. SCR | |
| 19. |
The effects of EMI can be reduced by |
| A. | Suppressing emissions |
| B. | Reducing the efficiency of the coupling path |
| C. | Reducing the susceptibility of the receptor |
| D. | All of these |
| Answer» E. | |
| 20. |
The curve between V and I of SCR when anode is positive w.r.t cathode and when anode is negative w.r.t cathode are known as |
| A. | both as forward characteristics |
| B. | both as reverse characteristics |
| C. | former as forward characteristics and later as reverse characteristics |
| D. | former as reverse characteristics and later as forward characteristics |
| Answer» D. former as reverse characteristics and later as forward characteristics | |
| 21. |
The conduction losses in IGBT is |
| A. | More than that of MOSFET |
| B. | Lower than that of MOSFET |
| C. | Equal to that of MOSFET |
| D. | Equal to that of BJT |
| Answer» C. Equal to that of MOSFET | |
| 22. |
The carrier which are commonly used in constant - frequency PWM is |
| A. | Sawtooth carrier |
| B. | Inverted sawtooth carrier |
| C. | Triangle carrier |
| D. | All of these |
| Answer» E. | |
| 23. |
The advantage of using free - wheeling diode in half controlled bridge converter is that |
| A. | There is always a path for the dc current independent of the ac line |
| B. | There is always a path for the ac current independent of the ac line |
| C. | There is always a path for the dc current dependent of the ac line |
| D. | There is always a path for the ac current independent of the ac line |
| Answer» B. There is always a path for the ac current independent of the ac line | |
| 24. |
The ac voltage controller can be used for |
| A. | Lighting and heating control |
| B. | On - line transformer tap changing |
| C. | Soft starting |
| D. | All of these |
| Answer» E. | |
| 25. |
The ac output voltage waveform of VSI and AC output current waveform of CSI respectively is composed of |
| A. | High dv / dt, low di / dt |
| B. | Low dv / dt, low di / dt |
| C. | Low dv / dt, high di / dt |
| D. | High dv / dt, high di / dt |
| Answer» E. | |
| 26. |
Regulator sampling PWM is usually used in |
| A. | High power inverters |
| B. | Rectifiers |
| C. | Low power inverters |
| D. | Only (a) and (b) |
| Answer» E. | |
| 27. |
MOSFET stands for |
| A. | Metal - oxide semiconductor field effect transistor |
| B. | Molybdenum - oxide semiconductor field effect transistor |
| C. | Metal - oxide silicon field effect transistor |
| D. | Metal - oxide semiconductor field effect transmitter |
| Answer» B. Molybdenum - oxide semiconductor field effect transistor | |
| 28. |
LISN is a device used to measure conducted emissions. LISN stands for |
| A. | Line integrated stabilization network |
| B. | Line impedance stabilization network |
| C. | Line integrated stored network |
| D. | Laser integrated stabilization networking |
| Answer» C. Line integrated stored network | |
| 29. |
In variable frequency, PWM gain |
| A. | Phase lead helps to increase the phase margin of the control loop |
| B. | Phase lag helps to increase the phase margin of the control loop |
| C. | Phase lead helps to decrease the phase margin of the control loop |
| D. | Phase lag helps to decrease the phase margin of the control loop |
| Answer» B. Phase lag helps to increase the phase margin of the control loop | |
| 30. |
In the SPWM, the modulating signal is |
| A. | Square |
| B. | Sinusoidal |
| C. | Triangular |
| D. | Saw - tooth |
| Answer» C. Triangular | |
| 31. |
In the operation and control of both naturally commutated and forced commutated SCR base converter, commutation plays an important role. The converters is / are |
| A. | AC - DC |
| B. | DC - DC |
| C. | DC - AC |
| D. | All of these |
| Answer» E. | |
| 32. |
In square wave operation mode of 3 phase VSI, the VSI |
| A. | Can control the load voltage |
| B. | Cannot control the load voltage |
| C. | Cannot control the load voltage except by means of dc link voltage |
| D. | Cannot control the load voltage except by means of dc link current |
| Answer» D. Cannot control the load voltage except by means of dc link current | |
| 33. |
In single phase VSI, the harmonic which is not present is |
| A. | 2nd |
| B. | 3rd |
| C. | 5th |
| D. | 7th |
| Answer» B. 3rd | |
| 34. |
In rectifiers, load current flow is |
| A. | Unidirectional |
| B. | Bidirectional |
| C. | Either (a) or (b) |
| D. | Non directional |
| Answer» B. Bidirectional | |
| 35. |
In radiative coupling, the emitter radiation field |
| A. | Decays as 1 / R, where R is the separation distance between the emitter and the receptor |
| B. | Decays as R, where R is the separation distance between the emitter and the receptor |
| C. | Decays as 1 / 2 R, where R is the separation distance between the emitter and the receptor |
| D. | Decays as 2R, where R is the separation distance between the emitter and the receptor |
| Answer» B. Decays as R, where R is the separation distance between the emitter and the receptor | |
| 36. |
In EMC signal, the source delivers maximum power to the input of transmission line when the transmission line input impedance |
| A. | Is equal to the source resistance |
| B. | Greater than the source resistance |
| C. | Smaller than the source resistance |
| D. | None of these |
| Answer» B. Greater than the source resistance | |
| 37. |
In current commutated DC-DC choppers, the voltage spike appears across the load when |
| A. | Voltage across the commutating inductances collapses |
| B. | The capacitance voltage adds to the supply voltage |
| C. | Both (a) and (b) |
| D. | None of these |
| Answer» D. None of these | |
| 38. |
In constant frequency PWM, at perturbation the amplitude of the sinusoidal component is a |
| A. | Linear function |
| B. | Non linear function |
| C. | Constant function |
| D. | None of these |
| Answer» E. | |
| 39. |
In commutation PAC stands for |
| A. | Permanent angle converter |
| B. | Phase angle converter |
| C. | Phase angle commutation |
| D. | Phase and commutation |
| Answer» C. Phase angle commutation | |
| 40. |
In BJT, the forward biased base emitter junction inject holes from base to emitter, the holes |
| A. | Do not contribute to the collector current |
| B. | Result in net current flow component into the base |
| C. | Contribute to the collector current |
| D. | Only (a) and (b) |
| E. | Only (b) and (c) |
| Answer» E. Only (b) and (c) | |
| 41. |
In ac - dc conversion, when the switch is closed then the sum of voltages around the loop is |
| A. | Zero |
| B. | Non zero |
| C. | Equal to the sum of voltage when switch is open |
| D. | Twice of the voltage when switch is open |
| Answer» C. Equal to the sum of voltage when switch is open | |
| 42. |
In a three phase voltage source inverters |
| A. | Only amplitude of voltage is controllable |
| B. | Only phase is controllable |
| C. | Both amplitude and phase is controllable |
| D. | Amplitude, phase and frequency of voltages should always be controllable |
| Answer» E. | |
| 43. |
In a square - wave operation of 3 phase CSIs, the power values are on for |
| A. | 60 degree |
| B. | 90 degree |
| C. | 120 degree |
| D. | 150 degree |
| Answer» D. 150 degree | |
| 44. |
In a lossless inverter, the average power absorbed in one period by the load must be |
| A. | Equal to the average power supplied by the dc source |
| B. | Greater than the average power supplied by the dc source |
| C. | Lesser than the average power supplied by the dc source |
| D. | Equal to the average power supplied by the ac source |
| Answer» B. Greater than the average power supplied by the dc source | |
| 45. |
In a full bridge VSI, in order to avoid the short circuit across the DC bus and the undefined AC output voltage condition, the modulating technique should ensure that |
| A. | Top switch of each leg is on at any instant |
| B. | Bottom switch of each leg is on at any instant |
| C. | Either (a) or (b) |
| D. | None of these |
| Answer» D. None of these | |
| 46. |
In a flyback converter, the inductor of the buck-boost converter has been replaced by a |
| A. | Flyback capacitor |
| B. | Flyback resistor |
| C. | Flyback transformer |
| D. | Flyback transistor |
| Answer» D. Flyback transistor | |
| 47. |
In a 3 phase VSI SPWM to use a single carrier signal and preserve the features of PWM technique, the normalized carrier frequency should be |
| A. | Multiple of two |
| B. | Odd multiple of three |
| C. | Odd multiple of five |
| D. | Odd multiple of seven |
| Answer» C. Odd multiple of five | |
| 48. |
In a 3 phase VSI out of eight valid states, the number of valid states that produce zero ac line voltages is/are |
| A. | One |
| B. | two |
| C. | Three |
| D. | Four |
| Answer» C. Three | |
| 49. |
In a 3 phase half wave rectifier, when firing angle is less than 90 degree, then the average dc output voltage becomes |
| A. | Positive |
| B. | Negative |
| C. | Zero |
| D. | None of these |
| Answer» B. Negative | |
| 50. |
In a 3 phase CSI, if the required line output voltages are balanced and 120 degree out of phase, then the chopping angles are used to eliminate only the harmonics at frequencies |
| A. | 5 |
| B. | 7 |
| C. | 11 |
| D. | All of these |
| Answer» E. | |