Explore topic-wise MCQs in Electrical Engineering Questions.

This section includes 217 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.

151.

Dynamic equalising circuit is useful____________?
A. To limit di / dt of SCR
B. To limit dV / dt of SCR
C. For voltage equalisation
D. Both B and C
Answer» E.
Discussion
152.

A GTO can be turned on by applying___________?
A. Positive gate signal
B. Positive drain signal
C. Positive source signal
D. None of these
Answer» B. Positive drain signal
Discussion
153.

During reverse recovery time__________________?
A. charge carrier of junction J2 recombined
B. charge carrier of junction J1 is swept out
C. charge carrier of junction J3 is swept out
D. both B and C
Answer» E.
Discussion
154.

Snubber circuit is used with SCR_________________?
A. in series
B. in parallel
C. either series or parallel
D. anti parallel
Answer» C. either series or parallel
Discussion
155.

A single phase ac – dc converter is also known as____________?
A. rectifier
B. inverter
C. chopper
D. regulator
Answer» B. inverter
Discussion
156.

Which of following is not a power transistor?
A. IGBTs
B. COOLMOS
C. TRIAC
D. SITS
Answer» D. SITS
Discussion
157.

During which time maximum conduction spreading take place in the thyristor during turn ON?
A. Delay time
B. Spread time
C. Rise time
D. Same for every case
Answer» C. Rise time
Discussion
158.

SCRs are used in series to meet_______________?
A. high current demand
B. low voltage demand
C. low current demand
D. high voltage demand
Answer» E.
Discussion
159.

SITH is also known as___________?
A. Filled controlled diode
B. Filled controlled rectifier
C. Silicon controlled rectifier
D. None of these
Answer» B. Filled controlled rectifier
Discussion
160.

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
Discussion
161.

ON state voltage drop across SCR lie between the range_____________?
A. 0 – 0.5 V.
B. 0.5 – 1 V.
C. 1 – 1.5 V.
D. 1.5 – 2 V.
Answer» D. 1.5 – 2 V.
Discussion
162.

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
Discussion
163.

Which following is a two terminal three layer device?
A. BJT
B. Power dioed
C. MOSFET
D. None of above
Answer» E.
Discussion
164.

In a single phase full wave rectifier, during blocking state the pea inverse voltage of diode is______________?
A. V m
B. 2 V m
C. V m / 2
D. 4 V m
Answer» C. V m / 2
Discussion
165.

Dynamic equalizing circuit is used for________________?
A. equal division of voltage across each thyristor
B. equal division of current through each thyristor in parallel
C. equal division of voltage across each thyristor in parallel
D. equal division of current through each thyristor in series
Answer» B. equal division of current through each thyristor in parallel
Discussion
166.

Unipolar modulation is generally used in____________?
A. AC – AC converters
B. AC – DC converters
C. DC – AC converters
D. DC – DC converters
Answer» E.
Discussion
167.

60 thyrsistors are connected in series and parallel to form a 10 KV and 5.5 KA switch. Each thyristor is rated for 1.2 KV, 1 KA. The no. of parallel path are 6. The efficiency of the switch is______________________?
A. 76.3 %
B. 91.6 %
C. 83.3 %
D. 90.9 %
Answer» B. 91.6 %
Discussion
168.

A string of n parallel SCRs is operated at 72 KA, the rating of each SCR is 1 KA. If derating factor of the string is 0.1. value of n will be___________?
A. 60
B. 70
C. 80
D. 90
Answer» D. 90
Discussion
169.

A thyristor string is made of a no. of SCR connected in series and parallel. The string have volume and current of 11 KV and 4 KA. The voltage and current rating of available SCRs are 1800 V and 1000 A. For a string efficiency of 90 % let the number of SCRs in series and parallel are a and b respectively. Then the value of a and b will be_____________?
A. 5, 7
B. 4, 6
C. 7, 5
D. 6, 4
Answer» D. 6, 4
Discussion
170.

An ideal switch is___________?
A. Lossless
B. Carry current in any direction when it is on
C. Does not carry any current in any direction when it is off
D. All of these
Answer» E.
Discussion
171.

For power output higher than 15 kW, the suitable rectifier is________________?
A. Single phase
B. 3 phase
C. Poly phase
D. Only (b) and (c)
Answer» E.
Discussion
172.

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
Discussion
173.

Electrical power output in a d.c. generator is equal to____________?
A. Electrical power developed in armature – copper losses
B. Mechanical power input – iron and friction losses
C. Electrical power developed in armature – iron and copper losses
D. Mechanical power input – iron and friction losses – copper losses
Answer» E.
Discussion
174.

IGBT stands for___________?
A. Insulated gate bipolar transistor
B. Insulated gate bidirectional transistor
C. Inductive gate bipolar transistor
D. Inductive gate bidirectional transistor
Answer» B. Insulated gate bidirectional transistor
Discussion
175.

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
Discussion
176.

DIAC are specifically designed to trigger______________?
A. TRIAC
B. SCR
C. GTO
D. Only (a) and (b)
Answer» E.
Discussion
177.

If the gate voltage of an SCR is removed, then the_______________?
A. anode current decreases
B. anode current does not decrease at all
C. anode current increases
D. cathode current increases
Answer» C. anode current increases
Discussion
178.

During the commutation period in 3 phase converter, overlap time is_____________?
A. Dependent on the load current
B. Dependent on the voltage
C. Dependent on both the load current and load voltage behind the short circuit current
D. Independent on both the load current and load voltage
Answer» D. Independent on both the load current and load voltage
Discussion
179.

What is used to protect the SCR from over current ________________?
A. CB and fuse
B. Heat sink
C. Snubber circuit
D. Voltage clamping device
Answer» B. Heat sink
Discussion
180.

Single phase VSI are mainly used in___________?
A. Power supplies
B. Ups
C. Multilevel configuration
D. All of these
Answer» E.
Discussion
181.

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
Discussion
182.

In a 3 phase bridge rectifier the ripple frequency is _____________?
A. Equal to the input frequency
B. Twice the input frequency
C. Three times the input frequency
D. Six times the input frequency
Answer» E.
Discussion
183.

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.
Discussion
184.

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.
Discussion
185.

Double edge modulation eliminates certain harmonics when the reference is a__________?
A. Sine wave
B. Square wave
C. Triangular wave
D. Trapezoidal wave
Answer» B. Square wave
Discussion
186.

For similar carrier and modulating signals, the line current used in CSI is__________?
A. Identical to line voltage in a VSI
B. Identical to line current in VSI
C. Identical to phase voltage in VSI
D. Identical to phase voltage in CSI
Answer» B. Identical to line current in VSI
Discussion
187.

A capacitive load in voltage source inverters generates ________________?
A. Small current spikes and can be reduced by using an inductive filter
B. Large current spikes and can be increased by using an inductive filter
C. Small current spikes and can be increased by using an inductive filter
D. Large current spikes and can be reduced by using an inductive filter
Answer» E.
Discussion
188.

In a three phase converter, the number of notches per cycle is____________?
A. One
B. Three
C. Six
D. Nine
Answer» D. Nine
Discussion
189.

The control method used for PWM dc – dc converter is______________?
A. Voltage mode control
B. Current mode control
C. Hysteric control
D. All of these
Answer» E.
Discussion
190.

Any electrical signal present in a circuit other than the desired signal is known as______________?
A. Noise
B. Distortion
C. Interference
D. All of these
Answer» B. Distortion
Discussion
191.

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
Discussion
192.

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
Discussion
193.

The man made noise sources is / are_____________?
A. Motors
B. Switches, radio interferences
C. Computers, digital electronics
D. All of these
Answer» E.
Discussion
194.

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
Discussion
195.

In single phase VSI, the harmonic which is not present is____________?
A. 2nd
B. 3rd
C. 5th
D. 7th
Answer» B. 3rd
Discussion
196.

Very large values of modulation index (greater than 3.24) lead to___________?
A. Square AC output voltage
B. Sine AC output voltage
C. Triangular AC output voltage
D. Trapezoidal AC output voltage
Answer» B. Sine AC output voltage
Discussion
197.

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.
Discussion
198.

Double fourier series analysis of PWM is_____________?
A. Two dimensional functions
B. Three dimensional functions
C. One dimensional functions
D. All of these
Answer» B. Three dimensional functions
Discussion
199.

A Triac has three terminals viz ___________?
A. Drain, source, gate
B. Two main terminal and a gate terminal
C. Cathode, anode, gate
D. None of the above
Answer» C. Cathode, anode, gate
Discussion
200.

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
Discussion