GATE Electrical Engineering

The 3-phase modulating waveforms $\left(v_a(t), v_b(t), v_c(t)\right)$, used in sinusoidal PWM in a voltage source inverter (VSI) are $$ \begin{aligned} & v_a(t)=0.8 \sin (\omega t...

If the following switching devices have similar power ratings, which one of them is the fastest?

A single-phase triac based AC voltage controller feeds a series RL load. The input AC supply is 230 V, 50 Hz. The values of R and L are 10 Ω and 18.37 mH, respectively. The minimum...

A single-phase half-controlled bridge converter supplies an inductive load with ripple free load current. The triggering angle of the converter is 60°. The ratio of the rms value o...

A single-phase full bridge voltage source inverter (VSI) feeds a purely inductive load. The inverter output voltage is a square wave in 180° conduction mode. The fundamental freque...

A single-phase full-controlled thyristor converter bridge is used for regenerative braking of a separately excited DC motor with the following specifications: Rated armature voltag...

A charger supplies 100 W at 20 V for charging the battery of a laptop. The power devices, used in the converter inside the charger, operate at a switching frequency of 200 kHz. Whi...

A single-phase full-bridge diode rectifier feeds a resistive load of 50 $$\Omega$$ from a 200 V, 50 Hz single phase AC supply. If the diodes are ideal, then the active power, in wa...

The voltage at the input of an AC-DC rectifier is given by $$v(t) = 230\sqrt 2 \sin \omega t$$ where $$\omega = 2\pi \times 50$$ rad/s. The input current drawn by the rectifier is...

A 3-phase grid-connected voltage source converter with DC link voltage of 1000 V is switched using sinusoidal Pulse Width Modulation (PWM) technique. If the rid phase current is 10...

A phase-controlled, single-phase, full-bridge converter is fed from a $$230$$ $$V,$$ $$50$$ $$Hz,$$ $$AC$$ source. The fundamental frequency in $$Hz$$ of the voltage ripple on the...

For the power semiconductor devices $$IGBT, MOSFET,$$ Diode and Thyristor, which one of the following statements is TRUE?

A three-phase voltage source inverter with ideal devices operating in $${180^ \circ }$$ conduction mode is feeding a balanced star-connected resistive load. The $$DC$$ voltage inpu...

A full-bridge converter supplying an RLE load is shown in figure. The firing angle of the bridge converter is 120º. The supply voltage $$${v_m}\left( t \right) = 200\pi \sin \left(...

A step-up chopper is used to feed a load at $$400$$ $$V$$ $$dc$$ from a $$250$$ $$V$$ $$dc$$ source. The inductor current is continuous. If the ‘off’ time of the switch is $$20\,\,...

A single-phase $$SCR$$ based $$ac$$ regulator is feeding power to a load consisting of $$5\,\,\Omega $$ resistance and $$16$$ $$mH$$ inductance. The input supply is $$230$$ $$V,$$...

The typical ratio of latching current to holding current in a $$20$$ $$A$$ thyristor is

A half-controlled single-phase bridge rectifier is supplying an $$R$$-$$L$$ load. It is operated at a firing angle $$α$$ and the load current is continuous. The fraction of cycle t...

The input voltage given to a converter is $${V_i} = 100\sqrt 2 \,\,\,\sin \,\,\,\left( {100\pi t} \right)\,\,V$$ The current drawn by the converter is $${i_i} = 10\sqrt 2 \,\,\,\si...

Circuit turn-off time of an $$SCR$$ is defined as the time

The input voltage given to a converter is $${V_i} = 100\sqrt 2 \,\,\,\sin \,\,\,\left( {100\pi t} \right)\,\,V$$ The current drawn by the converter is $${i_i} = 10\sqrt 2 \,\,\,\si...

An $$SCR$$ is considered to be a semi - controlled device because

A single phase full bridge converter supplies a load drawing constant and ripple free load current. If the triggering angle is $${30^ \circ },$$ the input power factor will be

A three phase fully controlled bridge converter is feeding a load drawing a constant and ripple free load current of $$10$$ $$A$$ at a firing angle of $${30^ \circ }.$$ The approxi...

A $$3$$ - phase voltage source Inverter is operated in $${180^ \circ }$$ conduction mode. Which one of the following statements is true?

A single $$-$$ phase fully controlled thyristor bridge $$ac$$ $$-$$ $$dc$$ converter is operating at a firing angle of $${25^ \circ }$$ and an overlap angle of $${10^ \circ }$$ con...

A $$1:1$$ pulse transformer $$(PT)$$ is used to trigger the $$SCR$$ in the adjacent figure. The $$SCR$$ is rated at $$1.5$$ $$kV$$, $$250$$ $$A$$ with $${{\rm I}_L} = 250\,mA,\,\,{...

A single - phase voltage source inverter is controlled in a single pulse - width modulated mode with a pulse width of $${150^0}$$ in each half cycle. Total harmonic distortion is d...

A three - phase fully - controlled thyristor bridge converter is used as line commuted inverter to feed $$50kW$$ power $$420$$ $$V$$ $$dc$$ to a three phase, $$415$$ $$V$$ (line),...

A single phase full $$-$$ wave half $$-$$ controlled bridge converter feeds an inductive load. The two $$SCR's$$ in the converter are connected to a common $$DC$$ bus. The converte...

''Six $$MOSFETS$$ connected in a bridge configuration (having no other power device) MUST be operated as Voltage Source Inverter $$(VSI)''.$$ This statement is

A single $$-$$ phase, $$230$$ $$V$$, $$50$$ $$Hz$$ $$ac$$ mains fed step down transformer $$(4:1)$$ is supplying power to a half $$-$$ wave uncontrolled $$ac$$ $$-$$ $$dc$$ convert...

A $$3$$ $$-$$ phase fully controlled bridge converter with free wheeling diode is fed from $$400$$ $$V$$, $$50$$ $$Hz$$ $$AC$$ source and is operating at a firing angle of $${60^ \...

A solar cell of $$350V$$ is feeding power to an $$ac$$ supply of $$440$$ $$V,$$ $$50$$ $$Hz$$ through a $$3$$- phase fully controlled briodge converter. A large inductance is conne...

The conduction loss versus device current characteristic of a power $$MOSFET$$ is best approximated by

The output voltage waveform of a three - phase square-wave inverter contains

A three - phase diode bridge rectifier is fed from a $$400$$ $$V$$ $$RMS$$. $$50$$ $$Hz$$, three $$-$$ phase $$AC$$ source. If the load is purely resistive, then peak instantaneous...

A bipolar junction transistor $$(BJT)$$ is used as a power control switch by biasing it in the cut-off region (OFF state) or in the saturation region (ON state). In the ON state, f...

A step down chopper is operated in the continuous conduction mode in steady state with a constant duty ratio $$D.$$ If $${V_0}$$ is the magnitude of the $$dc$$ output voltage and i...

A three phase thyristor bridge rectifier is used in a $$HVDC$$ link. The firing angle $$\alpha $$ (as measured from the point of natural commutation) is constrained to lie between...

A six pulse thyristor rectifier bridge is connected to a balanced $$50Hz$$ three phase $$ac$$ source. Assuming that the $$dc$$ output current of the rectifier is constant, the lowe...

A $$dc$$ motor with armature resistance $${R_a}$$ is fed from a step down chopper in the continuous mode, and operates at some known speed and known excitation current. The motor c...

A thyristorised three phase fully controlled converter feeds a $$dc$$ load that draws a constant current. Then the input $$ac$$ line current to the converter has

Triangular $$PWM$$ control, when applied to a $$BJT$$ based three phase voltage source inverter, introduces.

A three phase voltage source inverter supplies a purely inductive three phase load. Upon Fourier analysis, the output voltage waveform is found to have an $${h^{th}}$$ order harmon...

A single phase voltage source of magnitude $${V_s}$$ and frequency $$\omega \,\,\left( {rad\,/\,\sec } \right)$$ is connected to an inductance $$L$$ through an antiparallel back-to...

A step down chopper operates from a $$dc$$ voltage source $${V_s}$$ feeds a $$dc$$ motor armature with a back $$e.m.f$$ $$\,\,{E_b}.$$ From oscilloscope traces, it is found that th...

A $$PWM$$ switching scheme is used with a three phase inverter to

Resonant Converter's are basically used to

A three phase diode bridge is used to provide rectified output from a $$400V,$$ $$50$$ $$Hz,$$ $$3$$- phase supply to a $$R$$ $$-$$ $$L$$ load with $$10\,\,\Omega $$ resistance and...

A $$3$$-phsae, fully controlled, converter is feeding power into a $$d.c.$$ load at a constant current of $$150A.$$ The $$r.m.s$$ current through each thyristor of the converter is

The $$MOSFET$$ switch in its on - state may be considered equivalent to

In a commutation circuit employed to turn off an $$SCR$$, Satisfactory turn-off is obtained when.

When the firing angle $$\alpha $$ of a single phase, fully controlled rectifier feeding constant $$d.c.$$ current into a load is $${30^ \circ }$$ , the displacement power factor of...

The uncontrolled electronic switch employed in power electronic converters is

If a diode is connected in anti - parallel with a thyristor, then

An $$SCR$$ is connected in series with a $$300V$$ $$ac$$ supply and a $$300$$ ohms load resistor calculate (a) The reading of a moving coil ammeter connected in series with the loa...

A single - phase bridge inverter is fed from a $$200V$$ $$d.c$$ supply and is operated at $$50$$ $$Hz.$$ It is connected to a load having a resistance of $$20$$ $$ohms$$ and an ind...

In a dual converter, the circulating current

Which semiconductor power device out of the following is not a current triggered device?

In a thyristor $$dc$$ chopper which type of commutation results in best performance?

The Triac can be used only in

Which of the following does not cause permanent damage of an $$SCR?$$

A $$dc$$ to $$dc$$ transistor chopper supplied from a fixed voltage $$dc$$ source feeds a fixed resistive-inductive load and a free-wheeling diode. The chopper operates at $$1$$ $$...

An inverter capable of supplying a balanced three - phase variable voltage variable frequency output is feeding a three - phase induction motor rated for $$50$$ $$Hz$$ and $$440V.$...

A three phase $$ac$$-to-$$dc$$ diode bridge rectifier is supplied from a three-phase, $$440V$$ source. The rectifier supplies a purely resistive load. The average $$dc$$ voltage ac...

A single phase Inverter with square wave output voltage will have in its output waveform a fifth harmonic component equal to ______ percentage of the fundamental

A line - commutated inverter changes $$dc$$ voltage to $$ac$$ voltage

A switched mode power supply operating at $$20$$ $$kHz$$ to $$100$$ $$kHz$$ range uses as the main switching element

The output voltage of a six - pulse double star rectifier is the same as that of a three - phase half wave rectifier

Thysistor circuits that directly convert poly phase $$ac$$ voltage from one frequency to another frequency are called _______.

Match the following List $$-$$ $${\rm I}$$ $$A.$$ Commutation $$B.$$ $$V$$ $$-$$ Curves $$C.$$ Free wheeling diode $$D.$$ Overlap List $$-$$ $${\rm II}$$ $$P.$$ Resistive load $$Q....

A triac can be triggered by a gate pulse of __________ polarity

A chopper operating at a fixed frequency is feeding an $$R$$-$$L$$ load. As the duty ratio of the chopper is increased from $$25\% $$ to $$75\% $$, the ripple in the load current

The thermal resistance between the body of a power semiconductor device and the ambient is expressed as

When a line commutated converter operates in the inverter mode