Worksheetssingle phase Controlled converters
Total questions: 25
Worksheet time: 13mins
A triac can pass a portion of …………… half-cycle through the load
Only positive
Only negative
Both positive and negative
None of the above
Q3. A triac is a …………. switch
None of the above
Bidirectional
Unidirectional
Mechanical
None of the above
Q1. A Triac has three terminals viz ………………
Drain, source, gate
Two main terminal and a gate terminal
Cathode, anode, gate
Cathode, anode, emitter
An IGBT is a -------
current controlled device
voltage controlled device
both current and voltage
resistance controlled device
In the below shown circuit, considering the load to be purely R load, the thyristor T2 would conduct from ωt =
0 to π
α to π
π+α to 2π
π to 2π+α
3. For a single pulse M-2 rectifier with RL load and firing angle α >0°, the value of the inductance L is such that the load current is continuous.
Choose the correct statement.
The load current can never be positive
The load current can never be negative
The load current can never be zero
The load current is a constant DC
For the circuit M-2, the transformer ratio is 1:1 and Vs = Vm sinωt. When T1 is forward biased and is triggered at α than T2 is
subjected to a forward voltage of Vm sinα
subjected to a forward voltage of 2Vm sinα
subjected to a reverse voltage of Vm sinα
subjected to a reverse voltage of 2Vm sinα
A semi-converter circuit gives the following voltage waveform. Find the expression for the average output voltage with Vs = Vm sinωt and firing angle α
(Vm/π) cosα
(Vm/π) (1+cosα)
(2Vm/π) cosα
(2Vm/π) (1+cosα)
A single phase full-converter using R load is a _________ quadrant converter and that using an RL load without FD is a __________ quadrant converter
one, one
two, one
one, two
two, two
In case of controlled rectifiers, the nature of the load current (continues or discontinuous) depends upon the
type of load and firing angle
only on the type of load
only on the firing angle
it is independent of all the parameters
With respect to the below given circuit, from ωt = 0 to α, ____ thyristor(s) block the forward voltage
T1 and T2
T2
T3 and T4
T4
For the given circuit, when the devices T1 and T2 are conducting from ωt = α till they are naturally commutated at π voltage across the other two pair of devices is
zero
positive( forward voltage)
negative (reverse voltage)
None of the above
For the above shown circuit with continuous load current.
Each thyristor pair conducts for
π radians
2π radians
< π radians
> π radians
For the above shown circuit has dis-continuous load current waveform.
π radians
2π radians
< π radians
> π radians
The above shown rectifier configuration has continues load current, find the expression for the average value of output voltage when the supply Vs = Vm sinωt is connected.
(Vm/π) cosα
(2Vm/π) cosα
(Vm/π) (1+cosα)
(2Vm/π) (1+cosα)
In converter operation, with output voltage = Vo and RLE load.
Vo < E
Vo = E
Vo > E
None of the mentioned
A single-phase Asymmetrical semi-converter employs
one SCR and one diode in each leg
two SCRs and two diodes in each leg
two SCRs in each leg
two diodes in each leg
In converter (rectifier)operation, with output voltage = Vo and RLE load.
Vo < E
Vo = E
Vo > E
None of the mentioned
A single-phase full converter bridge type connection has a RLE type of motor load connected. The minimum requirement to turn-on the device is
α > 30°
Vm sinα > E
Vm sinα < E
α < 30°
In which chopper average voltage output (Vo) in a step up chopper is greater than the voltage input (Vs)?
Step Down Chopper
Step Up chopper
Step Up/Down Chopper
All of the given
The average value of the output voltage in a step - down dc chopper is given bya. b. c. d. V 0 = V s / ( 1 - D )
V 0 = V s
V 0 = D V s
V 0 = V s / D
V 0 = V s / ( 1 - D )
Choppers is a
AC - DC converters
AC - AC converter
DC - AC converters
DC - DC converters
The voltage in a single phase half wave inverter varies between
Vs and 0
Vs/2 and 0
Vs/2 and –Vs/2
Vs and –Vs
The output current wave of a single-phase full bridge inverter on RL load is
a sine wave
a square wave
a triangular wave
constant dc
Single-phase full bridge inverters requires
4 SCRs and 2 diodes
4 SCRs and 4 diodes
2 SCRs and 4 diodes
2 SCRs and 2 diodes
