421.
In a three phase converter, the number of notches per cycle is
A
Three
B
Six
C
One
D
Nine
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In a three phase converter, the number of notches per cycle is
Three
Six
One
Nine
In a load commutated DC - DC chopper, the capacitor has a
Symmetric rectangular voltage across itself
Symmetric trapezoidal voltage across itself
Symmetric triangular voltage across itself
Symmetric sinusoidal voltage across itself
In a 3 phaseCSI, if the required line output voltages are balanced and 120 degreeout of phase, then the chopping angles are used to eliminate only theharmonics at frequencies
7
11
5
All of these
Harmonics in 3 phase inverters can be reduced by using
Active filter
Both passive and active filters
Passive filter
None of these
For sweptfrequency measurements, the input impedance of the mismatched transmission line would vary with frequency as the electrical length ofthe transmission line would
Remains same with change in frequency
Increase with frequency
Decrease with frequency
Either (a or b)
For similar carrier and modulating signals, the line current used in CSI is
Identical to line current in VSI
Identical to phase voltage in VSI
Identical to line voltage in a VSI
Identical to phase voltage in CSI
For bidirectional operation of converters
A parallel combination of controllable switch and capacitor is used
A series combination of controllable switch and a diode is used
A parallel combination of controllable switch and a diode is used
A series combination of controllable switch and a capacitor is used
For a buck converter to reduce the conduction losses in diode
A low on - resistance switch can be added in parallel
A high on - resistance switch can be added in series
A high on - resistance switch can be added in parallel
A low on - resistance switch can be added in series
During the commutation period in 3 phase converter, overlap time is
Dependent on the voltage
Dependent on both the load current and load voltage behind the short circuit current
Dependent on the load current
Independent on both the load current and load voltage
Double fourier series analysis of PWM is
Three dimensional functions
One dimensional functions
Two dimensional functions
All of these
Between the peak point and the valley point of UJT emitter characteristics we have ....................... region
Negative resistance
Cut-off
Saturation
None of the above
Between the incoming and outgoing devices in voltage commutation
Small overlapping operation
No overlapping operation
Large overlapping takes place
None of these
An SCR is made up of silicon because
silicon has small leakage current than germanium
silicon has small leakage voltage than germanium
silicon has large leakage current than germanium
silicon has large leakage voltage than germanium
An SCR can be used
for power control
for speed control of dc shunt motor
as static conductor
all of these
After peak point, the UJT operates in the ................... region
Saturation
Negative resistance
Cut-off
None of the above
AC power in a load can be controlled by using
two SCRs in parallel opposition
four SCRs in series
two SCRs in series
three SCRs in series
A UJT is sometimes called................ diode
Low resistance
Double-base
High resistance
Single-base
A UJT has ....................
Two pn junctions
None of the above
One pn junction
Three pn junctions
A triac is equivalent to two SCRs .......................
In parallel
None of the above
In series
In inverse-parallel
A triac is a ................ switch
Bidirectional
None of the above
Unidirectional
Mechanical