1.
R-C snubber is used in parallel with the thyristor to
2.
Consider the following statements:
A four-layer PNPN device having two gate leads can be turned on by applying a
1. positive current pulse to the cathode gate
2. positive current pulse to the anode gate
3. negative current pulse to the anode gate
4. negative current pulse to tha cathode gate
which of these statement is /are correct
3.
Which of the following is NOT a method primarily used for density sensing?
4.
What Greek word which means “switch”?
5.
In order to get best results per unit cost, the heat sinks, on which the thyristors are mounted , are made of
6.
When the SCR is OFF, the current in the circuit is
7.
A modern power semiconductor device that combines the characteristics of BJT and MOSFET is
8.
When the supply voltage exceeds the breakover voltage of an SCR, it
9.
An SCR is a _____ triggered device.
10.
Turned-on of a thyristor takes place when
12.
In a single-phase full wave regulator, the firing angles in the positive and negative half cycles are generally.
13.
A transduction principle used primarily in optical sensors.
14.
How many semiconductor layers does an SCR have?
15.
What is that voltage above when the SCR enters the conduction region?
16.
Which semiconductor power device, out of the following, is not a current triggered device?
17.
What is the control element in an SCR?
18.
1. An SCR whose state is controlled by the light falling upon a silicon semiconductor layer of the device.
19.
Which of the following is the normal way to turn on a diac?
20.
Which of the following is a common application of UJT?
21.
The snubber circuit is used in thyristor circuits for
23.
What is a three terminal device used to control large current to a load?
24.
An SCR triggered by a current pulse through its gate can be turned off by
25.
An SCR combines the feature of
26.
A thyristor can be termed as
27.
Which one of the following is the most suitable device for a dc to dc converter?
28.
ECG stands for electrocardiography while EEG stands for?
29.
Natural commutation can be used in:
30.
A motor armature supplied through phase controlled SCRs receives a smoother voltage shape at
31.
In the forward blocking region of a silicon controlled rectifier, the SCR is
32.
Once an SCR is turned on, it remains so until the anode current goes below
33.
Which one of the following is NOT the advantage of solid state switching of ac capacitors into ac supply over relay-based switching?
34.
In a singe-phase full-wave controlled bridge rectifier, minimum output voltage and maximum output voltage are obtained at which conduction angles?
35.
A feedback control system in which the controlled variable is mechanical position.
36.
Which one of the following is used as the main switching element in a switched mode power supply operating in 20 kHz to 100 kHz range?
37.
Static voltage equalization in series connected SCRs is obtained by the use of
38.
Conductivity modulation is phenomenon which occurs in
39.
Which semiconductor device acts like a diode and two transistor?
40.
A single-phase full converter gives maximum and minimum output voltage at firing angles of
41.
A freewheeling diode is connected across R-L load, because
42.
A triac is equivalent to two SCRs
43.
An SCR remains turned on if the anode current is more than
44.
The triac can be used only in
45.
What is that value of current below which the SCR switches from the conduction state to the forward blocking region under stated conditions?
46.
The basic difference between a series regulator and a shunt regulator is
48.
Which of the following devices does not belong to the transistor family?
49.
The quality of output ac voltage of a cycloconverter is improved with
50.
An SCR is considered to be a semicontrolled device because