1.
Commutation overlap in the phase-controlled ac to dc converter is due to
2.
What is basically a two-terminal parallel-inverse combination of semiconductor layers that permits triggering in either direction?
3.
Which one of the following is the most suitable device for a dc to dc converter?
4.
How many semiconductor layers does an SCR have?
5.
Turned-on of a thyristor takes place when
6.
As compared to power MOSFET, a BJT has
7.
To turn off the SCR, which of the following is done?
8.
An emitter follower regulator has the following disadvantage :
9.
The torque produced by a single-phase induction motor fed through an ac voltage controller for speed control is due to
10.
The sharing of the voltage between thyristors operating in series is influenced by their
11.
The minimum gate current which can turn on SCR is called:
12.
Which of the following is the normal way to turn on a diac?
13.
The use of multiphase rectifier in place of one phase rectifier results in
15.
When the temperature increases, the inter-base resistance of a UJT
16.
Turn-on and turn-off times of transistor depend on
17.
Which of the following devices should be used as a switch in a low power switched mode power supply (SMPS) ?
18.
A thyristor has its gate current zero. To start conduction the forward voltage must exceed
19.
Snubber circuits are used to protect thyristor from which of the following?
20.
Most SCRs can be turned-off by voltage reversal during negative half cycle of the ac supply for
21.
Which one of the following is NOT the advantage of solid state switching of ac capacitors into ac supply over relay-based switching?
22.
Which of the following does not cause permanent damage to an SCR?
23.
An ideal regulated power supply should have
24.
For a BJT α = 0.98, then β =
25.
Latching current of an SCR is
26.
Which of the following is a four-layer diode with an anode gate and a cathode gate?
27.
In order to get best results per unit cost, the heat sinks, on which the thyristors are mounted , are made of
28.
The device commonly used for triggering a triac is
29.
The triac can be used only in
30.
In a self-controlled synchronous motor fed from a variable frequency inverter
31.
The SCR can exercise control over of ac supply.
32.
When cathode of a thyristor is made more positive than its anode
33.
An advantage of cycloconverter is
34.
Conductivity modulation is phenomenon which occurs in
35.
What region lies between the peak point and valley point of UJT emitter characteristic?
37.
A diac has how many terminals?
38.
In a thyristor dc chopper, which type of commutation results in best performance ?
39.
In a UPS, the solid state switch normally transfer supply within
40.
An RC snubber circuit is used to protect a thyristor against:
42.
Thyristor as a solid state relay is useful
43.
Which of the following is NOT a method primarily used for density sensing?
44.
Which terminal does not belong to the SCR?
45.
A modern power semiconductor device that combines the characteristics of BJT and MOSFET is
46.
A power supply has full-load voltage of 24V. What is its no-load voltage for 5% regulation (rounded to the nearest integer) ?
47.
A thyristor can be termed as
49.
What is the control element in an SCR?
50.
A freewheeling diode in a phase-controlled rectifier
