1.
The dv/dt effect in SCR can result in
2.
In ac motor control, the ratio of voltage-to-frequency is maintained at constant value
3.
In a 3 phase fully controlled converter the firing frequency is
4.
An ideal regulated power supply should have
5.
SCR turns OFF from conducting state to blocking on
6.
Which of the following devices does not belong to the transistor family?
7.
Which of the following configurations is used for both motoring and regenerative braking?
8.
The use of multiphase rectifier in place of one phase rectifier results in
10.
How many pn junction does SCRs have?
11.
The minimum gate current which can turn on SCR is called:
12.
ECG stands for electrocardiography while EEG stands for?
13.
An SCR is made of what material?
15.
Which of the following does not cause permanent damage to an SCR?
16.
1. An SCR whose state is controlled by the light falling upon a silicon semiconductor layer of the device.
17.
The triac is equivalent to
18.
With gate open, if the supply voltage exceeds the breakover voltage of SCR, then SCR will conduct
19.
In a single-phase semiconverter with resistive load and for a firing angle α , each SCR conduction and freewheeling action takes place
20.
Which one of the following is the most suitable device for a dc to dc converter?
21.
The three terminals of an SCR are the
22.
Which one of the following statements is correct? In the case of load regulation
23.
Why is an external pass resistor used in a voltage regulator ?
24.
In order to get best results per unit cost, the heat sinks, on which the thyristors are mounted , are made of
25.
A thyristor can be termed as
26.
In a feedback series regulator circuit, the output voltage is regulated by controlling the
27.
After firing an SCR, the gate pulse is removed . The current in the SCR will
28.
Consider the following semiconductor devices:
1. Triac 2. Thyristor 3. amplifying gate thyristor
The correct sequence of these devices in increasing order of their di/dt capabilities is
29.
Which is suitable for making the variable frequency drives
30.
Most SCRs can be turned-off by voltage reversal during negative half cycle of the ac supply for
31.
Which semiconductor device acts like a diode and two transistor?
32.
Thyristor as a solid state relay is useful
33.
What is that voltage above when the SCR enters the conduction region?
34.
Thyristor is nothing but a
35.
Which of the following can change the angle of conduction in SCR?
36.
The quality of output ac voltage of a cycloconverter is improved with
37.
Which is the control element in an SCR?
38.
Which of the following is a common application of UJT?
39.
The output voltage in a switching regulator for an input Vin and duty cycle δ is
40.
An SCR is considered to be a semicontrolled device because
41.
In a single-phase full wave regulator, the firing angles in the positive and negative half cycles are generally.
42.
Freewheeling diode at the output of a rectifier allows
43.
The typical turn-off time of an SCR is about
45.
When the emitter terminal of a UJT is open, the resistance between the base-terminals is generally
46.
Turn-off time of a thyristor
47.
Which one of the following is NOT the advantage of solid state switching of ac capacitors into ac supply over relay-based switching?
48.
Power electronics deals with the control of ac power at what frequencies essentially?
49.
A transduction principle used primarily in optical sensors.
