1.
The basic difference between a series regulator and a shunt regulator is
2.
In a UPS, the solid state switch normally transfer supply within
3.
Turn-off time of a thyristor
4.
A feedback control system in which the controlled variable is mechanical position.
5.
The minimum gate current which can turn on SCR is called:
6.
The value of anode current required to maintain the conduction of an SCR even though the gate signal is removed is called as the
7.
Which equation defines the intrinsic stand off ratio (y) of UJTs?
8.
What is a solid state equivalent of a gas filled triode?
9.
For an SCR, dv/dt protection is achieved through the use of
10.
Which one of the following statements regarding the two-transistor model of the p-n-p-n four-layer device is correct?
11.
What are some areas where GTO is applicable?
13.
The advantage of using a freewheeling diode with bridge type ac/dc converterr is
15.
Which is four terminal device
16.
The quality of output ac voltage of a cycloconverter is improved with
17.
Once an SCR is turned on, it remains so until the anode current goes below
18.
Which is equivalent to a zener or avalanche region of the fundamental two-layer semiconductor diode?
19.
Turned-on of a thyristor takes place when
21.
Power electronics deals with the control of ac power at what frequencies essentially?
22.
What is that voltage above when the SCR enters the conduction region?
23.
A single-phase full converter gives maximum and minimum output voltage at firing angles of
24.
In order to get best results per unit cost, the heat sinks, on which the thyristors are mounted , are made of
25.
A normally operated SCR has an anode which is _____ with respect to cathode.
27.
When fed from a fully controlled rectifier, a dc motor, driving an active load can operate in
28.
What is an automatic speed control device using the centrifugal force on rotating flyweights as the feedback element?
29.
Switching regulators are also called
30.
Static voltage equalization in series connected SCRs is obtained by the use of
31.
The shunt type regulator is suitable for which of the following?
32.
The snubber circuit is used in thyristor circuits for
33.
A motor armature supplied through phase controlled SCRs receives a smoother voltage shape at
34.
A boost-regulator has an input voltage of 5V and the average output voltage of 15 V. The duty cycle is
35.
Which is the control element in an SCR?
36.
What is that value of current below which the SCR switches from the conduction state to the forward blocking region under stated conditions?
37.
SCR turns OFF from conducting state to blocking on
38.
When the temperature increases, the inter-base resistance of a UJT
39.
Natural commutation can be used in:
40.
When the firing angle of SCR is increased, its output
41.
What is the typical turn-on time of an SCR?
42.
Turned-off time of a thyristor
43.
A transduction principle used primarily in optical sensors.
44.
Which one of the following is the most suitable device for a dc to dc converter?
45.
When cathode of a thyristor is made more positive than its anode
46.
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
47.
The most suitable device for high frequency inversions in SMPS is
48.
When the emitter terminal of a UJT is open, the resistance between the base-terminals is generally
49.
An SCR triggered by a current pulse through its gate can be turned off by
50.
Thyristor is nothing but a
