1.
A thyristor controlled reactor, the firing angle of thyristor is to be controlled in the range of
2.
Which of the following configurations is used for both motoring and regenerative braking?
3.
The device commonly used for triggering a triac is
4.
In a chopper fed dc drive , the chopping frequency is approximately equal to
5.
An SCR is made of what material?
6.
Thyristor is nothing but a
7.
When the supply voltage exceeds the breakover voltage of an SCR, it
8.
Which semiconductor device acts like a diode and two transistor?
9.
Which device exhibits negative resistance region?
10.
A thyristors are not made using germanium, because
11.
Conductivity modulation is phenomenon which occurs in
12.
What is a three terminal device used to control large current to a load?
13.
The voltage across an SCR when it is turned on is about
15.
Once an SCR is turned on, it remains so until the anode current goes below
16.
What region lies between the peak point and valley point of UJT emitter characteristic?
17.
In a UPS, the solid state switch normally transfer supply within
18.
What is a solid state equivalent of a gas filled triode?
19.
The specified maximum junction temperature of thyristors is about
20.
Thyristor as a solid state relay is useful
21.
In order to get best results per unit cost, the heat sinks, on which the thyristors are mounted , are made of
22.
A resistor connected across the gate and cathode of an SCR
23.
The SCR can exercise control over of ac supply.
24.
A power supply has full-load voltage of 24V. What is its no-load voltage for 5% regulation (rounded to the nearest integer) ?
25.
A motor armature supplied through phase controlled SCRs receives a smoother voltage shape at
26.
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?
27.
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 gateÂ
which of these statement is /are correct
29.
Freewheeling diode at the output of a rectifier allows
30.
AC voltage regulators are widely used in
31.
Which one of the following statements is correct? In the case of load regulation
32.
Which one of the following statements regarding the two-transistor model of the p-n-p-n four-layer device is correct?
34.
The sharing of the voltage between thyristors operating in series is influenced by their
35.
dv/dt protection is provided to the SCR by
36.
The triac can be used only in
37.
Turn-on and turn-off times of transistor depend on
38.
ECG stands for electrocardiography while EEG stands for?
39.
Which of the following can change the angle of conduction in SCR?
40.
Which equation defines the intrinsic stand off ratio (y) of UJTs?
41.
In the forward blocking region of a silicon controlled rectifier, the SCR is
42.
Carrier frequency gate drive is used for turn-on of a thyristor to reduce.
43.
Which of the following is the normal way to turn on an SCR?
44.
A freewheeling diode in a phase-controlled rectifier
45.
In a single-phase full wave regulator, the firing angles in the positive and negative half cycles are generally.
46.
Which is suitable for making the variable frequency drives
47.
The ON voltage and forward breakover of an SCR depend on the
48.
Which transistor conducts current in both directions when turned on?
49.
Snubber circuits are used to protect thyristor from which of the following?
50.
The terminals of a power MOSFET are called
