1.
In the forward blocking region of a silicon controlled rectifier, the SCR is
2.
Which of the following is the normal way to turn on a diac?
3.
The advantage of using a freewheeling diode with bridge type ac/dc converterr is
4.
The V-I characteristics for a triac in the first and third quadrants are essentially identical to those of in the quotation.
5.
Which semiconductor device acts like a diode and two transistor?
6.
Which of the following is a four-layer diode with an anode gate and a cathode gate?
7.
The triac can be used only in
9.
1. An SCR whose state is controlled by the light falling upon a silicon semiconductor layer of the device.
10.
What is the typical turn-on time of an SCR?
11.
The voltage across an SCR when it is turned on is about
12.
What region lies between the peak point and valley point of UJT emitter characteristic?
13.
When the SCR is OFF, the current in the circuit is
14.
When the supply voltage exceeds the breakover voltage of an SCR, it
15.
The input power factor of the converter is
16.
Commutation overlap in the phase-controlled ac to dc converter is due to
17.
Which of the following is NOT a method primarily used for density sensing?
18.
Snubber circuits are used to protect thyristor from which of the following?
19.
The output voltage in a switching regulator for an input Vin and duty cycle δ is
20.
To turn on the UJT, the forward bias on emitter diode should be______ the peak point voltage.
21.
Most SCRs can be turned-off by voltage reversal during negative half cycle of the ac supply for
22.
When cathode of a thyristor is made more positive than its anode
23.
An SCR remains turned on if the anode current is more than
24.
Turn-off time of a thyristor
25.
Turned-off time of a thyristor
26.
An SCR is in conducting state, a reverse voltage is applied between anode and cathode, but it fails to turn off. what could be the reason?
27.
A thyristor has its gate current zero. To start conduction the forward voltage must exceed
28.
Why is an external pass resistor used in a voltage regulator ?
29.
Static voltage equalization in series connected SCRs is obtained by the use of
30.
In a singe-phase full-wave controlled bridge rectifier, minimum output voltage and maximum output voltage are obtained at which conduction angles?
31.
Control system that maintains a speed voltage, or other variable within specified limits of a preset level.
32.
For an SCR, dv/dt protection is achieved through the use of
33.
Which of the following configurations is used for both motoring and regenerative braking?
34.
Two thyristor of same rating and same specifications
35.
R-C snubber is used in parallel with the thyristor to
36.
Which is equivalent to a zener or avalanche region of the fundamental two-layer semiconductor diode?
37.
di/dt protection is provided to the thyristor by
38.
What is the required gate triggering current of GTO?
39.
Once an SCR is turned on, it remains so until the anode current goes below
40.
Freewheeling diode at the output of a rectifier allows
42.
Natural commutation can be used in:
43.
When the temperature increases, the inter-base resistance of a UJT
44.
An SCR is a member of what family?
45.
A UJT is sometimes called a______diode.
46.
Latching current of an SCR is
47.
What is the control element in an SCR?
48.
The terminals of a power MOSFET are called
49.
SCR turns OFF from conducting state to blocking on
50.
The quality of output ac voltage of a cycloconverter is improved with
