1.
To turn off the SCR, which of the following is done?
2.
Turned-on of a thyristor takes place when
3.
An RC snubber circuit is used to protect a thyristor against:
4.
Power electronics deals with the control of ac power at what frequencies essentially?
6.
When fed from a fully controlled rectifier, a dc motor, driving an active load can operate in
7.
It is preferable to use a train of pulse of high frequency for gate triggering of SCR in order to reduce
8.
SCR is a rectifier constructed of silicon material. Silicon is chosen because
9.
What is the sensing element of acceleration transducer?
10.
Which is suitable for making the variable frequency drives
11.
In a thyristor, di/dt protection is achieved by the use of
12.
An SCR combines the feature of
13.
What region lies between the peak point and valley point of UJT emitter characteristic?
15.
An SCR chopper circuit supplies power to a dc motor , what will be the nature of motor armature current?
17.
R-C snubber is used in parallel with the thyristor to
18.
In a singe-phase full-wave controlled bridge rectifier, minimum output voltage and maximum output voltage are obtained at which conduction angles?
19.
The triac is equivalent to
20.
Carrier frequency gate drive is used for turn-on of a thyristor to reduce.
21.
A normally operated SCR has an anode which is _____ with respect to cathode.
22.
In a single-phase full wave regulator, the firing angles in the positive and negative half cycles are generally.
24.
A freewheeling diode in a phase-controlled rectifier
25.
What is basically a two-terminal parallel-inverse combination of semiconductor layers that permits triggering in either direction?
26.
Which is four terminal device
27.
The typical turn-off time of an SCR is about
28.
When the firing angle of SCR is increased, its output
29.
The latching current is _________ than the holding current
30.
The torque produced by a single-phase induction motor fed through an ac voltage controller for speed control is due to
31.
A thyristor can be termed as
32.
Snubber circuits are used to protect thyristor from which of the following?
33.
Once an SCR is turned on, it remains so until the anode current goes below
34.
The device commonly used for triggering a triac is
35.
Which of the following is NOT a method primarily used for density sensing?
36.
When an SCR is combined to a switch, it is considered as a switch.
37.
Which of the following is a four-layer diode with an anode gate and a cathode gate?
38.
Which one of the following statements is correct? In the case of load regulation
39.
Which terminal does not belong to the SCR?
40.
A modern power semiconductor device that combines the characteristics of BJT and MOSFET is
41.
With gate open, if the supply voltage exceeds the breakover voltage of SCR, then SCR will conduct
42.
What is a solid state equivalent of a gas filled triode?
43.
Which of the following can change the angle of conduction in SCR?
44.
When the supply voltage exceeds the breakover voltage of an SCR, it
45.
In order to get best results per unit cost, the heat sinks, on which the thyristors are mounted , are made of
47.
In a switching regulator , the control transistor is conducting
48.
In a UPS, the solid state switch normally transfer supply within
49.
A thyristor controlled reactor, the firing angle of thyristor is to be controlled in the range of
50.
Which one of the following controls reduces the size of the transformer in a switch mode ac power supply ?
