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SILICON CONTROLLED RECTIFIERS

Total questions: 21

Worksheet time: 19mins

Name
Class
Date
1.

Choose power switches used in controlled rectifier circuits.

a)

BJTs

b)

Diodes

c)

IGBTs

d)

Thyristors

2.

During the positive half-cycle of the supply voltage, the power switches of controlled rectifiers are automatically turn-on.

a)

True

b)

False

3.

Choose the requirements to turn-on the thyristors in a controlled full-wave rectifiers.

a)

The anode terminal of the thyristors is positive.

b)

The cathode terminal of the thyristor is positive.

c)

The half-cycle of the AC supply voltage is positive.

d)

Applying a control signal to the gate terminal of the thyristors.

4.

The function of controlled rectifiers is to vary the DC power supplied to the load.

a)

True

b)

False

5.

Under typical operation, the current conduction range of controlled rectifiers is larger than uncontrolled rectifiers.

a)

True

b)

False

6.

SCR is defined as ...............

a)

Silicone Cup Rectifier

b)

Supply Controlled Rectifier

c)

Silicone Controlled Rectifier

d)

Shorted Controlled Rectifier

7.

Which is the symbol of SCR?

a)
b)
c)
d)
8.

Terminals of SCR are ..........

a)

Anode and Cathode

b)

Collector, Base and Emitter

c)

Anode, Cathode and Gate

d)

Drain, Source and Gate

9.

Power Electronics can be defined as ...........

a)

A conversion from Alternating Current to Direct Current of Power Supply

b)

A conversion of DC power supply to AC power supply

c)

A conversion of AC power supply to AC power supply

d)

A technology of converting electric power from one supply to another supply using electronic power devices.

10.

The electronic devices below are unidirectional devices EXCEPT:

a)

TRIAC

b)

Diode

c)

Silicone Controlled Rectifier

11.

Diode pass ......... in one direction?

a)

a) Voltage

b)

b) Current

c)

c) Both

d)

d) None of these

12.
A Diode has .............
a)
two pn junction
b)
one pn junction
c)
three pn junction
d)
none of the above
13.
For an SCR in the forward blocking mode (practically)
a)
leakage current does not flow
b)
leakage current flows from anode to cathode
c)
leakage current flows from cathode to anode
d)
leakage current flows from gate to anode
14.

A silicon controlled rectifier (SCR) is a_______

a)

Unijunction device

b)

Device with three junction

c)

Device with four junction

d)

None of the above

15.

A thyristor is basically_____

a)

PNPN device

b)

A set of SCRs

c)

A combination of diac and triac

d)

A set of SCR, diac and a triac

16.

If holding current of a thyristor is 2 mA then latching current should be____

a)

0.02

b)

0.001

c)

0.004

d)

0.002

17.

SMPS is used for

a)

obtaining controlled ac power supply

b)

switch from one source to another

c)

storage of dc power

d)

obtaining controlled dc power supply

18.

To switch on SCR need ......

a)

Positive Vgt

b)

Negative Vgt

c)

Base current

d)

Collector current

19.

Which of the following statement is correct for an SCR operating in REVERSE BLOCKING MODE - practical condition

a)
leakage current flows from anode to cathode
b)
no leakage current
c)
leakage current flows from cathode to gate
d)
leakage current flows from cathode to anode
20.

Three types of common  power transistor are.....

a)
Diode, Triac and IGBT
b)
BJT, MOSFET and IGBT
c)
Diode, IGBT and GTO
d)
GTO, MOSFET and IGBT
21.

Fill in the blank . Power Electronics  circuits involve______________ from one form to another using power semiconductor devices 

a)
converting mechanical power
b)
transfer heat
c)
converting electrical power
d)
converting electromagnetic field