1). a step up chopper has input voltage 150 V . the value of duty cycle is
a)
0.32
b)
0.67
c)
0.45
d)
0.27
2). Which statement is true for latching current ?
a)
it is related to turn off process of the device
b)
it is related to conduction process of device
c)
it is related to turn on process of the device
d)
both c and d
3). If the holding current of a thyristor is 2 mA then latching current should be
a)
0.01 A
b)
0.002 A
c)
0.009 A
d)
0.004 A
4). In reverse blocking mode of a thyristor
a)
junction J2 is in reverse bias and J1,J2 is in forward bias
b)
junction J3 is in forward bias and junction J1,J2 in reverse bias
c)
junction J1,J3 is in reverse bias and junction j2 is in forward bias
d)
junction J1 and J2 is in forward bias and junction j3 is in reverse bias
5). In forward blocking mode of a thyristor
a)
junction j2 is in reverse bias and J1.J3 is in forward bias
b)
junction J3 is in forward bias and J1,J2 is in reverse bias
c)
junction J1,J3 is in reverse bias and J2 is in forward bias
d)
junction J1 and J2 is in forward bias and J3 is in reverse bias
6). leakage current flows through the thyristor in
a)
forward blocking mode
b)
reverse blocking mode
c)
both forward and reverse blocking mode
d)
forward conduction mode
7). which triggering is most reliable
a)
forward voltage triggering
b)
gate triggering
c)
dV /dt triggering
d)
Thermal triggering
8). Light triggering is mainly used in
a)
low-voltage direct current transmission
b)
medium voltage direct transmission.
c)
high voltage direct current transmission
d)
all of this
9). In a P1 N1 P2 N2 thyristor which layer is less doped ?
width=176
a)
P1
b)
N1
c)
P2
d)
N2
10). SCR will be turned off when anode current is
a)
less then latching current but greater then holding current and gate signal is 0
b)
less then holding current
c)
less then latching current but greater then holding current and the gate current is present
d)
both a and b
