WorksheetsExploring Power Electronics
Total questions: 10
Worksheet time: 6mins
Thyristor is a
Current controlled device
Voltage Controlled device
Majority carrier controlled device
Minority carrier controlled device
For protection of thyristor against high dv/dt which protection circuit is used
Connecting an inductor in series with the thyristor
Connecting a series RC(Snubber) circuit across the SCR
Connecting a HRC fuse in series with the thyristor
By removing the gate supply
What does the I2*t(Amp2 -sec) rating of a thyristor specify
The energy the thyristor can withstand in forward blocking state
The energy which the thyristor can with stand before the fault is cleared
The energy which the thyristor can withstand after the fault is cleared
The power dissipated by the thyristor device
Which of the layer in a thyristor is the most lightly dopped
Outer N layer
Outer P layer
Inner P layer
Inner N layer
The reliability of a series connected SCR string is 60 percent , then the string efficiency will be
30 %
100%
40%
10%
Find the turn off time(milli sec) of a thyristor used as a Half wave controlled rectifier feeding resistive load. The AC supply frequency is 50 Hz
10 milli sec
20 milli sec
5 millisec
2.5 millisec
A resistive load of 10 ohm is fed from a 3 phase half wave controlled rectifier. The firing angle alpha is less equal to 6π . The per phase rms value of the supply votage is 230V. The average output voltage is
189.66V
192V
100V
250V
The turn off time for converter grade thyristor is
between 10 to 30 μ sec
Less than 10 μ sec
between 40 to 80 μ sec
between 40 to 100 nanoseconds
The main disadvantage of presence of source inductance in a single phase controlled AC-DC rectifier
Average output voltage decreases
Average output voltage remains same
Average output voltage increases
The firing angle increases
The thyristor is an
fully controlled switch
un controlled switch
manual switch
semi controlled switch
