Year 2023

Week # 4 Quiz 1

Q1. two's complement of a binary number 1010 is

Q2. 3 - phase voltage source inverter is operated in 180° conduction mode. Which one of the following statements is true?

Q3. A dc voltage source of 250 V is supplying R-L load through an SCR and latching current for an SCR  is 130 mA . Compute the minimum rate of width pulse required to turn ON the SCR in case load consists of R = 25 \(\Omega\) in series with L = 0.5 H.

Q4. A 220 V DC supply is connected to a DC chopper which is operating on TRC control mode at a frequecy of 5 kHz. When the output is 110 V, the ON and OFF period of each cycle are respectively

Q5. A thyristor has thermal resistance is 1.8 °C/W and the maximum allowable internal power dissipation is 50 W. If the ambient temperature is 40 °C, the maximum allowable Junction temperature is

Q6. A dc voltage source of 200 V is supplying R-L load through an SCR with pulse width of \(150 \mu s\). Compute the latching current of SCR in case load consists of R = 50 \(\Omega\) in series with L = 0.5 H.

Q7. Assertion (A): Inverters and choppers use fast-switching thyristors
Reason (R): Fast-switching SCR has a low turn-off time.

Q8. 5 thyristors rated 200 V in series. The operating voltage of the string is 900 V. Derating factor of the string is

Q9. A single phase AC voltage controller is controlling current in a purely inductive load. If the firing angle of SCR is \(\alpha\), what will be the conduction angle of the SCR?

Q10. Which of the following diode has the least reverse recovery time?