MCQOPTIONS
Saved Bookmarks
MCQOPTIONS
This section includes 12 Mcqs, each offering curated multiple-choice questions to sharpen your Power Electronics knowledge and support exam preparation. Choose a topic below to get started.
| 1. |
Thyristors are used in electronic crowbar protection circuits because it possesses |
| A. | high surge current capabilities |
| B. | high amp 2-sec rating |
| C. | less switching losses |
| D. | voltage clamping properties |
| Answer» B. high amp 2-sec rating | |
| 2. |
The thyristor has the following specificationsVs = 400 V(di/dt)max = 25 A/μsecFind the value of L |
| A. | 8 μH |
| B. | 80 μH |
| C. | 16 μH |
| D. | 160 μH |
| Answer» D. 160 μH | |
| 3. |
False triggering of the SCRs by varying flux & noise is avoided by using |
| A. | F.A.C.L.F & C.B |
| B. | Shielded cables & twisted gate leads |
| C. | Snubber circuits |
| D. | di/dt inductor in series with the gate terminal |
| Answer» C. Snubber circuits | |
| 4. |
Figure below shows SCR having dv/dt and di/dt protection, when the switch(shown in green) is closed the current through Rl = |
| A. | I(1 – e-t/τ) |
| B. | I(1 + e-t/τ) |
| C. | I(1 – et/τ) |
| D. | I(1 + e-t/τ) |
| Answer» B. I(1 + e-t/τ) | |
| 5. |
Thyristors_are_used_in_electronic_crowbar_protection_circuits_because_it_possesses$ |
| A. | high surge current capabilities |
| B. | high amp <sup>2</sup>-sec rating |
| C. | less switching losses |
| D. | voltage clamping properties |
| Answer» B. high amp <sup>2</sup>-sec rating | |
| 6. |
False triggering of the SCRs by varying flux & noise is avoided by usin? |
| A. | F.A.C.L.F & C.B |
| B. | Shielded cables & twisted gate leads |
| C. | Snubber circuits |
| D. | di/dt inductor in series with the gate terminal |
| Answer» C. Snubber circuits | |
| 7. |
Over-current protection in SCRs is achieved through the use of |
| A. | Varistors |
| B. | Snubber Circuits |
| C. | F.A.C.L.F & C.B. |
| D. | Zener diodes |
| Answer» D. Zener diodes | |
| 8. |
The effect of over-voltages on SCR are minimized by using |
| A. | RL circuits |
| B. | Circuit breakers |
| C. | Varistors |
| D. | di/dt inductor |
| Answer» D. di/dt inductor | |
| 9. |
dv/dt protection is provided to the SCR by |
| A. | connecting a capacitor in parallel with the load |
| B. | connecting an inductor in series with the load |
| C. | connecting a capacitor & resister in parallel with the device |
| D. | connecting an inductor & resister in parallel with the device |
| Answer» D. connecting an inductor & resister in parallel with the device | |
| 10. |
The dv/dt protection is provided in order to |
| A. | limit the power loss |
| B. | reduce the junction temperature |
| C. | avoid accidental turn-on of the device |
| D. | avoiding sudden large voltage across the load |
| Answer» D. avoiding sudden large voltage across the load | |
| 11. |
The local hot spot formation in the cross-section of the SCR is avoided by |
| A. | reducing the junction temperature |
| B. | applying gate current nearer to the maximum gate current |
| C. | using only R loads |
| D. | proper mounting of the SCR on heat sink |
| Answer» C. using only R loads | |
| 12. |
di/dt protection is provided to the thryistor by |
| A. | connecting an inductor in parallel across the load |
| B. | connecting an inductor in series with the load |
| C. | connecting an inductor in parallel across the gate terminal |
| D. | connecting an inductor in series with the gate |
| Answer» C. connecting an inductor in parallel across the gate terminal | |