This set of FACTS Multiple Choice Questions & Answers (MCQs) focuses on “Functions of FACTS Controllers”.
1. Match the following.
| FACTS devices | Response |
|---|---|
| A) STATCOM | i) Slow |
| B) Synchronous Condenser | ii) Fast |
| C) Thyristor Switched Capacitor | iii) Faster |
| D) Thyristor Controlled Reactor | iv) Fastest |
a) A-iv, B-ii, C-iii, D-i
b) A-i, B-ii, C-iv, D-iii
c) A-iii, B-ii, C-i, D-iv
d) A-iv, B-i, C-ii, D-iii
View Answer
Explanation: On comparing these four devices, Synchronous condenser, TSC, TCR and STATCOM; we find the following comparison chart with respect to their responses.
| FACTS devices | Response |
|---|---|
| Synchronous Condenser | Slow |
| Thyristor Switched Capacitor [TSC] | Fast |
| Thyristor Controlled Reactor [TSR] | Faster |
| Static Synchronous Compensator [STATCOM] | Fastest |
2. The losses inside a packaged power electronic circuit with silicon wafer inside, is insignificant.
a) True
b) False
View Answer
Explanation: The losses inside a packaged power electronic circuit with silicon wafer inside, plays a significant role. These losses come in the form of heat. So proper design is required to extract the heat from inside the packaged circuit. This is done to ensure that temperature of the wafer does not surpass the safe level for proper operation. Higher losses imply higher cost of packaging.
3. Packaging and cooling are insignificant in power electronic circuit fabrication with silicon wafer inside.
a) True
b) False
View Answer
Explanation: Packaging and cooling are very much significant in power electronic circuit fabrication with silicon wafer inside. Generally power electronic circuit with silicon wafer inside are sealed and packaged with high-voltage- insulation. Accordingly proper cooling arrangements are essential to extract the heat from inside to the external cooling medium as per the design/fabrication.
4. Power electronics employed in FACTS converters are operated exceeding the safe temperature limit.
a) True
b) False
View Answer
Explanation: Power electronics employed in FACTS converters CANNOT BE operated exceeding the safe temperature limit. This is because the devices/circuits are designed to operate with safe switching characteristics up to its designed safe temperature limit. In no way the silicon wafer temperature which is the building block/base of Power Semiconductor Devices; should exceed the safe operating limit which is about 100°C.
5. Power electronics employed in FACTS converters are designed with adequate margin for the overload and short circuit currents.
a) True
b) False
View Answer
Explanation: Power electronics employed in FACTS converters are designed with adequate margin for the overload and short circuit currents. Almost always, fault current dictates the normal useable rating of the power electronic circuits. This is done to ensure that temperature of the inside silicon wafer does not surpass the safe level for proper operation.
6. In FACTS, SOA stands for ________
a) silicon operation area
b) safe operating antena
c) silicon operated amplifier
d) safe operating area
View Answer
Explanation: In FACTS, SOA stands for safe operating area. Every Power electronic device has its characteristic turn-on and turn-off capability. This defines its safe operating area which indicates the safe operating zone of the power device.
7. SOA is found out from ________
a) P-t characteristics graph
b) I-t characteristics graph
c) V-I characteristics graph
d) V-t characteristics graph
View Answer
Explanation: SOA is found out from V-I characteristics graph of the device concerned. On plotting the V-I characteristics graph of the device with its permissible voltage and current limit, SOA can easily be traced out. SOA defines safe switching characteristics.
8. The device performance of converters would be better if those devices, gate-drive circuits, snubber circuits, etc. are sold separately.
a) True
b) False
View Answer
Explanation: The device performance of converters would be inferior if those devices, gate-drive circuits, snubber circuits, etc. are sold separately than together in assembly modules. Actually the gate- drivers, snubbers, and the devices when assembled into a converter-module, the related bus-work for connecting them are proximity to the devices. Thus the packaging cost of individual circuits and associated losses, switching speed and sizes are optimized which improve the device performance of converter-modules.
9. The process of fabrication of power electronic devices is only about doping of silicon wafer with different impurities.
a) True
b) False
View Answer
Explanation: The process of fabrication of power electronic devices is NOT only about doping of silicon wafer with different impurities. It is true that doping is of key importance to fabrication of power electronic devices, including the levels and shapes of doping. But the whole process employs the advanced technologies of photolithography, laser cutting, etching, padding with insulation, and proper packaging,
10. GTO employs ________
a) double-sided cooling and thin packaging technology
b) double-sided cooling and thick packaging technology
c) single-sided cooling and thin packaging technology
d) single-sided cooling and thick packaging technology
View Answer
Explanation: GTO employs double-sided cooling and thin packaging technology. This is done to achieve efficient removal of heat from the GTO. This in turn enhances the performance of GTO.
11. MTO employs no transistor in its construction.
a) True
b) False
View Answer
Explanation: MTO does employ transistors in its construction. MTO utilizes both npn transistor and pnp transistor in its functional structure. For turning-on MTO, both npn transistor and pnp transistor come into play.
12. MTO uses transistors for turning-on and MOSFETs for turning-off itself.
a) True
b) False
View Answer
Explanation: MTO uses transistors for turning-on and MOSFETs for turning-off itself. Actually it uses both npn and pnp transistors for its turning-on. By shorting the emitter and base of the npn transistor, MOSFET effectively turns-off MTO.
13. GTO and MTO utilize the same principle for their turning-off activities.
a) True
b) False
View Answer
Explanation: GTO and MTO do not utilize the same principle for their turning-off activities. The npn transistor takes part in turning-off process of both GTO and MTO. MTO shorts the emitter and base of the npn transistor, GTO sweeps away enough current out of the emitter base of the npn transistor.
14. PEBB stands for ________
a) Power Electronics Building Block
b) Power Emitter Building Block
c) Power Electronics Building Bridge
d) Powerless Electronics Building Block
View Answer
Explanation: PEBB stands for Power Electronics Building Block. It indicates the concept to integrate the gate-drive circuits. Thus it reduces requirements of gate-drive circuits and helps to achieve fast switching of the devices.
15. The residual charge on the anode side during turning-off of the thyristor devices causes a delay in turning-on.
a) True
b) False
View Answer
Explanation: The residual charge on the anode side during turning-off of the thyristor devices causes a delay in turning-on. It is reflected in the characteristic graph where the next turn-on cycle has to wait till the long turn-off tail at the end of its preceding turnoff cycle does not vanish. This attributes to the dissipation of residual charge on the anode side through recombination process.
Sanfoundry Global Education & Learning Series – Flexible AC Transmission System (FACTS).
To practice all areas of Flexible AC Transmission System (FACTS), here is complete set of 1000+ Multiple Choice Questions and Answers.
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