This set of FACTS Multiple Choice Questions & Answers (MCQs) focuses on “Types of Power Electronic Devices”.
1. Identify the given figure.
a) p-channel field effect transistor
b) n-channel field effect transistor
c) pnp transistor
d) npn transistor
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Explanation: The given figure shows a p-channel field effect transistor. The terminal C in the given figure is the source. This ohmic electrical connection can be at either end of the device. The direction of the arrow on the terminal A decides whether the given JFET is p-channel or n-channel.
2. Identify the terminal C of the given figure.
a) Source
b) Collector
c) Drain
d) Gate
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Explanation: The given figure shows a MOSFET. The terminal C in the given figure is the source. The direction of the arrow on the terminal C decides whether the given MOSFET is p-channel or n-channel.
3. Identify the terminal B of the given figure.
a) Source
b) Collector
c) Drain
d) Gate
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Explanation: The given figure shows a p-channel MOSFET. The terminal B in the given figure is the drain. Current flows from source to the drain.
4. Identify the terminal A of the given figure.
a) Source
b) Collector
c) Drain
d) Gate
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Explanation: The given figure shows an enhancement type MOSFET. The terminal A in the given figure is the gate terminal. Voltages applied to this gate terminal controls the conductivity through the channel of MOSFET.
5. Identify the terminal C of the given figure.
a) Source
b) Collector
c) Drain
d) Gate
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Explanation: The given figure shows an n-channel MOSFET. The terminal C in the given figure is the source. The source material here is n-type while the material of channel is p-type.
6. SUS stands for ________
a) Silicon Unijunction Switch
b) Silicon Unipolar Switch
c) Silicon Unilateral Switch
d) Silicon Unijunction Switch
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Explanation: SUS stands for Silicon Unilateral Transistor. Its structure of four layers ʻpnpnʼ is same to that of a PUT with its gate connected to n-terminal. However an avalanche diode is connected between the gate and the connected n-terminal, unlike that in a PUT.
7. PIV is an acronym for ________
a) Peak Inverse Voltage
b) Positive Inverse Voltage
c) Peak Integrated Voltage
d) Peak Inverted Voltmeter
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Explanation: PIV is an acronym for Peak Inverse Voltage. It the characteristic feature of a power diode. PIV gives an idea about the safe allowable limits of the power diode in case of any undesirable reverse voltage across it.
8. PIV is the ________ voltage that a diode can withstand.
a) largest reverse
b) largest forward
c) smallest reverse
d) smallest forward
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Explanation: PIV is the largest voltage that a diode can withstand. Any value of reverse voltage above of PIV will damage the diode permanently. Hence while incorporating a diode, the designer takes care of the fact that worst case reverse voltage should always be within the allowable limit set by PIV of the diode.
9. MOSFET is suitable for ________
a) only low voltages
b) only high voltages
c) both low voltages and high voltages
d) neither low voltages nor high voltages
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Explanation: The MOSFET, a type of transistor is suitable for only low voltages. MOSFET inherently comes with with very fast turning-on and turning-off ability. So it is often used as a pilot gate device for thyristors.
10. Choose the right option among the alternatives – A transistor conducts in its forward direction when its collector/emitter/base, is positive with respect to its collector/emitter/base, and when a turn-on voltage or current signal is applied to its collector/emitter/base.
a) Collector, base, emitter
b) Emitter, collector, base
c) Base, collector, emitter
d) Collector, emitter, base
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Explanation: A transistor conducts in its forward direction when its collector, is positive with respect to its emitter, and when a turn-on voltage or current signal is applied to its base. However, even if the base voltage or current is less than what is desired for its full turning-on of the base terminal, it will conduct but with holding partial anode to cathode voltage. There are various configurations and different types of transistors which finds application in power electronics.
11. Choose the right option among the alternatives – A thyristor goes into full conduction in its forward direction when anode/cathode/gate is positive with respect to its anode/cathode/gate and a turn-on voltage or current signal in the form of a pulse is given to its anode/ cathode/gate.
a) Cathode, anode, gate
b) Gate, anode, cathode
c) Anode, cathode, gate
d) Anode, gate, cathode
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Explanation: A thyristor goes into full conduction in its forward direction when anode is positive with respect to its cathode and a turn-on voltage or current signal in the form of a pulse is given to its gate. Some thyristors are designed without gate-controlled turn-off capability; while some thyristors are designed with both gate-controlled turn-on and turn-off capability. However, gate-controlled turning-on is their inherent property.
12. The thyristor may be designed to block in ________
a) both the forward and reverse directions
b) only forward direction
c) only reverse direction
d) neither forward nor reverse direction
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Explanation: The thyristor may be designed to block in both the forward and reverse directions. When the thyristor is designed to block only in the forward direction, it is termed as an asymmetrical device. When the thyristor is designed to block in both the forward and reverse directions, it is known as a symmetrical device.
13. SCR stands for ________
a) Silicon Converted Rectifier
b) Silicon Controlled Rectifier
c) Side Controlled Rectifier
d) Silicon Commuted Rectifier
View Answer
Explanation: SCR stands for Silicon Controlled Rectifier. The terms ʻSilicon Controlled Rectifierʼ and ʻthyristorʼ are used interchangeably. Both of them denote the basic electronic devices with four-layer pnpn configuration. In SCR turning-on and turning-off depends on regenerative feedback displayed by the pnpn layers.
14. ETO uses low voltage ________ to assist itself in turning-off.
a) transistors
b) diodes
c) resistors
d) capacitors
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Explanation: ETO uses low voltage transistors to assist itself in turning-off. ETO incorporates transistors in series with a high voltage GTO to achieve fast turning-off ability. Also transistor thus empowers ETO with low turning-off switching losses.
15. PUT stands for ________
a) Programmable Unijunction Transistor
b) Programmable Unipolar Transistor
c) Positive Unijunction Transistor
d) Programmable Unijunction Transducer
View Answer
Explanation: PUT stands for Programmable Unijunction Transistor. Its structure of four layers ʻpnpnʼ is same to that of an SCR. However its gate is connected to n-terminal, unlike that in a SCR.
Sanfoundry Global Education & Learning Series – Flexible AC Transmission System (FACTS).
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