POWER ELECTRONICS AND DRIVES PART 17

POWER ELECTRONICS AND DRIVES PART 17

1. The GTO (gate turn-off thyristor) is a
a) p-n-p-n device
b) p-n-p device
c) p-metal-n device
d) p-n single junction device
 

Answer: a
 
2. The GTO can be turned off
a) by a positive gate pulse
b) by a negative gate pulse
c) by a negative anode-cathode voltage
d) by removing the gate pulse
 

Answer: b

3. The anode current is ideally limited by the
a) gate pulse amplitude
b) internal impedance of the device
c) load Impedance
d) gate circuit impedance
 
Answer: c

4. In a GTO the n+ layer forms the
a) anode & gate
b) cathode & gate
c) cathode
d) gate
 
Answer: c

5. The turn-off gain βoff of the GTO is given by
a) Ig/Ia
b) Ia/Ig
c) Vg/Va
d) Vg/Va
 
Answer: b

6. A GTO can be represented by two transistors T1 & T2. The current gain of both transistors are α1 and α2 respectively. A low value of gate current requires
a) low value of α1 and α2
b) low value of α1 and high value of α2
c) high value of α1 and low value of α2
d) high values of α1 and α2
 
Answer: b

7. Gold doped GTOs have _____________ as compared to the conventional GTOs
a) high turn-off time
b) low negative gate current requirement
c) low reverse voltage blocking capabilities
d) lower positive gate current requirement
 
Answer: b

8. Latching current for the GTOs is ________ as compared to CTs (Conventional thyristors).
a) more
b) less
c) constant
d) cannot be said
 
Answer: a

9. In case of the two-transistor model (T1 & T2) of GTO with anode-short, the anode-short is placed between the
a) emitter of T1 & T2
b) emitter of T1 & base of T2
c) emitter of T1 & base of T1
d) emitter of T1 & collector of T2
 
Answer: c

10. Choose the correct statement:
GTOs have _________ as compared to the CTs.
a) less on-state voltage drop
b) less gate drive losses
c) higher reverse blocking capabilities
d) faster switching speed
 
Answer: d