131. Calculate the line voltage for 3-∅ 120° VSI if the value of the DC supply is 24 V.
A. 16.52 V
B. 16.97 V
C. 12.96 V
D. 12.48 V
Answer: B
The line voltage for 3-∅ 120° VSI is
(VDC÷√2)
= .707×24 = 16.97 V.
In 3-phase 120° VSI each phase conducts for 120° and only three switches from different phases conduct at a single time.
132. Calculate the phase voltage for 3-∅ 120° VSI if the value of DC supply is 26 V.
A. 10.52 V
B. 10.97 V
C. 10.96 V
D. 10.61 V
Answer: D
The line voltage for 3-∅ 120° VSI is (VDC÷√6) = 10.61 V.
In 3-phase 120° VSI each phase conducts for 120° and only three switches from different phases conduct at a single time.
133. Calculate power absorbed by 5 Ω load in 3-∅ 120° VSI if the value of DC supply is 16 V.
A. 17.06 W
B. 15.15 W
C. 18.25 W
D. 19.26 W
Answer: A
The power absorbed by 5 Ω load in 3-∅ 120° VSI if the value of DC supply is 16 V is
Vph2÷R = (16÷√3)2÷5 = 17.06 W.
134. Calculate power absorbed by 10 Ω load in 3-∅ 180° VSI if the value of DC supply is 36 V.
A. 20.6 W
B. 24.5 W
C. 26.4 W
D. 28.8 W
Answer: D
The power absorbed by 10 Ω load in 3-∅ 180° VSI if the value of DC supply is 36 V is
Vph2÷R = (22.6÷3)2÷10 = 28.8 W.
135. T.H.D value for 3-∅ 180° VSI is ________
A. 36 %
B. 31 %
C. 39 %
D. 46 %
Answer: B
T.H.D value for 3-∅ 180° VSI is 31 %. Triple harmonics are absent in 3-∅ 180° VSI and 3-∅ 120° VSI. Only 6k±1 harmonics are present.
136. Rectifiers are used to convert DC power into variable AC power.
A. True
B. False
Answer: B
Inverters are used to convert DC power into variable AC power. The variable AC power means variable frequency and variable voltage level.
137. The short circuit problem is severe in the case of the current source inverter.
A. True
B. False
Answer: B
Short-circuit problem is severe in the case of voltage source inverter. The output voltage of VSI is fixed but the output current depends upon the load. When Z = 0, I = V÷Z = ∞.
138. Full form of KERS is ___________
A. The kinetic energy recovery system
B. The kinetic ever recovery system
C. Kin ever recovery system
D. The kinetic energy recovery store
Answer: A
The full form of KERS is the Kinetic energy recovery system. The systems recover the kinetic energy from the heat generated by the car’s braking.
139. Full form of IGBT is ___________
A. Insulated gate bipolar transistor
B. Insulated gate bipolar transducer
C. Insulator gate bidirectional transducer
D. Insulated gate bidirectional transistor
Answer: A
The full form of IGBT is an Insulated gate bipolar transistor. It is a 3-terminal device, bipolar in nature. It can be used as a switch.
140. Flywheel is analogous to ___________
A. Chemical battery
B. Mechanical battery
C. Nuclear battery
D. Electrostatic battery
Answer: B
A flywheel is a heavy wheel that stores a high amount of rotational kinetic energy. It requires a lot of force to spin the wheel.