261. In bipolar modulation, the carrier is symmetric about zero with amplitude equal to Cm, the PWM output
A. Zero
B. Switches between – 1 / 2 and + 1 / 2
C. Switches between – 1 and + 1
D. Switches between 0 and + 1

262. In the operation and control of both naturally commutated and forced commutated SCR base converter, commutation plays an important role. The converters is / are ___________?
A. AC – DC
B. DC – DC
C. DC – AC
D. All of these

263. Double Fourier series analysis of PWM is_____________?
A. Two dimensional functions
B. Three dimensional functions
C. One dimensional functions
D. All of these

264. In commutation PAC stands for_______?
A. Permanent angle converter
B. Phase angle converter
C. Phase angle commutation
D. Phase and commutation

265. In single phase VSI, the harmonic which is not present is____________?
A. 2nd
B. 3rd
C. 5th
D. 7th

266. Any electrical signal present in a circuit other than the desired signal is known as______________?
A. Noise
B. Distortion
C. Interference
D. All of these

267. Very large values of modulation index (greater than 3.24) lead to___________?
A. Square AC output voltage
B. Sine AC output voltage
C. Triangular AC output voltage
D. Trapezoidal AC output voltage

268. The man made noise sources is / are_____________?
A. Motors
B. Switches, radio interferences
C. Computers, digital electronics
D. All of these

269. Single phase VSI are mainly used in___________?
A. Power supplies
B. Ups
C. Multilevel configuration
D. All of these

270. Due to non sinusoidal waveform of the input current, the power factor of the rectifier is____________?
A. Negatively affected by firing angle
B. Negatively affected by distortion of the input current
C. Positively affected by both firing angle and distortion of the input current
D. Both (a) and (b)

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