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.Management Sciences
Category: Power Electronics
If all the SCR’s of 3 phase PAC is replaced by diodes, they would be triggered_____________?
A. 120 degree after the zero crossing of the corresponding line voltages
B. 60 degree after the zero crossing of the corresponding line voltages
C. 120 degree before the zero crossing of the corresponding line voltages
D. 60 degree before the zero crossing of the corresponding line voltages
Electrical power output in a d.c. generator is equal to____________?
A. Electrical power developed in armature – copper losses
B. Mechanical power input – iron and friction losses
C. Electrical power developed in armature – iron and copper losses
D. Mechanical power input – iron and friction losses – copper losses
Spread time is defined as the interval during which_____________?
A. anode voltage drops from 10 % of its initial value to zero
B. anode current rises from 90 % to its final value
C. both (A) and (B)
D. anode current rises from 10 % to 90 % of its final value
The input current waveform of a bridge controlled rectifier when the load is perfectly filtered is___________?
A. Sine wave
B. Square wave
C. Saw – tooth wave
D. Trapezoidal wave
Voltage commutation circuit can be converted into a current commutation by interchanging the positions of____________?
A. Diode and capacitor
B. Capacitor and SCR
C. Inductor and capacitor
D. Capacitor and load
A carrier based PWM technique in CSI is composed of____________?
A. A switching pulse generator and a shorting pulse generator
B. A shorting pulse distributor
C. A switching and shorting pulse combination
D. All of these
In rectifiers, load current flow is_________?
A. Unidirectional
B. Bidirectional
C. Either (a) or (b)
D. Non directional
Thyristor is nothing but a____________?
A. Controlled transistor
B. Controlled switch
C. Amplifier with higher gain
D. Amplifier with large current gain
The switching function of semiconductor devices can be characterized with____________?
A. Duty ratio only
B. Frequency only
C. Duty ratio and frequency
D. Duty ratio, frequency and time delay
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