21. Calculate the value of the Input power factor using the data: Fundamental displacement factor=.96, Distortion factor=.97.
A. .93
B. .84
C. .48
D. .89
Answer: A
The value of the input power factor is a product of the (Fundamental displacement factor)×(Distortion factor)
=g×F.D.F=.97×.96=.93.
22. Displacement factor depends upon the shape of the waveform.
A. True
B. False
Answer: A
The displacement factor depends upon the shape of the waveform. The displacement factor is the cosine of the angle between the fundamental voltage and fundamental current. It depends upon the type of load and converter type.
23. In single-phase RLE load, calculate the voltage across the thyristor when current decays to zero using the data: (Vs)r.m.s=340 V, f=50 Hz, R=2 Ω, E=150 V, β=160°.
A. 45.89 V
B. 74.45 V
C. 54.85 V
D. 84.48 V
Answer: B
In a single-phase RLE load the voltage across the thyristor when the current decays to zero
VT=Vmsin(β)-E
=340×√2sin(160°)-90=74.45 V.
24. In single-phase RLE load, calculate the angle at which conduction starts using the data: (Vs)=14sin(Ωt), f=50 Hz, E=10 V.
A. 45.58°
B. 46.26°
C. 47.26°
D. 49.56°
Answer: A
The angle at which conduction starts when Vmsin(θ)=E. The conduction will remain from ϴ to π-θ.
Θ=sin-(E÷Vm)
=sin-(.71)=45.58°.
25. Full form of PIV.
A. Peak inverse voltage
B. Peak insert voltage
C. Paas Inverse volatile
D. Peak insert volatile
Answer: A
PIV stands for Peak inverse voltage. It is the maximum negative voltage after which the thyristor will break down.
26. Calculate the PIV for the Full-wave bridge rectifier if the peak value of the supply voltage is 230.
A. 324.4 V
B. 325.2 V
C. 524.4 V
D. 626.8 V
Answer: A
The peak inverse voltage for the Full-wave bridge rectifier is
Vm=√2×230=325.2 V.
The peak inverse is the maximum negative voltage across the thyristor.
27. In single-phase RLE load, calculate the Peak inverse voltage using the data: (Vs)r.m.s=89 V, f=50 Hz, E=440 V.
A. 521.2 V
B. 527.8 V
C. 597 V
D. 529 V
Answer: C
In a single-phase, RLE load the peak inverse voltage across the thyristor VT=Vm+E=529 V.
28. Full form of DAC is ___________
A. Digital to Analog converter
B. Discrete to Analog converter
C. Digital to AC converter
D. Discrete to Avalanche converter
Answer: A
DAC stands for Digital to Analog converter. It converts the digital signal to an analog signal. It is used in microcontrollers and microprocessors.
29. Full form of ADC is ___________
A. Analog to Digital converter
B. Discrete to Analog converter
C. Analog to Digital converter
D. Discrete to Avalanche converter
Answer: C
ADC stands for Analog to Discrete converter. It converts the analog signal to a discrete signal. It is used in microcontrollers and microprocessors.
