A step-down chopper operates from a DC voltage source Vs and feeds a DC motor armature with counter emf Eb. From oscilloscope traces it is found that current increases for time tr, falls to zero over a time tf and remains zero for a time t0 in every chopping cycle. Then the average voltage across the motor would be

Question

A step-down chopper operates from a DC voltage source Vs and feeds a DC motor armature with counter emf Eb. From oscilloscope traces it is found that current increases for time tr, falls to zero over a time tf and remains zero for a time t0 in every chopping cycle. Then the average voltage across the motor would be

TuteeHUB · Accepted Answer

$\frac{{{V}_{s}}{{t}_{r}}+{{E}_{b}}\left( {{t}_{f}}+{{t}_{0}} \right)}{{{t}_{r}}+{{t}_{f}}+{{t}_{0}}}$

TuteeHUB · Answer

$\frac{{{V}_{s}}{{t}_{r}}}{{{t}_{r}}+{{t}_{f}}+{{t}_{0}}}$

TuteeHUB · Answer

$\frac{{{V}_{s}}{{t}_{c}}+{{E}_{b}}{{t}_{f}}}{{{t}_{r}}+{{t}_{f}}+{{t}_{0}}}$

TuteeHUB · Answer

$\frac{{{V}_{s}}{{t}_{r}}+{{E}_{b}}{{t}_{0}}}{{{t}_{r}}+{{t}_{f}}+{{t}_{0}}}$

1.	A step-down chopper operates from a DC voltage source Vs and feeds a DC motor armature with counter emf Eb. From oscilloscope traces it is found that current increases for time tr, falls to zero over a time tf and remains zero for a time t0 in every chopping cycle. Then the average voltage across the motor would be
A.	\(\frac{{{V}_{s}}{{t}_{r}}}{{{t}_{r}}+{{t}_{f}}+{{t}_{0}}}\)
B.	\(\frac{{{V}_{s}}{{t}_{c}}+{{E}_{b}}{{t}_{f}}}{{{t}_{r}}+{{t}_{f}}+{{t}_{0}}}\)
C.	\(\frac{{{V}_{s}}{{t}_{r}}+{{E}_{b}}{{t}_{0}}}{{{t}_{r}}+{{t}_{f}}+{{t}_{0}}}\)
D.	\(\frac{{{V}_{s}}{{t}_{r}}+{{E}_{b}}\left( {{t}_{f}}+{{t}_{0}} \right)}{{{t}_{r}}+{{t}_{f}}+{{t}_{0}}}\)
Answer» D. \(\frac{{{V}_{s}}{{t}_{r}}+{{E}_{b}}\left( {{t}_{f}}+{{t}_{0}} \right)}{{{t}_{r}}+{{t}_{f}}+{{t}_{0}}}\)

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