Thyristor Chopper Circuits MCQ Quiz in বাংলা - Objective Question with Answer for Thyristor Chopper Circuits - বিনামূল্যে ডাউনলোড করুন [PDF]
Last updated on Mar 16, 2025
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Thyristor Chopper Circuits Question 1:
A current commutated chopper is fed from a dc source of 230 V, its commutating components are L = 20 μH and C = 50 μF. If load current of 200 A is assumed constant during the commutation process, the Turn – off time of main thyristor is_______ (in μ sec)
Answer (Detailed Solution Below) 62.4 - 62.7
Thyristor Chopper Circuits Question 1 Detailed Solution
\({I_{{C_P}}} = {V_S}\sqrt {\frac{C}{L}}\)
\(= 230\sqrt {\frac{{50 \times {{10}^{ - 6}}}}{{20 \times {{10}^{ - 6}}}}} = 363.66\;A\)
\(x = \frac{{{I_{CP}}}}{{{I_o}}} = 1.82\)
Turn – off time of main SCR,
\({t_C} = \left[ {\pi - 2\;{{\sin }^{ - 1}}\left( {\frac{1}{x}} \right)} \right]\sqrt {LC}\)
\(= \pi - 2\;{\sin ^{ - 1}}\left( {\frac{1}{{1.82}}} \right)\)
= 62.55 μ sec
Thyristor Chopper Circuits Question 2:
A voltage commutated chopper has the following parameters \({V_S} = 230\;V\), load circuit parameters = 0.5 Ω, 2.5 mH, 45 V. Commutation circuit parameters:
L = 10 μH and C = 40 μF
Ton = 800 μ sec, T = 2000 μ sec.
For a constant load current of 100 A. The turn off time for main thyristor and auxiliary thyristor respectively are –
Answer (Detailed Solution Below)
92 μs, 31.42 μs
Thyristor Chopper Circuits Question 2 Detailed Solution
For main thyristor \({T_1},\;{t_c} = \frac{{C{V_S}}}{{{I_o}}} = \frac{{40 \times {{10}^{ - 6}} \times 230}}{{100}}\)
For auxiliary thyristor TA, \({t_{{c_1}}} = \frac{\pi }{2}\sqrt {LC} = \frac{\pi }{2}\sqrt {10 \times 40} = 31.42\;\mu s\)
Thyristor Chopper Circuits Question 3:
In the chopper circuit shown, the main thyristor (TM) is operated at a duty ratio of 0.8. Which is much larger than the commutation interval. If the maximum allowable reapplied dv/dt on TM is 50 V/μs, what should be the theoretical minimum value of C1? Assume current ripple through L0 to be negligible.
Answer (Detailed Solution Below)
Thyristor Chopper Circuits Question 3 Detailed Solution
V0= d Vs = 80 V , \(\frac{{dv}}{{dt}} = 50V/\mu sec\)
\(\begin{array}{l} {i_0} = \frac{{80}}{8} = 10A\\ i = C\frac{{dv}}{{dt}} \Rightarrow C = 0.2\mu F \end{array}\)
Thyristor Chopper Circuits Question 4:
The circuit in the figure is current commutated dc-dc chopper where ThMis the main SCR and ThAuxis the auxiliary SCR. The load current is constant at 10 A. ThM is ON.ThAux is triggered at t = 0, ThM is turned off between
Answer (Detailed Solution Below)
Thyristor Chopper Circuits Question 4 Detailed Solution
Whenever ThAuxis triggered, it conducts for sec.
\(\pi \sqrt {LC} = 50\ \mu sec\)
During this time ThM will carry only load current. After this ThM gets off.