1
GATE EE 2007
MCQ (Single Correct Answer)
+2
-0.6
A single $$-$$ phase, $$230$$ $$V$$, $$50$$ $$Hz$$ $$ac$$ mains fed step down transformer $$(4:1)$$ is supplying power to a half $$-$$ wave uncontrolled $$ac$$ $$-$$ $$dc$$ converter used for charging a battery ($$12$$ $$V$$ $$dc$$) with the series current limiting resistor being $$19.04\,\Omega $$. The charging current is
A
$$3.43$$ $$A$$
B
$$1.65$$ $$A$$
C
$$1.22$$ $$A$$
D
$$1.0$$ $$A$$
2
GATE EE 2007
MCQ (Single Correct Answer)
+2
-0.6
A $$1:1$$ pulse transformer $$(PT)$$ is used to trigger the $$SCR$$ in the adjacent figure. The $$SCR$$ is rated at $$1.5$$ $$kV$$, $$250$$ $$A$$ with $${{\rm I}_L} = 250\,mA,\,\,{{\rm I}_H} = 150\,mA,$$ and $${{\rm I}_{G\max }} = 150mA$$ with $${{\rm I}_L} = 250\,mA,$$ $${{\rm I}_{G\min }} = 100mA.$$ The $$SCR$$ is connected to an inductive load, where $$L$$ $$=150$$ $$mH$$ in series with a small resistance and the supply voltage is $$200$$ $$V$$ $$dc.$$ The forward drops of all transistors/diodes and gate $$-$$ cathode junction during $$ON$$ state are $$1.0V$$

The resistance $$R$$ should be

GATE EE 2007 Power Electronics - Power Semiconductor Devices Question 5 English
A
$$4.7k\Omega $$
B
$$470k\Omega $$
C
$$47\Omega $$
D
$$4.7\Omega $$
3
GATE EE 2007
MCQ (Single Correct Answer)
+2
-0.6
A $$1:1$$ pulse transformer $$(PT)$$ is used to trigger the $$SCR$$ in the adjacent figure. The $$SCR$$ is rated at $$1.5$$ $$kV$$, $$250$$ $$A$$ with $${{\rm I}_L} = 250\,mA,\,\,{{\rm I}_H} = 150\,mA,$$ and $${{\rm I}_{G\max }} = 150mA$$ with $${{\rm I}_L} = 250\,mA,$$ $${{\rm I}_{G\min }} = 100mA.$$ The $$SCR$$ is connected to an inductive load, where $$L$$ $$=150$$ $$mH$$ in series with a small resistance and the supply voltage is $$200$$ $$V$$ $$dc.$$ The forward drops of all transistors/diodes and gate $$-$$ cathode junction during $$ON$$ state are $$1.0V$$

The minimum approximate volt $$-$$second rating of the pulse transformer suitable for triggering the $$SCR$$ should be: (Volt - second rating is the maximum of product of the voltage and the width of the pulse that may be applied)

A
$$2000\,\mu \,\,V - s$$
B
$$200\,\mu \,\,V - s$$
C
$$20\,\mu \,\,V - s$$
D
$$2\,\mu \,\,V - s$$
4
GATE EE 2007
MCQ (Single Correct Answer)
+2
-0.6
The circuit in the figure is current commutated $$dc$$ $$-$$ $$dc$$ chopper where, $$T{h_M}$$ is the main $$SCR$$ and $$T{h_AUX}$$ is the auxiliary $$SCR$$. The load current is constant at $$10$$ $$A.$$
$$T{h_M}$$ is $$ON$$
$$T{h_AUX}$$ is trigged at $$t=0.$$ $$T{h_M}$$ is turned $$OFF$$ between. GATE EE 2007 Power Electronics - Choppers and Commutation Techniques Question 7 English
A
$$0{\mkern 1mu} {\mkern 1mu} \mu s < t \le 25{\mkern 1mu} {\mkern 1mu} \mu s$$
B
$$25{\mkern 1mu} {\mkern 1mu} \mu s < t \le 50{\mkern 1mu} {\mkern 1mu} \mu s$$
C
$$50{\mkern 1mu} {\mkern 1mu} \mu s < t \le 75{\mkern 1mu} {\mkern 1mu} \mu s$$
D
$$75{\mkern 1mu} {\mkern 1mu} \mu s < t \le 100{\mkern 1mu} {\mkern 1mu} \mu s$$
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