1
GATE EE 2008
MCQ (Single Correct Answer)
+2
-0.6
The core of two-winding transformer is subjected to a magnetic flux variation as indicated in the figure. GATE EE 2008 Electrical Machines - Transformers Question 17 English 1 GATE EE 2008 Electrical Machines - Transformers Question 17 English 2

The induced $$emf$$ $$\left( {{e_{rs}}} \right)$$ in the secondary winding as a function of time will be of the form

A
GATE EE 2008 Electrical Machines - Transformers Question 17 English Option 1
B
GATE EE 2008 Electrical Machines - Transformers Question 17 English Option 2
C
GATE EE 2008 Electrical Machines - Transformers Question 17 English Option 3
D
GATE EE 2008 Electrical Machines - Transformers Question 17 English Option 4
2
GATE EE 2007
MCQ (Single Correct Answer)
+2
-0.6
A single-phase $$50$$ $$kVA,$$ $$250$$ $$V/500V$$ two winding transformer has an efficiency of $$95\% $$ at full load, unity power factor. If it is reconfigured as a $$500V/750V$$ auto-transformer, its efficiency at its new rated load at unity power factor will be
A
$$95.752\% $$
B
$$97.851\% $$
C
$$98.276\% $$
D
$$99.241\% $$
3
GATE EE 2006
MCQ (Single Correct Answer)
+2
-0.6
A $$300$$ $$kVA$$ transformer has $$95\% $$ efficiency at full load $$0.8$$ $$pf$$ lagging and $$96\% $$ efficiency at half load, unity $$pf.$$

What is the maximum efficiency (in %) at unity $$pf$$ load?

A
$$95.1$$
B
$$96.2$$
C
$$96.4$$
D
$$98.1$$
4
GATE EE 2006
MCQ (Single Correct Answer)
+2
-0.6
Two transformers are to be operated in parallel such that they share load in proportion to their $$kVA$$ ratings. The rating of the first transformer is $$500$$ $$kVA$$ and its $$pu$$ leakage impedance is $$0.05$$ $$pu.$$ If the rating of second transformer is $$250$$ $$kVA,$$ its $$pu$$ leakage impedance is
A
$$0.20$$
B
$$0.10$$
C
$$0.25$$
D
$$0.025$$
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