1
GATE EE 2008
MCQ (Single Correct Answer)
+2
-0.6
Three single-phase transformers are connected to form a $$3$$-phase transformer bank. The transformers are connected in the following manner. GATE EE 2008 Electrical Machines - Transformers Question 20 English

The transformer connection will be represented by

A
$$Yd0$$
B
$$Yd1$$
C
$$Yd6$$
D
$$Yd11$$
2
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
3
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
$$99.241\% $$
4
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
$$98.1$$
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