1
GATE EE 2018
MCQ (Single Correct Answer)
+2
-0.6
A transformer with toroidal core of permeability $$\mu $$ is shown in the figure. Assuming uniform flux density across the circular core cross-section of radius r $$ \ll $$ R, and neglecting any leakage flux, the best estimate for the mean radius R is GATE EE 2018 Electrical Machines - Transformers Question 6 English
A
$${{\mu V{r^2}N_P^2\omega } \over I}$$
B
$${{\mu I{r^2}{N_P}{N_S}\omega } \over V}$$
C
$${{\mu V{r^2}N_P^2\omega } \over {2I}}$$
D
$${{\mu V{r^2}N_P^2\omega } \over {2V}}$$
2
GATE EE 2018
MCQ (Single Correct Answer)
+1
-0.3
A single-phase 100 kVA, 1000 V / 100 V, 50 Hz transformer has a voltage drop of 5% across its series impedance at full load. Of this, 3% is due to resistance. The percentage regulation of the transformer at full load with 0.8 lagging power factor is
A
4.8
B
6.8
C
8.8
D
10.8
3
GATE EE 2018
Numerical
+1
-0
A separately excited dc motor has an armature resistance R$$a$$ = 0.05⁡Ω. The field excitation is kept constant. At an armature voltage of 100 V, the motor produces a torque of 500 Nm at zero speed. Neglecting all mechanical losses, the no-load speed of the motor (in radian/s) for an armature voltage of 150 V is _____ (up to 2 decimal places).
Your input ____
4
GATE EE 2018
Numerical
+2
-0
A 3-phase 900 kVA, 3 kV / $$\sqrt 3 $$ kV (Δ/Y), 50 Hz transformer has primary (high voltage side) resistance per phase of 0.3 Ω and secondary (low voltage side) resistance per phase of 0.02 Ω. Iron loss of the transformer is 10 kW. The full load % efficiency of the transformer operated at unity power factor is _______ (up to 2 decimal places).
Your input ____
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