Electrical Machine - IES Academy
Electrical Machine - IES Academy
Electrical Machine - IES Academy
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India’s No. 1<br />
<strong>IES</strong> <strong>Academy</strong><br />
Transformer<br />
Chapter-1<br />
<strong>IES</strong>-44. Ans. (a)<br />
<strong>IES</strong>-45. Ans. (a)<br />
<strong>IES</strong>-46. Ans. (c)<br />
<strong>IES</strong>-47. Ans. (c) Grains are oriented to increase μ . r<br />
<strong>IES</strong>-48. Ans. (b)<br />
<strong>IES</strong>-49. Ans. (b)<br />
<strong>IES</strong>-50. Ans. (b) Percentage voltage regulation for lagging p.f. = ( ∈ θ ∈ θ )<br />
r<br />
COS + sin × 100<br />
as ∈r = 0.01 & ∈<br />
x<br />
= 0.04<br />
∴ % VR = (0.01 × 0.8 + 0.04 × 0.6) × 100 = 3.2%<br />
∴ % VR for leading p. f. = (0.01 × 0.8 – 0.04 × 0.6) × 100 = –1.6%<br />
<strong>IES</strong>-51. Ans. (a) For lagging load ‘% R’ = 1 (2 × 0.8 + 4 × 0.6) = 4%<br />
For leading load ‘% R' = 1(2 × 0.8 – 4 × 0.6) = – 0.8%.<br />
<strong>IES</strong>-52. Ans. (c)<br />
<strong>IES</strong>-53. Ans. (d) Regulation of ideal transfer is 0% hence assertion is not correct.<br />
<strong>IES</strong>-54. Ans. (a)<br />
<strong>IES</strong>-55. Ans. (b) In approximate equivalent circuit, the parallel magnetising branch is shifted<br />
to the left of the primary leakage impedance with the assumption that voltage<br />
drop in the primary impedance due to the exciting current can be neglected.<br />
<strong>IES</strong>-56. Ans. (b) Short circuit test is performed to find copper losses not core losses.<br />
<strong>IES</strong>-57. Ans. (d) Dust & Moisture is already taken care by Silica Jel. Due to heating oxidation<br />
of transformer oil is there.<br />
<strong>IES</strong>-58. Ans. (a)<br />
x<br />
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