221. A 2-phase, 4-pole permanent magnet stepper motor has a step of

1. 1. 90°

   
   
   

   2. 45°

   
   
   

   3. 30°

   
   
   

   4. 22½°

   
   
   

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1. View Hint View Answer Discuss in Forum

   NA

   Correct Option: D

   NA

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222. A 400/200 V transformer has a PU impedance of 0.05. The HV side voltage required to circulate full load current during short circuit test is

1. 1. 40 V

   
   
   

   2. 20 V

   
   
   

   3. 10 V

   
   
   

   4. 5 V

   
   
   

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1. View Hint View Answer Discuss in Forum

   NA

   Correct Option: B

   NA

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223. A 200/100 V 50 Hz transformer is to be excited at 40 Hz from the 100 V side. For the exciting current to remain the same, the applied voltage should be

1. 1. 150 V

   
   
   

   2. 125 V

   
   
   

   3. 100 V

   
   
   

   4. 80 V

   
   
   

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1. View Hint View Answer Discuss in Forum

   NA

   Correct Option: D

   NA

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224. A 200/100 V 50 Hz transformer is to be excited at 40 Hz from the 100 V side. For the exciting current to remain the same, the applied voltage should be

1. 1. 150 V

   
   
   

   2. 125 V

   
   
   

   3. 100 V

   
   
   

   4. 80 V

   
   
   

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1. View Hint View Answer Discuss in Forum

   NA

   Correct Option: D

   NA

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225. When short -circuit test on a transformer is performed at 25V, 50 Hz, the drawn current I₁ is at a lagging p.f. angle of φ₁. If test is performed at 25 V, 25 Hz and drawn current I₂ is at a lagging p.f. angle of φ₂, then

1. 1. I₂ > I₁ and φ₂ < φ₁

   
   
   

   2. I₂ < I₁ and φ₂ < φ₁

   
   
   

   3. I₂ > I₁ and φ₂ > φ₁

   
   
   

   4. I₂ < I₁ and φ₂ > φ₁

   
   
   

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1. View Hint View Answer Discuss in Forum

   NA

   Correct Option: C

   NA

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