216. Three single phase transformer each wit h a 10 kVA rating are connected in a closed delta arrangement. If one transformer is taken out, the output capacity of the system will be

1. 1. 20 kVA

   
   
   

   2. 8.66 kVA

   
   
   

   3. 17.39 kVA

   
   
   

   4. 10 kVA

   
   
   

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   NA

   Correct Option: C

   NA

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217. A 50 Hz transformer having equal hysteresis and eddy current losses at rated excitation is operated at 45 Hz at 90% of its rated voltage compared to rated operating point, the core losses under this condition will be

1. 1. reduce by 10%

   
   
   

   2. reduce by 19%

   
   
   

   3. reduce by 14.5%

   
   
   

   4. remain unchanged

   
   
   

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   NA

   Correct Option: C

   NA

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218. In a 4: 1 turn ratio transformer, the leakage reactance as referred to the secondary side is 0.05 pu. The leakage reactance as referred to primary is

1. 1. 0.05 ohm

   
   
   

   2. 0.05 pu

   
   
   

   3. 0.8 pu

   
   
   

   4. 0.2 pu

   
   
   

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   NA

   Correct Option: B

   NA

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219. A transformer has a voltage regulation of 3% at full load, 0.8 power factor lagging. At full load unit power factor, the regulation will be

1. 1. 3%

   
   
   

   2. negative

   
   
   

   3. less than 3%

   
   
   

   4. more than 3%

   
   
   

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   NA

   Correct Option: B

   NA

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220. The magnetizing current in a transformer is rich in

1. 1. 3rd harmonics

   
   
   

   2. 5th harmonics

   
   
   

   3. 7th harmonics

   
   
   

   4. 13th harmonics

   
   
   

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   NA

   Correct Option: A

   NA

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