Basic_Electrical_Engineering_4th_edition
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ELECTRICAL ENGINEERING |
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Example 5.15. A 1 150012300 V transformer is rated at 100 KVA as a 2-winding trans |
former. If the two windings are connected in series to form an auto transformer. What will be the voltage ratio and output ?
Solution. We will consider only addition polarities of the two windings as the primary and the secondary will he either 11.5 KV winding or 2.3 KV winding.
The two possible connections are :
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1 3.8 kV |
1 1 .5 kV |
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1 3.8 kV |
2.3 kV |
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2.3 kV |
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(a) |
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(b) |
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Fig. ES.15 |
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(a) The transformation ratio is |
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§5_ = 1.2 = n |
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using equation (5.39) |
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13.8115 = |
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1 |
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P. |
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_p_ i _ l=6- n |
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where |
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100 KVA |
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pn = |
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5 |
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-1: |
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Substituting |
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100 = 1 - |
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Therefore,I, |
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6 |
6 |
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or |
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P = 600 KVA |
600 KVA Ans. |
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the rating of auto |
transformer is |
13.8/11.5 KV, |
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p |
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(b)The transformation ratio is
13.8= 6
2.3
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__i_ |
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1 |
Again using equation (5.39) |
= l - |
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p,p |
n |
