1 What are the main differences between singleunit threephas

1. What are the main differences between single-unit, three-phase power transformers and three-phase transformer banks?

2. How is it possible to confirm that the wye-connected secondary windings of a three-phase transformer bank are properly connected (i.e., that winding polarity is respected)? Explain briefly.

3. How is it possible to confirm that the delta-connected secondary windings of a three-phase transformer bank are properly connected (i.e., that winding polarity is respected) before closing the delta? Explain briefly.

4. Consider a three-phase transformer bank connected in a delta-wye configuration. Each winding at the primary of the three-phase transformer bank is made of 800 turns of wire, while each winding at the secondary is made of 1340 turns of wire. Knowing that the line voltage EPri at the primary is equal to 208 V, determine the line voltage ESec at the secondary.

5. Consider a three-phase transformer bank connected in a wye-delta configuration. Each winding at the primary of the three-phase transformer bank is made of 4800 turns of wire, while each winding at the secondary is made of 1600 turns of wire. Knowing that the line voltage EPri at the primary is equal to 75 kV, determine the line voltage ESec at the secondary.

please I need the ansewrs in typing by a computernot hand written. Thanks

Solution

Construction wise single unit 3 phase transformer is only transformer with core having 3 primary and secondary windings wounded such that they are 120 degrees out of phase with one another

where as 3 transformer banks means ,3 separate single phase transformers interconnected externally as star/delta to make 3 phase transformer

Both has its own advantages and disadvantage,Single 3 phase transformer costs around 15 % less than bank of three single phase transformers and it occupies less space than 3 single phase transformers

advantage of using bank of three single phase transformers is that, if one unit of the bank becomes out of order, then the bank can be run as open delta.and the transportation is also easy as we can carry single phase transformers individually when it comes to larger ratings

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