Electrical and Electronics Engineering
Electrical Machines II
Assignment 2: Three Phase Transformers
- Explain in brief about the construction of three phase transformer.
- Draw all the vector group of transformer connection.
- Discuss in brief about the application of the four basic types of connections of three phase transformer.
- Discuss about the open delta connection and derive that the power transfer capacity is reduced by two third.
- Explain about the scott connection. How three phase to two phase transformation is done?
- Explain the parallel operation of the three phase transformers.
- Discuss the harmonic phenomenon for three phase transformer.
Three 1100/110 V transformers connected in delta-delta supply a lighting load of 100kW. If one of the transformer is out of service, determine the following:
- Current of each transformer in healthy condition.
- Current of each transformer when one transformer is out of order.
- kVA rating of each transformer if it supplies full load in open delta connection.
A 400 kVA load at 0.7 power factor lagging is supplied by three single phase transformers connected in ∆-∆ each. Each transformer is rated at 200 kVA, 2300/230 V. If one defective transformer is removed from service, calculate for the V-V connection,
- kVA load carried by each transformer.
- Percent rated load carried by each transformer.
- Total kVA ratings of transformer bank in V-V.
- Ratio of V-V bank to ∆-∆ bank transformer ratings.
- Percent increase in load on each transformer when one transformer is removed.