Power Transformer Question

i don't think I have the full question.

The generator itself is star wound which then feeds the station distribution transformer which will normally steps the voltage up to a higher level. The load side winding of this transformer is in Delta so as to distribute the maximum power at its highest voltage. High voltage means smaller overhead line conductors and less line losses. Transmitting at low voltages and high currents results in higher line losses and severe voltage drop.

The final distributing transformers have Delta primary sides to take the high voltage power and transfer it to a safe usable voltage - in Europe this is 400/230V. The secondary low voltage winding is in star in order to provide the mid point of the three - 3 phase windings, This mid point is essentially one end of each of the three secondary windings provide the neutral point which is required for 400v 3 phase and neutral and 230v single phase and neutral distribution.

Obviously the USA and Canada have a further transformer step to provide the 110v distribution.

USA and CANADA and those countries on 110 volts ac are probably from local transformers stepping down to 100 volts in one go.

This would be more efficient in terms of reduced heat loss.

Transformers are the most efficient item mankind has invented, resulting in very little energy loss.

So

energy-in = energy-out + ( some heat energy of a few percent )

Regards,

Dr M.

Delta connection helps in the elimination of ZERO SEQUENCE COMPONENT.

Delta wye connection will certainly prevent transfering of zero sequence from the delta to the wye side.

This is easely understood, if you draw the zero sequence model for a delta wye transformer.

The main aim to use delta is to reduce the cost for laying the transmission lines cost will become more if more conductors are added.

normally the electrical conductors cost used for HVAC is very high and its of several thousand kilometers

Total cost = (cost of conductor + laying cost + other supporting equipments) * Kilometer.

so because of this reason we go for 3 wire transmission from power generation station to sub stations.

generally power transformers are connected in star / delta connection to supprese the third hormonics. in generating transformer the generator side is a low voltage side. higher voltage side we can not make delta due to requirement of higher insulation. hence generally higher voltage side are connected in star side. Since in gen. tr. generator side low voltage tr. is in delta connected.