If I use a Y source and 3 lamps. One time I connect the load in delta, the other time in wye. I measure the power and the power in the load in delta is three times bigger than the power from wye. How come?
Anyone have a link where they explain this or even more differences between delta and wye?

 

Perhaps this will help clear things up: http://www.allaboutcircuits.com/vol_2/chpt_10/5.html

 

When you connect the loads in "Star" format Y, the voltage is approx 230 Volts across the load because of the neutral, but when connected in "Delta" the supply voltage is appx 415 Volts across the load because there is no neutral but "Two phases"..

 

If I use a Y source and 3 lamps. One time I connect the load in delta, the other time in wye. I measure the power and the power in the load in delta is three times bigger than the power from wye. How come?
Anyone have a link where they explain this or even more differences between delta and wye?

The reason why the load side (delta) is three times bigger than the power from the wye, because of the transformer turn ratio ( the square root of 3) and also the phase differences. One side usually lead by 30 degree out of phase from the other side according to there design.

 

http://forum.allaboutcircuits.com/showthread.php?t=24921