Sizing of Rectifier Transformer For 4 Numbers of DC Motor

Hi Cokoh2 : So each 600Vac transfo secondary feeds 2 drives and there are two secondaries , correct ? Q1 : what is the input power to each 600Vac drive that has a load of 600kw dc motor ? ( you must convert the output power of 600kw dc to input power ac at the drive input! this will include all losses/efficiencies/power factors/etc of the drive and its load, so that you can see what the transfo secondary sees as a load.) You mentioned 1224 amp ac @ 600Vac for the drive input; is this the rating of the drive or the input power draw of the load, which would be the answer to my question ? ( this equates to 1271 kva and if it is the input power draw , it would indicate a very inefficient drive? ).

Hi Cokoh2

Be careful! get the transformer manufacturer to calculate the unit for you as the load looks like it will have a very high harmonic content. Specifying this using only power figures may result in overheating. The trafo core may well become magnetically saturated at the pulse peaks.

Even if you have to pay for their engineer to do the calculations for you it would be worth while as this transformer will cost in the order of $US 20,000 (€14,000) and to get it wrong would be very costly! (i've assumed 600V /1224A as the total output thus giving 734,400 kVA (0.75 MVA)