We propose to install two 12-pulse, AC VFD drives for two 690V, 3Ph AC motors of rating 500KW each. (Total load = 1,000KW). Both the VFDs are fed by a common 3 winding phase shifting transformer. The harmonics generation may be less because of 12 pulse configuration.
However, what is the margin to be given on the capacity of the transformer in order to offset the adverse effect of the harmonics?