We are shop testing a system that is being shipped to a location with 380V @50Hz. All of the motors are rated 190/380V (jumpered for high voltage), 50Hz, 2860rpm. In the shop we are supplying 380V to the motors but can't provide anything other than 60Hz. Didn't think it would make a big difference but all of the motors are drawing more than 4 x their FLA unloaded. This is happening on 3 different sized drives from 3 different manufacturers. Does 10Hz really make that much of a difference? It's not uncommon to over-freq a motor with a VFD without any problems but does that fact that the motors are directly connected to the lines make a difference?