andy pugh wrote: > I think we are discussing different things. > > I am saying that if a motor takes 200A per phase on 3 wires out of the > VFD and that power comes into the VFD on 2 wires, then the current in > the 2 wires will be more than 200A each. > OK, that is a whole different thing. Induction motors draw huge inductive currents, worse when idling, better when at full load, but still a lot.
So motor amps time motor volts does NOT equal Watts drawn from the mains. The VFD recirculates this reactive current, and draws a much better power factor from the mains. So, in fact, motors running at light load will draw MUCH less current from the mains when run via a VFD! This is a significant reason industrial users use VFDs, it keeps them from getting in trouble with the utility, or having to install a huge phase correction bank with automatic controls. At full load, then what you say will be true. Jon ------------------------------------------------------------------------------ Colocation vs. Managed Hosting A question and answer guide to determining the best fit for your organization - today and in the future. http://p.sf.net/sfu/internap-sfd2d _______________________________________________ Emc-users mailing list [email protected] https://lists.sourceforge.net/lists/listinfo/emc-users
