2014-11-26 22:30 GMT+02:00 andy pugh <bodge...@gmail.com>: > On 26 November 2014 at 18:50, Karlsson & Wang > <nicklas.karls...@karlssonwang.se> wrote: >> High voltage on low frequency will overheat an induction motor. > > I am pretty sure that Viesturs knows this. His question is why his VFD > won't go above 8Hz. >
Yes! Thanks, Andy! I just do not understand, why it does not work with those spindle motors (I am now trying to run one motor at a time), while the same motor works with a smaller, 2kW VFD. This 11 kW VFD works with "normal" 0,55 kW 4-pole motor (attached to gearbox), so I do not get this. I tend to agree with Jon about the low inductivity - low inductivity means high current and that is what heats the motor up - ok, I get that. But why does 2 kW VFD works with this motor, but 11 kW does not? Are those current sensing elements less sensitive that bigger VFD cannot measure changes of current in motor as needed? Then I guess that attaching 2 motors in parallel should improve it. Ron, of course, initial phase alignment of motors would not match. Until the voltage is applied to motor and all the phases are automagically aligned. I am certain that this is not a problem here. BTW it turns on and increases the frequency as expected, when no motor is attached at all. The frequency command is provided by potentiometer on front panel, I do not intend to use any kind of analog signals or communication bus for this purpose. Ok, I will just try to make some video with my phone tomorrow to show it. Viesturs ------------------------------------------------------------------------------ Download BIRT iHub F-Type - The Free Enterprise-Grade BIRT Server from Actuate! Instantly Supercharge Your Business Reports and Dashboards with Interactivity, Sharing, Native Excel Exports, App Integration & more Get technology previously reserved for billion-dollar corporations, FREE http://pubads.g.doubleclick.net/gampad/clk?id=157005751&iu=/4140/ostg.clktrk _______________________________________________ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
