A higher frequency motor will need either lower voltage or higher frequency otherwise it will overheat. If the 2kW motor is a 50Hz motor while the larger is 200kW it need a different V/F curve.
Nicklas Karlsson On Wed, 26 Nov 2014 22:51:59 +0200 Viesturs Lācis <viesturs.la...@gmail.com> wrote: > 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 ------------------------------------------------------------------------------ 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
