Re: Rutex

--- In CAD_CAM_EDM_DRO@yahoogroups.com, Jon Elson <elson@...> wrote:

>
> vrsculptor wrote:
> > Has Rutex come back to life? I received a note from Vladimir and their
> > web pages hows inventory available on all the 2000 series drives. Are
> > these drives the classic version or a new revision?
> Umm, yes, apparently. But, you might want to get an independant
> opinion of any of their hardware before you go and spend money
> there. I don't know how much improvement they have made on
> their old products, or whether they have even gotten their
> wildly inflated specs back in line. They at one time had taken
> the published International Rectifier 25 C - infinite heat sink
> - one-time survival spec and made it the peak current rating of
> their drive at 75 C. That was something like 220 A. Of course,
> their connectors were rated at 20 A at best, and that would have
> dissipated 2420 W in their current sense resistors, even if the
> transistors could have survived such an assault! Oh, I just
> looked, they STILL list the R2020 at 220 A peak, and 0-70 C
> temperature. Sorry to be blunt, but WHAT a crock! The 2-piece
> plug connectors on the R2030 are rated at either 15.6 or 20 A
> depending on which manufacturer's parts he uses. That amp is
> rated to 110 A. The connector would explode in a bright flash
> at 110 A. (Oh, I see up on the first page it says 34 A for the
> R2010/R2030, and 56 A for the R2020. So, why the insane numbers
> in the Electrical Specifications below?)
>
> Ask Vladimir if he's ever TESTED the complete R2020 amp to 220
> A! (I know the answer to this, he lets his CUSTOMERS do his
> testing....)
>
> And, of course, you need these hideous series resistors between
> the motor and amp to cover up the other bad design features.
> That's not on the data sheet, but with larger motors, the
> returned current when braking will pop transistors unless you
> add these resistors, which horribly sap system performance.
> As far as I know, you still need these.
>
> Jon
>

I have read the Rutex specification sheets and notes very carefully and find that there is nothing wrong with their specifications. Current ratings vary with model number and are broken down by maximum average current, maximum peak motor current and then also the maximum peak motor current which is the high figure mentioned for a time of less than one millisecond. They also accurately give the current ratings for the devices used in their output bridge as either 34 amp devices or 56 amp devices. For example and in the same order for the R2010 model the current ratings are 10, 20 and 110 Amps. Remember the 110 Amp rating is for <1ms. Some manufactures don't even give you this detail.
As far as the resistors in series with the motor their use is fully explained in the application note and are only suggested to be used when motor resistance, power supply voltage and drive current cannot be matched up properly due to poor selection of motor and power supply voltage.

I own opinion of the Rutex drives is quite high and have a very nice setup with uses SPI communications for setting up the servo gains and response times.