Re: Power Supply

Hello,

Didn't see this mentioned yet...

WHY are you running 6.1 amp motors at 7 amps??? Do yourself and the
motors a favor and get the resistors in the geckos to limit the
current to the rated value. Unless you feel your motor design skills
exceed those of the mfr... (Would you exceed redline of your
automobile engine "for months"???)

The side benefits will include longer motor life, cooler operation,
and smoother motor rotation. Excess amps might help an ego, but not a
motor.

Next, motors are BOTH motor and generator anytime they are turning...

Factor in what the turning motor is adding to the supply for
the "other" motors to use and you might have another part of your
answer

Hope this helps,

Ballendo

--- In CAD_CAM_EDM_DRO@yahoogroups.com, Ron K <godsone@e...> wrote:
>
>
> caudlet wrote:
>
> > SNIP
> >
> >>In reality the 5amp fuse was a mistake I thought I had put in a
> >>
> >>
> >10amp but the system has been running like this for several
months .
> >
> >
> >>--
> >>Ron Kline
> >>
> >>American Precision Ceramics
> >>
> >>
> >
> >Ron what you are seeing is reality vs theory. There are a lot of
> >factors that may be at work here. The motors Average current
which
> >is the Gecko 7 A limit times the duty factor is evidently a lot
less
> >than the nameplate rating. If a motor only needs 20% of the pulse
> >width to move the load then the AVERAGE current over time is only
> >20%. Since things like transformers and fuses can withstand short
> >periods of 100% overloads the 5A fuse could easily handle 10A at
50%
> >duty cycle.
> >
> >The only real way to test is put a DC ammeter in the DC line in
> >series with the load and do some measurements. A current probe on
a
> >scope would give you the real picture from a dynamic perspective.
You
> >might be surprised to see how much less the current draw is on
> >average than you would calculate from the motor specs.
> >
> >If you run mostly two axis moves then two motors would probably
only
> >draw 8 to 10 amps worst case. Sounds like you are not running the
> >motors anywhere near their max limits.
> >
> >Another good indicator is that things are probably not running
hot:
> >motors, power supply, etc are warm but not too hot to leave you
hand
> >on I would guess.
> >
> >Take it as good news and don't worry about it too much. The only
> >true way to design a power supply is to have the actual load in
the
> >actual conditions it runs in to measure then do the calculations.
> >Taking numbers off components and adding them all up will only get
> >you in the ballpark parking lot. We all tend to overdesign the
power
> >supply because of the fear of putting a lot of time and effort
into
> >something that ends up being too small and to combat Murphy's Law.
> >
> >The good news is that your power supply will last a long time.
> >
> >
> >
> Now that is an explination I can understand
>
> Thanks
>
> --
> Ron Kline
>
> American Precision Ceramics
>
>
>
> [Non-text portions of this message have been removed]