Re: Gecko320 on 88 VDC and 15 amps

--- In CAD_CAM_EDM_DRO@yahoogroups.com, "Dan Mauch" <dmauch@s...>
wrote:

> As I recall the G320 and the Rutex 100V20A servo amps both use the

IRF540

> fets. The only difference is the conservative rating that

Geckodrives places

> on the G320/G340's
> Dan

If I can read between the lines.......

Mariss has completed the Vampire dirve and is gearing up for
production.... means he recognizes how dumb we are with making
mistakes in installing. ie: enough failures to warrent attention.

There is an energy dump circuit. It is quite possible Rutex offers
that in the drive ? I would kinda expect that the G3x line may get a
Vampire mod in the future ?

Mariss had mentioned that the normal failures under 80 volts is
almost insignifigant.

and that failures above 100 volts is excessive.

and that returned energy can spike by 20% or so (kinda fuzzy on the
numbers as I read the test results so long ago) But, it was scarry
to think that running a drive near rating would kill it.

Witness the Xylotex boards. the chip is rated for 35 volts. and
fails at 36 volts. instead of shooting for an energy dump, they
derated the power suply to 24 volts to reduce the problem.

I think those drivers when used at 32 volts (24xfmr) were falling
like flies.

So, knowing there is a back emf, and knowing how high it will spike,
you can predict what voltage your drives will see. Enter the energy
dump circuits.

As I noted in another post, there are more than enough power supply
options to get the proper voltage, there are enough motor options as
well.

In my case, I think I need about 300 watts for the plasma table. so,
I'm designing around a 1-1/2 hp 110 V motor. that will offer much
closer to 1,000 watts, so if I just lose the whole upper half (
speed, votage amps), I still have more power than I require.

Dave