Re: [CAD_CAM_EDM_DRO] Re: Power Supply and Capacitor Questions Help!!

Hi Bernard,
Thank you for taking the time to respond. I did what you suggested and put the 33 v tap and the 12v together in parallel and it works. I misread those the other day. Anyways I'm getting about 47 volts out of my supply. Jon Elson mentioned on another email that these two sets of taps may not be isolated from one another. Its working so I'm assuming they are. I left my Transformer plugged in for about 2 hours with no load and one lead from each set still connected and it got rather warm, still touchable but warm. is this normal? Also, do I need all these Capacitors?(they consume 1/4th of my cabinet) Ive got 3 at 100 vdc and 15,000 macrafarads each. On another Email someone mentioned that two at this value should be sufficient. And the bleed resistors are getting omitted due to the responses ive recieved. Everyone is saying I dont need them because Gecko has them built in.


Ron
Bernard R <bwjarandall@...> wrote:
--- In CAD_CAM_EDM_DRO@yahoogroups.com, "rogersmach"

Wire the capacitors in parallel, you only need 1 resistor if you feel
you need a bleed. Check the wire size of the transformer
secondaries, if they are similar, wire the 31 V in series with the 10
V, check with a voltmeter you should get 41 VAC, if its 21V swap one
pair of windings. Use one bridge rectifier across the 41VAC, when
connected with the capacitors you will get (41 x 1.414) - approx 1.5
(bridge diode drop) VDC, near enough 55 VDC, you can increase it to
slightly over 60VDC by also including the 4 volt tap, again if it is
of similar gage ( or bigger) than the other two. The 320s are
conservatively rated at 80VDC.

Bernard

> Hello,
>

I'm using a

> power supply from the old control of my bridgeport which has 4 set

of

> output taps on the secondary and their voltage values are: 1 set at
> 31 volts AC, 1 set at 10 volts AC, 1 set at 4 volts AC and the

other

> set read 0. In talking with Mariss at Gecko drive (brilliant man,
> hate to bother him), he suggested that I use about 60 volts DC with
> his drives. Which would reduce the speed with little effect on the
> torque (if I understood him correctly). And I would need a 100 volt
> DC capacitor rated at 45,000 macrofarad or greater. I could not
> locate a cap with this value and had to settle for 3 100 volt
> computer grade DC caps at 15,000 macrofarad. Question: Can I wire
> these 3 capacitors in series to achieve the same Macrofarad value?

I

> intend on using a 1.2k 5 watt bleed resistor on each. Next

Question:

> Would it be possible for me to run the 31 volt taps through one
> bridge rectifier and 10 volts through another bridge rectifier,

wire

> them in parallel to get my output up to around 41 volts DC? Is it
> possible to change the configuration of the primary side and get
> higher values? I intend to use the present supply temporarliy to

get

> operational, then acquire a more adequate supply later. At the 31
> volts it appears to be pushing the X axis (servo running directly

off

> of bridge at 31 volts DC without capacitor and a 2.5:1 reduction)
> about 30 inches/min Id like to get it around 70 or 80 inches /min
> rapid. Any more than that is unsafe on a bridgeport. Any input on

my

> inquiries would be appreciated.

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