Re: Power Supply Circuit

Tony,

Yes, I have taken that into consideration. The circuit trips 15
milliseconds after the absense of a charge current pulse. Be it 50 or
60 Hz, it will trip after a single missed pulse (8.33 or 10 mS).

The G298 is finished and is ready for prototype boards. Next week our
totally revamped website launches and the G298 is pictured there.

Mariss

--- In CAD_CAM_EDM_DRO@y..., Tony Jeffree <tony@j...> wrote:
> Mariss -
>
> Sounds excellent.
>
> Presumably this circuit will work equally well with the 50Hz mains
> frequency this side o' the pond?
>
> Regards,
> Tony
>
> P.S. While I remember it - what progress with the G297 (or was it
G298)?
>
>
> At 03:50 15/06/2002 +0000, you wrote:
> >What it does is sense the 120Hz cap charge restoring current
pulses.
> >If these are absent, such as when the AC power is shut off or if
the
> >cap is being backdriven by a drive, a power MOSFET crowbars a wire-
> >wound power resistor across the supply. The resistor is sized so
that
> >it draws the full current rating of the supply thru it.
> >
> >A 10A, 80VDC supply filter cap would be 10,000uF for a 10% ripple
at
> >max current. The crowbar resistor would be 8 Ohms, forming a time
> >constant of 80 milli-seconds. Three time constants would be about a
> >1/4 second discharge time for the supply after AC power shut-off.
> >
> >A backdriven supply develops a voltage rise on its filter cap. This
> >biases the bridge rectifier off and no current flows thru it. The
> >sense circuit again places an 8 Ohm load across the supply until
> >rectifier current is re-established.