regenerative energy dissipater

[bsharp]

I have a Mill that I retro fit with a PC control and Copley Accelus drives. I have had it up and running for a few months and have most of the bugs worked out. Now that I have gotten comfortable with running it I would like to increase the servo performance a little. Currently I can only safely run at slower rapids because of the regenerative energy pumping my Filter capacitor to high and tripping the built in protection of the drives. I was thinking of building something inexpensively. On the Accelus drives there are 5 volt digital outs that can be setup to trigger at a "warning" voltage. I was thinking of using that to trigger a resistor to drain the access voltage. I am sure some one has already come up with a similar solution for this and I am just looking for A prim example on how.

[Geof]

On commercial machines the voltage sensing circuit closes a relay putting a high wattage resistor acros the DC supply when the voltage goes above a limit. You should be able to rig the 5v to do that. On the machines I have the high wattage resistor is nothing more than a stove element; cheap, available in a variety of wattages and designed to get really hot if necessary.

[bsharp]

Thanks GEOF
I have three 1 OHM 50 WATT resistors and a pretty big 75 amp IGBT that I think I could couple to an opto. The Power supply runs at around 84 Volts 30 amps and the Drive limits at a little over 90 Volts. I guess I will have to play around with it a little on the bench and see what I can come up with.