Re: [CAD_CAM_EDM_DRO] Re: Gecko 160-180V servo drivers

Mariss Freimanis wrote:

> Hi,
>
> Carlos, I have to go with Jon here. Though you can dispense with the
> transformer and just full-wave rectify and filter 115AC to get
> 160VDC, it is not nearly as safe.
>
> The step and direction are opto-isolated but how well is the encoder
> isolated from its case? If the encoder supply draw is more than 50mA
> and you have to use a +5VDC supply, how well is it isolated? What if
> you want to use the encoder outputs for other purposes as well? If
> you needed to 'scope the drive, you wouldn't be able to. These are
> just some of the potential problems. I am sure there would be others
> as well.

The biggest one is what happens if the power cable to the motor gets
dragged into the sliding ways, and it cuts through the wire. If the
main power supply is isolated, it will still cause major problems,
and depending on the safety systems in the servo amp, it will do
anything from light a fault light to blow fuses and transistors.
But, if this is connected directly through a rectifier to the power
line,
it is practically guaranteed that the servo amp will be destroyed,
with traces blown off the board all over the place, exploded
transistors, etc. flying through the air, computer meltdown,
and possibly electric shock to the operator (even if the machine
frame is well grounded, you can still get a jolt when a heavy
fault occurs.)

These are the kind of things that I worry about.

Jon