On Thursday 21 May 2020 01:57:06 andrew beck wrote:

> hey peter
>
> I had a look and the unless there is a shorted out pin in the servo
> drive connector itself I think the wiring is all good.
>
> and I highly doubt the servo drive has problems all I did was connect
> the 24v back into the servo on pin which is how it has been running
> for the last ages.
>
> anyway how do you recommend commoning the grounds?
>
> it is as simple as connecting the field power 0v ground with a wire to
> the logic power 0v ground?
>
Yes, but how you do it can be very important.

In your control box, install a longer bolt, #6 or #8-32 to the chassis. 
4mm if metric.

Connect all grounds to this bolt, checking that they are not grounded at 
the far end.  By doing this, you are establishing a single point ground 
that is the zero volt reference for the whole system. Connect this bolt 
to the building static ground, the bare wire in most power cabling.

Connect the machines frame to this bolt.

Connect the - rails of all supplies to this bolt.

Connect the - terminals of all cards to this bolt.

Break the 3rd pin off the computers supply cable and connect the 
computers chassis to this bolt. Power the computer not from the wall, 
but from the same power feeding this box. 

Connect the shielding of all shielded cabling to this bolt. Do not 
connect the far end of this shielding to anything that is otherwise 
grounded.

By making sure these grounds are not connected anyplace else you are 
breaking any ground loops which can and will act as antennas to insert 
noise into your control signals.

By having this single point ground, a nearby lightning strike can inject 
a 100k volt pulse into the system ground as what would be called 
a "ground bounce",  but the system will not see it as noise nor be 
damaged, because everything is bouncing in unison.

Regardless of what that bolt does during the strike, the 5 volt supply 
remains at 5 volts to this bolt, and the 24 volt supply remains at 24 
volts to this bolt. 

And when the storm is done, your chances of having anything damaged is 
reduced to the vanishing point.

Stay well Andrew.

[...]

Cheers, Gene Heskett
-- 
"There are four boxes to be used in defense of liberty:
 soap, ballot, jury, and ammo. Please use in that order."
-Ed Howdershelt (Author)
If we desire respect for the law, we must first make the law respectable.
 - Louis D. Brandeis
Genes Web page <http://geneslinuxbox.net:6309/gene>


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