Hi Darren,
From: Darren Logan <[EMAIL PROTECTED]>
> On this subject, in instrumentation for example
> is it best to connect 0V to MAINS EARTH or not?
Do you want to be able to measure floating? If not,
I would connect it to EARTH if your equipment (not
the senso) has a metal body, and not if it has
an isolated platic body.
> If you have an instrument & sensor, where the
> sensor is on a long screened cable and has a
> metallic body - is it best to connect the screen
> to 0V at the instrument end AND the sensor body,
> or just the instrument end.
This is always a conflict. To suppress EMC (for example
for European CE approval) it is usuallly best to
connect it at both ends. But the disadvantage is that
you create a ground loop. There can be currents running
through the shield, and when you weld in a machine,
you can burn out the cable (I have seen that). And you
can even get rf into your equipment. But generally
connecting it at both ends makes things better.
> If connected at both ends, the sensor body may be
> mains earthed - what effect does this have on the screen?
None, but do you electrically connect the body of the
sensor to ground by mounting? In that case there
is a loop. Don't be too worried about loops though.
What to do also depends on how the electronics is build.
Does it use GND as reference, or is it balanced etc.
Regards,
Pieter Hoeben
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