I have a few I/p transducers(which work on 4-20mA loop current) and I have made a single cable for all of them, they each have posititive, negative and Ground wires. The controller I have for these I/P transducers have only positive and negative wires. I have a few questions and would really appreciate some advise

1) What should I do with the ground wires?

2) The controller sits in a huge metal cabinet, should I connect the ground wires to the cabinet?

3) What kind of grounding should be done, is it signal grounding, chasis grounding or earthing? I'm confused about this. The symbol I saw on the I/P transducer is the earthing symbol but since this is a current loop I though it would be a signal ground.

Details about the parts:

I/P transducer used: https://www.omega.com/en-us/control-and-monitoring-devices/controllers/pressure-converters/p/IP710

V/I converter that is connected to the transducer: https://www.amazon.com/KNACRO-Voltage-Current-Conversion-current/dp/B0793MLDXZ/ref=pd_cp_421_1?pd_rd_w=61AJ1&pf_rd_p=ef4dc990-a9ca-4945-ae0b-f8d549198ed6&pf_rd_r=PAN3QRZF0ENADYC2DJ7N&pd_rd_r=4b180e82-a70a-11e9-8b3f-05565185fef1&pd_rd_wg=740lv&pd_rd_i=B0793LQZWC&refRID=PAN3QRZF0ENADYC2DJ7N&th=1

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    \$\begingroup\$ As usual, there is no datasheet available from Amazon. "No datasheet? No sale!" \$\endgroup\$ – Transistor Aug 7 '19 at 21:39

Based on the transducer manual, you should just connect it to case (earth) ground. It's probably just for shielding.

screenshot from manual

As for the voltage to current signal converter. I don't see any reason it would need an earth connection. Your power supply negative should be tied to earth somewhere anyway.

One last thing, with a component this expensive it's reasonable for you to call up omega and double check this with them. The support is part of what you're paying for.

  • \$\begingroup\$ Thanks a lot for the answer, so I'm planning to pigtail all the groundwires and connect them to the metal cabinet. Would that work? \$\endgroup\$ – Veda Aug 13 '19 at 6:45

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