Loop Powered 24VDC 4-20mA signal

If you're running a dirty switching regulator you may inject noise into the signal (depending on the design of the transmitter and the PLC input filter).

Be sure to check for any grounding issues.

Other than that it should work.

Best regards, Spehro Pefhany

Hi

I agree with Spehro.

Regards,

U.

"Poor is the pupil who does not surpass his master"

-- Leonardo.

"Spehro Pefhany" (e)k berri-mezuan idatzi du: snipped-for-privacy@4ax.com...

Thanks Spehro

By grounding issues do you mean if the 4-20mA signal is powered by a floating supply?

cheers

Ethean

Basically we do not mix 4-20 mA signals with other signals or electrical components in the plant.

The reason is simple, you may introduce noise in the 4-20mA and this will cause problems in your process control

The supply and everything connected to it-- should have at most one ground (including sneak paths through non-isolated transmitters and grounded sensors).

Best regards, Spehro Pefhany

He didn't ask about mixing signals. He asked about sharing a power supply. If ground considerations permit it, good bypassing should make it feasible. It's an amateur (or emergency) thing to do. The cost of an extra supply is far less than the cost of an hour's down time.

Jerry

Sorry I did not mean to mix signals, anyway just to make myself clear. In our projects we provide two different power supplies: one for digital points, one for analog points. Therefore we do not have one single power supply to everything.

I agree with you when you say " The cost of an extra supply is far less than the cost of an hour's down time. "

Fl=E1vio

Thanks guys