Galvanic Isolation For Transmitters

Most commonly by means of a transformer or opto-isolator.

http://lmgtfy.com/?q=galvanic+isolation

You're welcome.

And it even types in the search terms for you. Brilliant!

I'd use a galvanic isolator, then, I'm funny that way.

You have to choose the good material for galvanic to provided the transmitter.

Please do tell precisely what is needing the galvanic isolation from the transmitter? Are you worried about neutral currents from the transmitter? Let us re-define transmitter for a minute, as a generic readout device, interfaced with sensor/amplifier and with the DCS (PLC-HMI combination usually).

If the transmitter has digital communication with the DCS, then this usually has a high degree of common-mode signal/noise ratio, and is not permitted to "ground fault", and usually the cable will include a shielding ground to avoid interferences. If the sensor is an old-style analog sensor, then the signal is usually sent over a shielded bundle that includes the actual signal, and perhaps a temperature sensor, so probably a minimum of five wires, with one as shield/ground.

If the system is set up incorrectly as to "Mecca" ground, there can be a ground loop, and if there is a significant potential on this, an injected corrosion potential on conduits and pipes carrying aqueous fluids will result. Avoid ground loops. Make sure that all the equipment is properly grounded through out the plant environment. If there is cathodic protection circuit on major piping, make sure this is installed correctly so that a protected line does not cross path of unprotected line underground. So forth and so on. In such a case as previously mentioned, the one pipe will corrode out and fail quite unexpectedly and in some cases far more rapidly than projected.

If the sensor is a pH or conductivity sensor, these are supplied with a high impedances that are usually sufficient to be considered isolated with respect to the induction of corrosion on nearby metal piping.

Thanks James.. What i had a query that is there any feasibility provided at transmitter side for Galvanic isolation till now what we provided was isolation optical or galvanic on PLC or DCS end.
if it is possible is there need of any extra accessory required for the isolation for transmitter.

The only requirement I can possibly foresee is the need to de-couple any direct insertion probes from the metals involved in process vessel/piping. This apparently means that the metal should be well grounded in accordance with issued standards, and the transmitter/probe do not introduce any stray potential on that metal.

How about a good answer (if you thought the previous was a GA)?