When is opto-isolation necessary?
When is opto-isolation necessary?
(OP)
On a proposed project I have multiple 4-20 mA process control signals interfacing to an AB PLC system via remote I/O. There are two options to choose from in the remote I/O, isolated and non-isolated. There is a big price difference between the options. I normally think of optical isolation for voltage spikes, ie. lightning strikes, will I gain possible noise suppression?





RE: When is opto-isolation necessary?
RE: When is opto-isolation necessary?
RE: When is opto-isolation necessary?
http://www.sensormag.com/articles/0400/70/main.html
http://www.sensormag.com/articles/0199/iso0199/main.html
RE: When is opto-isolation necessary?
Jp
RE: When is opto-isolation necessary?
Another common issue where 4-20 ma loops is concerned is the type of transmitter in use. If the loop is powered by the control system no isolation is required.
If the transmitter is 4-wire (field powered) then isolation is required to prevent tying the field power to the control system power. At a minimum the signal will drift and be inacurate. At worst a fault could bring the system down.
RE: When is opto-isolation necessary?