Convert a 0-200 Microamp Signal for use in PLC?
Convert a 0-200 Microamp Signal for use in PLC?
(OP)
I have an old turbine control system that uses black boxes for temperature and speed control. I'm trying to get the speed (passive Mag pick-up) and temperature signals (Type K Thermocouple) in to a PLC for monitoring. I think piggy backing off the Mag pick and taking the signal into a high speed counter card at the PLC should be straightforward.
The temperature signal is more complicated. There's only one Type K signal (wire) going straight to the black box. I'd rather not molest/piggyback the thermocouple signal (splitter has delays, drift, etc) so am looking at a 0-200 MICROamp output signal that is available off of the temp control black box (proportional to the input t/c signal) that I could use for monitoring. How in the world can I convert or get a 0-200 microamp signal in to a PLC?
The temperature signal is more complicated. There's only one Type K signal (wire) going straight to the black box. I'd rather not molest/piggyback the thermocouple signal (splitter has delays, drift, etc) so am looking at a 0-200 MICROamp output signal that is available off of the temp control black box (proportional to the input t/c signal) that I could use for monitoring. How in the world can I convert or get a 0-200 microamp signal in to a PLC?
RE: Convert a 0-200 Microamp Signal for use in PLC?
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RE: Convert a 0-200 Microamp Signal for use in PLC?
RE: Convert a 0-200 Microamp Signal for use in PLC?
TTFN (ta ta for now)
I can do absolutely anything. I'm an expert! https://www.youtube.com/watch?v=BKorP55Aqvg
FAQ731-376: Eng-Tips.com Forum Policies forum1529: Translation Assistance for Engineers Entire Forum list http://www.eng-tips.com/forumlist.cfm
RE: Convert a 0-200 Microamp Signal for use in PLC?
I suggest isolated inputs on temperature transmitters, because many commercial thermocouple junctions are grounded and grounding can produce ground loop problems; an isolated transmitter input avoids that issue.
There are two categories of temperature transmitters - dumb and smart. The dumb transmitter is factory configured for some input range, say, 0-500 Deg F. with a corresponding proportional 4-20mA output.
The smart transmitter's input can be configured zero/span for the 4-20mA output. Problem is, unless you're in an industry where the software/modem or handheld programming communicator is readily available, then you're stuck buying and learning whatever gear is needed to set the range.
A dumb transmitter should be pre-ranged; my recommendation for a smart transmitter one is to find a vendor who will configure the range for you so you don't have deal with the configuration end.
It pays to physically label a field transmitter with its configured input range so the next guy knows what the 4-20mA output signal represents.