Dual 4-20mA signal but need a single 4-20mA signal output
Dual 4-20mA signal but need a single 4-20mA signal output
(OP)
Big picture question on instrumentaion logic. My existing setup is a single level transmitter (4-20mA) feeding circuit via a controller. To avoid a failure of the circuit, we would like to add a second level transmitter (so that one LT fails, the other will continue to work and feed the controller and its circuit). However, the controller circuit is too complicated, we would like to do the following:
Take 2 LT inputs (2 x 4-20mA), run it through a black box. Out from the black box, we need a single 4-20mA signal for the controller and the downstream circuit. The black box should be also able to know a failed LT (fail low or fail high or power supply failure) and switch to the working transmitter automatically.
Is such black box device possible? Is anything commercially (readily?) available? If so, please provide the detail.
I appreciate all inputs and responses.
(PS: Controller failure is also similar to the LT failure; but at this point we want to make LT fail proof and worry about controller later)
Take 2 LT inputs (2 x 4-20mA), run it through a black box. Out from the black box, we need a single 4-20mA signal for the controller and the downstream circuit. The black box should be also able to know a failed LT (fail low or fail high or power supply failure) and switch to the working transmitter automatically.
Is such black box device possible? Is anything commercially (readily?) available? If so, please provide the detail.
I appreciate all inputs and responses.
(PS: Controller failure is also similar to the LT failure; but at this point we want to make LT fail proof and worry about controller later)
RE: Dual 4-20mA signal but need a single 4-20mA signal output
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: Dual 4-20mA signal but need a single 4-20mA signal output
Link to STA spec sheet: Link
app note on web page: Link
RE: Dual 4-20mA signal but need a single 4-20mA signal output
RE: Dual 4-20mA signal but need a single 4-20mA signal output
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: Dual 4-20mA signal but need a single 4-20mA signal output
RE: Dual 4-20mA signal but need a single 4-20mA signal output
Probably because the alternative of PLC availability.
There is the path of using a DPDT relay with gold plated contacts. But you need some discrete signal to drive the coil with.
RE: Dual 4-20mA signal but need a single 4-20mA signal output