Need Help Installing Rosemount O2 Transmitter

[mihail]

Hello Everyone! I just installed a new Rosemount X-Stream O2 Flue Gas Transmitter in our boiler and cannot get it to work. The loop is connected this way: Analyzer positive to Foxboro 760 controller positive, Foxboro 760 negitive to chart recorder positive, chart recorder negitive to analyzer negitive. I have tried adding a 24VDC power supply to this loop but it did'nt work. I then removed the power supply. I then tried a Junxta 4-20mA to 1-5VDC signal conditioner at the 760 input and did finially begin to get a mA signal but then the chart recorder began painting. Has anyone seen something like this before? Mihail

 

[John Soltesz]

I believe that this is a loop powered transmitter. As with all loop powered devices you need to include power, typically 24vdc. Note polarity! This is standard stuff for loop powered devices. Does the transmitter need to be setup first to output the process variable you need? Are the other devices setup for 4-20ma loop input? Do any inputs need an external resistor across the input? Insert a ma meter in the loop and what do you get?

 

[mihail]

John, I set the transmitter up and calibrated it by putting only the transmitter and power supply in the loop. The transmitter worked great that way, but when I put the controller and chart recorder in the loop as you have shown then nothing works and all I see with my meter is 1.70mA. I know it is wired correctly. I took the power supply out and added a Junxta signal conditioner (4-20mA to 1-5VDC) at the controller input and now I get a reading of around 10.50mA but now the chart recorder and controller are swinging together so I know this is not right. I should see a pretty steady reading on the recorder and controller.
There is a 250 ohm resister across the + and - of the chart recorder so it is set up for 1-5VDC. I'm not sure about the controller, I will need to slide a mirror under it to see whats there but I did try two differwent Junxta's at it's input - one 4-20mA to 4-20mA and the other 4-20mA to 1-5VDC. With the last one I got a reading, but I know it's not right.