I should have mentioned the transducer was at 0 psi and the 24vdc power supply is at that end. Originally the transducer was in series with a PLC at the pressure tester and the interface in the QC (quality control dept.)office.
When both were hooked up, the PLC at the tester would read 10x the tranducer's max rating (65000psi) of 400bar (6000psi). I teed off the pressure line and added a second transducer to feed the QC interface.
I am keeping the fluke and interface in series. When just the fluke is in series I get 4mA steady, when I add the interface in series as well the reading jumps up to 7 to 9 mA and isn't steady. 7 for a minute or so, then 9 for the same and back. I can't figure out where the extra amperage is coming from.
The next steps are to:
-hook up a scope
-use a separate 24vdc supply
-put in a bridge rectifier
-your 4-20mA source idea (the fluke has one, and we have more flukes)
-run a new cable (temporarily over coat hangers)
I am on vacation next week. This problem started 4-6 months ago, and now it's my turn to tackle it. I have already spent quite a few hours on it, but can't seem to narrow it down. The electrical dept. keeps wanting to blame the interface, but I don't think that is the problem. There is a 300 page manual with it but no schematics.I'm afraid to go there.
I have tried 2 other transducers, and tested them by getting a 0 psi reading from the PLC readout panel (Magelis and Panelview) on the other testers.
When the fluke and interface are both in series they both read 7-9 mA. When just the fluke is in series it is 4mA steady.
I would think that adding the interface in series would raise the impedance and lower the current?
Edited because I remembering more stuff. My notes are at work.
[This message has been edited by Pinemarten (edited 08-24-2003).]
[This message has been edited by Pinemarten (edited 08-24-2003).]
[This message has been edited by Pinemarten (edited 08-24-2003).]
