Re: [foxboro] Analog input current about 2% low
- From: "Ali Ahmed" <alizahidi@xxxxxxxxxxx>
- To: foxboro@xxxxxxxxxxxxx
- Date: Sat, 13 Jan 2007 09:56:10 +0000
Try some other test equipment on the bench to verify the transmitter output
current. somtimes your test equipment malfunctions and needs calibration.
Rgds,
Ali Ahmed Zahidi
Pakistan Refinery Ltd.
Karachi, Pakistan.
>From: brad.s.wilson@xxxxxxxxxxxxxx
>Reply-To: foxboro@xxxxxxxxxxxxx
>To: foxboro@xxxxxxxxxxxxx
>Subject: [foxboro] Analog input current about 2% low
>Date: Fri, 12 Jan 2007 05:24:44 -0600
>
>We have a perplexing problem. One 4-20 mA input on a FBM04 is reading
>consistently lower in the AIN block than at the transmitter. The AIN is
>set for SCI=3 (4-20 mA) with KSCALE=1 and BSCALE=0. We've bench-tested the
>transmitter (Rosemount 3051) and it is right on the money, both with the
>HART and independently measuring the current output. What I see in the AIN
>is that both the RAW counts and the MEAS values are showing 0.8 psi lower
>than the transmitter (this is about 2% of scale). The odd thing is that
>this is across the range, so it looks like a bias. We've replaced the FBM
>and the problem is still there. We're going after the nosecone next.
>Could there be a drain in the wiring, like a poor termination, that would
>show a constant reduction in current? Anybody seen anything like this
>before?
>
>Brad Wilson
>Process Control Engineer
>ExxonMobil Chemical Co
>Edison Synthetics Plant
>732-321-6115
>732-321-6177 fax
>Brad.S.Wilson@xxxxxxxxxxxxxx
>
>
>
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