GE AT868 AquaTrans Ultrasonic Flow Meter

[ShajiNarayanan]

Hello

I am facing some issues with our 8 GE AT868 AquaTrans Ultrasonic Flow Meter (Water Flow).

Using Channel 1 and 4-20 Analog Output to interface DCS/PLC.

The Flow showing in (GPM) Local Instrument LCD and the current output from the AO is not matching.

Done AO Calibration, and Liniarity check. While checke/Simulate it will generate exact current, but it put back, it will generate wrong AO.

Out of 8 Instruments, 4 are ok.

Please suggest a solution.

With Regards

Shaji Narayanan

 

[danw2]

It's a 4 wire transmitter, so my first suspicion was that the error was due to a ground loop, but the manual claims that the output is isolated (pg 16 pdf). So, if they claim isolation, then we'll believe it for them moment.

For reasons beyond me, there is a warning about not connecting an ammeter directly across the analog output terminals. I can't imagine, why one shouldn't. How can current meter load a current circuit?

If you followed their AO cal procedure, which uses 4.0 mA at the low end, not 0.0mA, then you should be smack on assuming you're using 4-20 on the DCS side.

You do not say what the magnitude of the error is (how big the error is). How big is the error?

How you are determining the error? With the ammeter in the circuit? Or by what DCS reading is?

 

[ShajiNarayanan]

Hello Danw2

Thanks for your time.

As I mentioned we are using 8 Transmitters, out of 4 are ok.

The Transmitter has its own LCD Display, it shows 230 GPM based on our scale (0-500 in both meter/dcs) based on the scale we are getting less ma in Ammeter as well as in dcs. 180 GPM in DCS.

While doing the AO Calibration Transmitter generates correct ma, but it goes back on exist of that funtion.

Issues are with 4 transmitters, so not assuming that some thing fault on it.


With Regards

Shaji Narayanan
Muscat - Oman

 

[ShajiNarayanan]

Hello Danw2

I solved the issue.

It was not related to any AO calibration.

AO channel was configured to Channel 1 only. but the LCD display parameter configured to average of volume (CH1_flow+CH2_Flow)/2.

Thanks again for your time

With Regards

Shaji Narayanan
Muscat-Oman