Calibrating a Rosemont 3051

B

Thread Starter

Brian P.

I'm having trouble trying to calibrate a rosemont 3051-S for a small open top tank to output 4-20ma to an analog input card on a PLC. This is for a college project and I don't have much experience with this stuff, so bear with me:). The transmitter is hooked to the analog card with a 24v power supply in series. The card has an internal 250 ohm resistor.

I've tried calibrating it with a fluke 745 calibrator and also AMS software so far.

The tank is 28" above the transmitter connected to the high side, and the low side is vented. The transmitter comes calibrated for -250 to 250 inh20. Basically the problem is I'm only using a small portion of that span, and it doesn't seem to let me calibrate a new zero. But I'm not sure I'm doing it correctly.

I made a new LRV of 28.0" and URV of 48.0" which corresponds to the range of water that can be in the tank, but the analog signal changes very little over this range. It's something like 7.9mA at 0% and 8.6ma at 100%. IF I try to re-zero, it gives an error saying the correction is too large?

Even with the LRV and URV I made, the span is still listed as -250 to 250 in H20. Does anyone know where I can get step by step instructions for this?
 
Hi,

here are a few things you could check:

Have you remembered to press the "Apply" button on the AMS?
If the calibration of the cell is OK, it should output 12mA when no pressure is connected, if the LRV and URV are as you say; try to check the "Process variables" screen in AMS with various input pressures.
Another thing to check is the transfer function, should be linear.
I always try to reset the transmitter to the factory trim if I come across problems. You will find this function in the "Action" menu -> Methods -> Calibrate -> Recall factory trim.

Geir
 
Send me a mail and I will send you a detailed explanation and a drawing on how to do this. Send as much info and explanation of what you are trying to do and attach a detailed drawing of your application to your mail if possible.

This offer is open to anyone having trouble with DP level calibrations including capillary types on high pressure vessels, wet and dry legs, measuring the levels of liquids with unknown sg's like waste products, vacuum or steam application and so on.

The more info you supply the better I will be able to help. a Drawing is normally much easier to understand than a long explanation.

Sam
[email protected]
 
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