AB SLC 1746-NI16I & Lightning

[DenverGreg]

We've recently installed a wellfield monitoring building
with a SLC 5/05. The SLC monitors 19 dewatering and recharge
well levels (4-20mA downhole pressure transducers).
The channels on the 1746-NI16I modules have now begun
drifting and/or not working at all (reflecting 21 mA input).
The shielded, direct-buried cables to these wellheads varies
in length from about 200' to the closest well to 1600' to
the farthest. The drain wires are grounded at the PLC panel
only.
We've had some pretty wicked lightning storms and are
attributing the input problems to this. I've received
new NI16I modules from AB and I am going to add some
surge protection. I have 1/10 amp fuses on the 24+ going
out to the transmiters for amperage spikes already , but I
would like to add some TVSS.
What experience has anyone had with Phoenix's PlugTrab
or Transtector's DRDC series? And also... has anyone had
problems like this with the 1746-NI16I modules? I've used
1771-IFEs almost exclusively over the last twenty years and
cannot recall a single instance of this happening.
Thanks in advance.

 

[504bloke]

You may want to try and re-calibrate the NI16.

This may be of help.

See Appendix D of the user manual.

And nope, i have never had any problems with the NI16. Although i always have a calibrate routine written so when the customer has there instruments calibrated they can also have the company calibrate any NI16's or BTM's through a panelview calibrate screen.

 

[DenverGreg]

Dave,
I've tried recalibration and a few of the points didn't calibrate. In fact, they would not even complete the loop when the calibrator was attached. I dis-abled the three channels, the green lights went steady,
and the remainder of the module points are reading fine. It appears
as though the module has lost it's isolation on those points.