Signal Corruption

I'm needing a little assistance.
I have a Rosemont Pressure Transmitter and a Flow Meter with Transmitter both 4-20ma. These are on a Fresh/Salty Water well at our plant. These instruments were working fine until we replaced the 125HP submersible motor down hole.
The pt reads correctly on the transmitter but the signal to the PLC is increased. The same on the ft but the issue is much more prominent.

While the pt is connected to the piping system my Hart meter will not recognize the pt. If I disconnect it from the piping it works correctly (Hart meter). Also when I disconnect it the flow meter inaccuracy increases.

We have isolation kits on both sides of the instrumentation section. Also I have a isolation union on the pt.

We have run a triad for the grounding on our system, keeping the PLC on an isolated ground.

Tried new instruments to no avail.

The Pump installers gaurentee that the motor was grounded.

We have a VFD for the pump (same one) with Line and Load reactors. The readings are correct while the pump is off.

Any ideas or thoughts on where to start looking? Or a way to Prove where the issue is coming from.

I know based on what the symptoms are and when it started it would appear to be the new pump, but how can I prove this technically so I can present the facts?

have you checked for noise on the signal wiring while pump is running, then checked for same when the pump isn't running to measure the difference?

1) What is a "HART meter"? A handheld HART communicator or something else?

2) The pressure transmitter is loop powered.

a) Is the pressure transmitter loop power supply's DC output grounded on either leg or floating?

b) Is it an 'independent' power supply or integral to the PLC?

3a) What technology is the flow meter?

3b) Is the flow meter loop powered? or is the flow meter's 4-20mA output loop powered or is it "active", powered by the flow meter?

4) >The pt reads correctly on the transmitter but the signal to the PLC is increased.

I assume that this means that the digital display reading on the PIT's integral meter is different than the interpretation of the 4-20mA signal display by the PLC.

a) Is that a correct assessment?

b) How big is the error?

c) Is the error constant or does it change in magnitude?

d) And as Katratzi asks, is the error the same when the pump is powered as when the pump is off?

5) >We have isolation kits on both sides of the instrumentation section.

a) What is an isolation kit?

b) "both sides of the instrumentation section" means what?

6) >isolation union on the pt.

a) This is a pipe union, with a plastic insert to electrically isolate one side of the union from the other. Correct?

The HART 'meter' failed to read the PIT with the isolation union installed ?

7) >We have run a triad for the grounding on our system
>when it started it would appear to be the new pump

How many things changed when the pump was installed?

Was the triad grounding changed when the new pump was installed?

Were the power cables between the VFD and the motor replaced?

What else?

8) Where do the flow and pressure signal wires run in relation to the cables between the VFD and the motor?

Is the signal cable screen grounded at ONE end only? Is the signal 0-10V, 1-5V or 4-20ma? 4-20ma is best for rejection of injected noise and voltage. Voltage signals are easily increased and show error far easier than 4-20ma signals from voltage injection.

That's correct. Grounded only at the Plc side not the instrument. It is a 4-20 mA circuit.
I'm on the road but I'll try and answer all these questions.

Isolation kits isolate the piping from the pump side and another one after the instruments to keep them isolated from any signal from the pipe.

Yes a hart communicator.

Nothing else changed.

Power lines were megged and are fine.

How can I check for noise on the control wiring?

Yes pipe isolated union was in place when test with the hart.
I believe the salty water is conductive rendering the iso kits useless.

Power supply is the same as the Plc.

We have several of the same setups and this is the only one with the issue.

Hope I answered all the questions