Honeywell TDC 3000 problem

[Chambers1989]

Hello,

I am wondering if anyone can help solve a problem we are having at my place of work.

We are currently having problems with some inputs to our DCS system, Honeywell TDC 3000.

All affected transmitter inputs go into one marshalling panel which houses F.T.A cards which go to two different A.P.M's. Inputs which are being handed off to both A.P.M's are problematic.

The displays for the affected loops all seem to be showing a bad PV when at there lower feedback levels. Once you simulate higher mA's the displays start to read. This problem is affecting control loops for flow transmitters, pressure transmitters, temperature transmitters and level transmitters so it is not as if it is a certain type of control loop being affected.

If you break the circuit momentarily and then re-instate it, the loop will still show bad PV as it did before. But if you leave the loop powered down for a longer period of time, when you re-instate the loop, the problem will clear for a few hours.

Has anyone on this forum ever came across problems with the same sort of symptoms as we are having?

Cheers,
Matthew Chambers

 

[DRWeig]

FTA? APM?

Best to you,

Goober Dave

Haven't see the forum policies? Do so now: Forum Policies

 

[VEBill]

APM = Advanced Process Module ?
FTA = Field Termination Assembly ?

Ground drift? (<- warning, pure speculation)

 

[danw2]

>But if you leave the loop powered down for a longer period of time, when you re-instate the loop, the problem will clear for a few hours.

Sounds to me like something in the front end circuitry cools off over time when it's powered down, letting the AI drift back into operational spec and then it works like it should until it overheats during operation.

Anyone checked the air filters on the panels?

How's the air conditioning for DCS racks? Are you trending panel temperatures?

Have you measured the power supply voltages for the AI input cards?