DVC control issue

DCS
1

A bit of a valve/ control question. Anyone out there running the newer Experion system on your DCS and also have a fair amount of DVC 6200 that operations like to keep clamped at -5%?

If so we had an issue where one of out DVC’s was failing causing the DCS to go into an initialization error which in turn prevented the board guy from making SP changes from the DCS. So when we troubleshot it we noticed that the mA value was 3.2 which struck me as weird. Also when the power was cycled the positioner would work.

So has anyone had or seen a similar issue?

2

In Yokogawa Centum VP DCS software also has the same issue/feature.

The configuration in the PID block is such that when the valve is at 0% position then the output is below 4 mA.

The PID controller output current increases after the setpoint above 2%, 4% like that. (then only positioner changes its output)

We changed the setting in the PID then only the issue was solved. (Actually, we don’t need this option).

You can solve the issue with PID controller settings in DCS.

You can verify the 4mA DCS output when the valve is at 0%. Check whether you are getting 4 mA or not when the PID controller MV is at 0%.

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3

This option is for tight shut-off of control valves. (in Yokogawa)

Just disable this option in PID block properties.

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