Analog Output Point in Honeywell DCS

To avoid damaging the unit....

Can you be specific what will happen?

No....but these guys might know....↓

http://hpsweb.honeywell.com/Cultures/en-US/Support/default.htm

Speculation on my part because I don't have access to a Honeywell DCS, but there's clues.
I suspect that an analog output will not sustain any physical damage. DCS hardware is pretty robust and most current AO's can regulate its output across a short circuit and not whimper.
AO's do things like drive valves, VFDs and damper drives and the loss of a valid drive signal should be an alarmable event.
A DCS is very alarm intensive by design. So I suspect that the "disable/inactivate" requirement is probably related to the probability that the DCS will detect an open circuit on the AO when the wires are removed and trigger an alarm.
Along those lines, Honeywell's XYR6000 wireless clearly has links to their DCS, as evidenced by earmarks like the necessity to configure any point into OOS (out of service) mode before making any changes. Iris

Thanks for the reply. Your assumption might be correct. when we remove any AO point wires defenitely DCS will create an alarm. My concern is what else will happen other than this alarm. Normal alarm does not make any effect on system. So other than this alarm any severe problem could happen or not?

What did Honeywell say in response to the telephone call?

Honeywell DCS output cards especially the older ones have a habit of putting out a card failure signal and dropping the other outputs on the card to zero. ie entire card can go belly up even though only one output should show to be faulty.

As you should know this is a bad thing if it is controlling a large process and I know because I have done it, it dropped out a 200t/h steam boiler. All the outputs went to BP(bad point)and I went to the dog house.

I agreed with you. Once we got the same problem when we removed an analog output with out inactivating the point, all the outputs connected to that particular card has got initialized on its controller. But we could returned back that loop immediately and saved the other controllers. Now i need to know that how the card detects the failure of one output and putting other to a initialized condition?

Hi,

inactivating an analog output point is not "required" before disconnecting the wires, but you will get a system status alarm when the wires are disconnected. No damage will occur.

Thanks

Positioner of any control valve or other controller reports the position of that particular controller. If you open the wire connected to positioner without proper precaution, the controller may get confused about its position and in turn it will malfunction, either fully open or close.