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from the instrument and control department...
Analog signal simulation
Process Control topic
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Posted by yazan on 28 March, 2008 - 11:23 pm
How can I make a simulation or forcing for an analog signal (like pressure) in the Speedtronic?

Posted by CSA on 29 March, 2008 - 12:29 am
Mark II Speedtronic? Mark IV Speedtronic? Mark V Speedtronic? Mark VI Speedtronic?

Posted by CTTech on 30 March, 2008 - 3:20 pm
Let me see?
If you have a Mark I and study the P&ID closely, one can find the ice cube relay(s) that operate the analog control output devices such as an IGV or the fuel control valve.

If you have a Mark V and study the CSP closely, one can find the logic point(s) that operate the inlet bleed heat valves or other pnuematic devices.

Forcing generally refers to logic(binary).

Simulation generally refers to analog.

If one what to simulate an analog input, disconnect the wires and attach a device capable of producing the proper output.

Even better!!! Actually simulate the input pressure to a device with a pressure calibrator. WOW; we actually calibrated at the same time.

I have a question. Does anyone do any research on the problem before posting a question that cannot be answered with the provided information?

Posted by CSA on 31 March, 2008 - 11:42 pm
CTTech,

You saw the originator did not reply with the correct information; rather a new query was posted (under the same title as the previous post!) with just a little bit more information.

Actually, analog values can be "forced" (that's actually the terminology being used so as not to have to come up with another term) with Mark VI, though I believe the designers wished they hadn't done that. A couple of units have had some pretty serious damage caused by analog forcing of critical parameters while the unit was running. "Hey! It didn't stop me from doing it!" was one justification for forcing the values.

The rest of the response should have been "...from doing something totally idiotic!"

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