Re: [foxboro] Rate of Change Alarming
- From: "Wilson, Brad" <brad.wilson@xxxxxxxxxxxxxxxx>
- To: <foxboro@xxxxxxxxxxxxx>
- Date: Fri, 4 May 2007 11:07:33 -0400
I just did a test with a RAMP and REALM and it worked as expected. The
trick is to get the units correct ... the RAMP.OUT is units/min and the
REALM.ROCVAL is units/sec. When I RAMPed at 50 %/min it showed up on the
REALM.ROCVAL as 0.833 %/sec.
In your case I would try
Make your REALM input scaling the same as the AIN that feeds it
REALM.ROCLIM =3D 1.67 (deg F/sec or 500 deg in 5 min)
REALM.ROCTIM =3D 5 (mins)
REALM.ROCOPT =3D 1 (enable ROC alarming)
Now, this will alarm if the instantaneous rate ever goes over 1.67
deg/sec. ROC alarming is absolute value, so you'll also get an alarm if
it falls 1.67 deg/sec. You might be able to "dampen" the alarming by
using a filter in the AIN block, but that is questionable.
Brad Wilson
brad.wilson@xxxxxxxxxxxxxxxx
Invensys Systems, Inc
1090 King Georges Post Rd, Suite 204
Edison, NJ 08837
732-874-0087
-----Original Message-----
From: foxboro-bounce@xxxxxxxxxxxxx [mailto:foxboro-bounce@xxxxxxxxxxxxx]
On Behalf Of Jaudon, Mike
Sent: Friday, May 04, 2007 10:40 AM
To: foxboro@xxxxxxxxxxxxx
Subject: [foxboro] Rate of Change Alarming
List,
=
Can anyone tell me how and what to set on a REALM block to make the ROC
work? In the past I have set up on a test bed and used a RAMP block to
test but it never works as I think it should.
=
I want an alarm to be generated when the temperature goes up 500 DegF in
5 minutes. The temp normally operates at a constant value but if it
increases by the 500 Degrees within 5 minutes then I want an alarm.
=
In the past I have accomplished this by building two AIN blocks and
changing the "period" on one and sending these to a REALM block (MEAS &
DEVSPT). One problem I have now is there is no period with a 5 minute
execution. Besides if I could configure the REALM correctly I would
only have to create one block instead of two.
=
Anyone with any ideas?
Michael L. Jaudon =
TRONOX, LLC =
(Technology Group-Hamilton, MS) =
(662)343-8710 Office =
(662)304-0313 Cell =
mike.jaudon@xxxxxxxxxx =
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