Alarm Configuration

It depends on what guidelines your plant you are following and you are the only one knew it.

An alarm system is just a discrete analog I/O you may have it a single loop circuit or integrated to PLC or DCS.

You have options also to incorporate it to the old DCS via analog I/O module.

Or you may reprogram ladder on your dcs and provide discrete output module for separate annunciator.

As is usually the case... the answer to this is not so cut and dried as you may think. Currently, the ESD system passes on the change in I/O data to your DCS.

Making this change will cause no issues for the ESD system, however, as your "whole" system consists of the ESD and the DCS system, no one but a person who fully "knows" and understands the entire system architecture can comment on whether or not this proposed change will perhaps introduce a failure mode that was not anticipated.

Do not make this change... until any linkages that may be impacted are "fully" understood.

As always, a lot of questions with little information.

• Does the ESD automatically shut down the equipment or is it a visual / audible alarm where it needs an operator to intervene and shut it down?
• Why the recommendation to separate the alarms?
• I don't see it as a violation in standard electrical practices, however if it also runs through the E-Stop circuit, you may need to modify that too?
• Where is this located, Country, City?
• What are the electrical code requirements?
• The more information the better!

Jose, what type of equipment are you talking about? does this have anything to do with a steam turbine or anything to do with Level Transmitter -Radioactive?

Being that I'm not there Mumbai, I am not familiar with your codes or what kind of equipment this alarm system is connected to, it would be irresponsible for me to make any recommendations.

The electronic RS-485 link that communicates the alarm signal to the DCS should be electrically/optically isolated between the alarm generator and the DCS to minimize the probability of an electrical fault on the DCS side from destroying the ability of the alarm generator to function normally. Same concept as an I/S barrier protecting the I/S instrument in the hazardous area from an electrical fault in the safe area.

• Does the ESD automatically shut down the equipment or is it a visual / audible alarm where it needs an operator to intervene and shut it down? Auto Shut down
• Why the recommendation to separate the alarms?, Based on SIL Report
• I don't see it as a violation in standard electrical practices, however if it also runs through the E-Stop circuit, you may need to modify that too?
• What are the electrical code requirements? NEC 70, cL 1 , div 2
• The more information the better!
• The more

7000 HP pump motor, I am refering to pressure transmitter

First: It looks as if the alarms are High, and High-High, not Low and Low-Low; although it is a little hard to be sure from the bit map you posted.

Second: If you have a "SIL Report" recommending the separation, why are you polling internet strangers to fight the idea?

I think you answered your own question. If the SIL report recommends you separate the alarms, You should follow their report and do it!

Having a SIL Report or not... "No" changes to this control system should be made by anyone! Until such time as the full impact of ANY change is fully understood completely.

Doing otherwise is reckless in the extreme. I would sure hate to dead end the output from a 7000 HP pump because some timing issue was not addressed properly by way of this "minor" change!

Do the legwork first!

Hello josej,

Your statements are not very clear. Do you have a pressure transmitter connected to both your ESD and DCS? Or is it a pressure switch? If it's a pressure switch, does it have two settings? One for low alarm and one for low-low alarm?

It's a little hard to provide answers if the original question opens up more questions.

regards,

Vulcan