Emerson Exchange 365

Dear Experts

As Cecil L. Smith defined in your book for the use of Error Gap Algorithm for Level Control. The objective is to achieve the following:

Normal operations. Use a low controller gain so that the controller output changes only in a gradual manner that does not upset the downstream processing units.

Major upset. When the level reaches the limit of the gap, switch to a high controller gain so that the controller will make the rapid changes required to prevent the level from exceeding the limits imposed by the level switches.

The level set point, the error gap, and the controller gain are adjusted so as to achieve the following:

1. Controller output will attain 100% (full discharge fl ow) before the level attains the location of the high-level switch.
2. Controller output will attain 0% (no discharge fl ow) before the level attains the location of the low-level switch.

My questions are follows: 

• How can I implement this algorithm in DeltaV ?
• What it is the PID block function to carry out this algorithm?
• I found this reference (see figure) so I wonder if this PID module be able to carry out this algorithm?

I look forward to your advice and comments

Thanks in advance

Best regards

Rodrigo Sandoval López | Control Systems and Instrumentation Engineer