Honeywell UDC 3300 manual Appendix a Manual Tuning

Section 11 – Appendix A – Manual Tuning

11.1 Overview

Introduction

Tuning technique

Controller tuning procedures

Tuning aids

When you tune a controller, there are some things to consider:

•Process Characteristics - Gain, Time Constants, etc.

•Desired response - Minimal overshoot

Basically, controller tuning consists of determining the appropriate values for the Gain (PB), Rate (Derivative), and Reset (Integral) time tuning parameters (control constants) that will give the control you want. Depending on the characteristics of the deviation of the process variable from the setpoint, the tuning parameters interact to alter the controller’s output and produce changes in the value of the process variable.

Since each parameter responds to a specific characteristic of the deviation, you may not need a combination of all three. It depends on the process characteristics and the desired control response.

You can estimate a starting point and the tuning parameters required to give the desired controller response and with some experience become proficient with this method.

An alternate approach is to rely on a tuning technique. In practice, tuning techniques usually do not give exactly the type of response desired; thus, some final adjustments to the tuning parameters must be made.

However, you should at least obtain a reasonable starting point from which the desired response characteristics can be obtained.

There are three procedures for tuning the controller:

•Time, Position, or Current Proportional simplex control,

•Duplex Time or Current Proportional control,

•Two sets of tuning constants for single output operation.

The suggested procedures describe how to establish and store values of Gain (PB), Rate, and Reset time constants for your process. You must know the type of control and algorithm your controller has.

A graphic recorder (such as Honeywell model DPR, DR4500, or VP131) connected to the process variable will make it easier to determine when the oscillations are constant and also the time for one oscillation. If a recorder is not available, you can use a stopwatch to time the oscillation of the process variable displayed on the controller.

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