Red-lion PCU Manuel d'utilisateur télécharger pdf (Page 73)

As shown in Figure 37, Auto-Tune Operation, Auto-Tune cycles the

process at a control point 3/4 of the distance between the current process

signal value (at the instant Auto-Tune is started) and the setpoint. The 3/4

controlpointwasselected to reducethechanceof signal overshootatsetpoint

when Auto-Tuning at start-up. If Auto-Tuning from setpoint and signal

overshootisunacceptable,temporarilylowerthesetpointbyanamountofthe

oscillation and then Auto-Tune. Reset the setpoint to the original value when

Auto-Tune is complete. After starting Auto-Tune, the secondary display

indicates the current phase (Aut1, Aut2, Aut3 & Aut4). If the controller

remains in an Auto-Tune phase unusually long, the process or connections

may be faulty. Additionally, during Auto-Tune it is important that

disturbances to the system be minimized, as these may have an effect on the

parameter determination.

INITIATE AUTO-TUNE

Auto-Tune may be initiated at start-up, from setpoint, or at any other

process signal point.

To Initiate Auto-Tune:

1. Make sure that Auto-Tuning is enabled in parameter lockouts module.

2. Place the controller into the normal display mode.

3. Press PAR for 3 seconds from normal display mode.

4. Scroll to “tUNE” by use of PAR, if necessary.

5. Select “YES” and press PAR.

Auto-Tune is initiated.

To Cancel Auto-Tune: (Old PID settings remain in effect).

A) Make sure that Auto-Tuning is enabled in parameter lockouts module.

1. Place the controller into the normal display mode.

2. Press PAR for 3 seconds from normal display mode.

3. Scroll to “tUNE” by use of PAR, if necessary.

4. Select “NO” and press PAR.

5. Auto-Tune canceled.

B) Or reset the controller by disconnecting AC power.

Note: If using the linear DC output for control, full power is applied (+100% OP1

or -100% OP2) regardless of the output power limit settings. Set the Linear DC

Output scaling points to limit the magnitude of the output, if desired.

AUTO-TUNE OF SECONDARY OUTPUT (OP2) / MAIN

OUTPUT (OP1) SYSTEMS

During Auto-Tune of OP2/OP1 systems, the controller switches the

secondary output (OP2) on and off in addition to the main output (OP1). The

deadband parameter (db-2) determines the amount of overlap or deadband

between the two outputs during Auto-Tune. Refer to ON/OFF CONTROL ,

page62,forthe operation ofthisparameter.The deadband parameterremains

unchanged after Auto-Tune is complete. Therefore, when proportional

controlis startedafter thecompletion ofAuto-Tune, thisparameter mayneed

to be reset.

Itisimportantthat external loaddisturbancesbeminimized, and ifpresent,

other zone controllers idled as these may have an effect on the PID constant

determination. The controller additionally sets the Relative Gain parameter

(GAN2) for OP2/OP1 systems.

AUTO-TUNE OF INTERNAL CASCADE CONTROLLERS

Auto-TuneofInternalCascadecontrollersinvolvestuning ofthePrimary

PID and Secondary PID parameters. Each set of parameters is tuned

individually with the secondary parameters normally tuned first. For

Internal Cascade controllers, Auto-Tune offers the option of tuning the

Primary or Secondary:

tunE

– No Auto-Tune or abort Auto-Tune

Pri

– Start Auto-Tune of primary or Auto-Tune of primary in

progress

SEC

– Start Auto-Tune of secondary or Auto-Tune of

secondary in progress

The Auto-Tune status display indicates the set of parameters actively

Auto-Tuned:

TunePhase

Display

(Primary)

Display

(Secondary)

1 APr1 ASC1

2 APr2 ASC2

3 APr3 ASC3

4 APr4 ASC4

-65-

1 2 ... 68 69 70 71 72 73 74 75 76 77 78 ... 95 96

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Red-lion PCU Manuel d'utilisateur Page 73

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