Watlow Series 935B Manual de usuario descargar pdf (Pagina 34)

34 Watlow Series 935B User’s Manual

Auto-tuning

Manual Tuning

For optimum performance, tune the Series 935B to your thermal system.

The settings here are for a broad spectrum of applications;

your system may have different requirements.

Tune heating outputs at a set point above ambient temperature.

Tune cooling outputs at a set point below ambient temp.

1. Apply power to the 935B and enter a set point.

In the Operations Menu, [`Aut] must = [``no].

Begin with these Configuration Menu settings:

[Pb`h = [```1], [``1t] = [`000], [``dE] = [`000],

[Ct`h] = [``50], [`CAL] = [```0].

2. Proportional Band Adjustment: Gradually increase [Pb`h] until the upper

display temp. stabilizes at a constant value.

3. Integral Adjustment: Gradually decrease [``It] from 30.00 until the dis-

play temperature begins to oscillate or “hunt.” Then slowly increase

[``It] until the upper display stabilizes again near set point.

4. Cycle Time Adjustment: Set [Ct`h] as required. Faster cycle times some-

times achieve the best system control. However, if a mechanical contactor

or solenoid is switching power to the load, a longer cycle time will mini-

mize wear on relays.

5. Derivative Adjustment: Increase [``dE] to 0.10 minute. Then raise set

point by 20° to 30°F, or 11° to 17°C. Observe approach to set point. If load

temperature overshoots, increase [``dE] by 0.50 minute. Raise set point

by 20 to 30°F, or 11 to 17°C and watch approach again. Repeat until sys-

tem rises to new set point appropriately.

6. Calibration Offset Adjustment: Enter the [`CAL] offset value you want.

Calibration offset adds or subtracts degrees from the value of the input

signal.

Auto-tuning the Series 935B

Auto-tune automatically sets PID parameters for your system.

1. Press . and , for three seconds.

2. You'll see [`Aut

3. Press and hold ß, then select [`YES] with . or ,.

[tune]

will

flash to indicate auto-tuning. Display reverts to normal after auto-tuning.

4. [`Aut] = [``no] stops auto-tuning.

NOTE:

[`Aut] is

not visible at

factory default.

CAUTION:

Successful Series

935B auto-tuning

requires 3 oscillations

thru the 90% set point

in 85 min. or less. If the

system cannot perform

the oscillations in that

time, the control will

revert to the previous

PID values.

NOTE:

Manual tuning is a slow

procedure, taking from

minutes to hours to

obtain optimum value.

Figure 7 - Auto-tuning the Series 935B

Temperature

Time

90%

Set Point

Operations Menu

[`Aut]

✓

Auto-tune

[`ALO]

Alarm Range Low

[`Ah1]

Alarm Range High

[tMr]

Countdown Timer

[IdLE]

Idle

[`L-r]

Local / Remote

[`Pid]

PID

[CnFg]

Configuration

Auto-tuning occurs at 90%

of set point in less than or

equal to 85 minutes ç

1 2 ... 29 30 31 32 33 34 35 36 37 38 39 ... 59 60

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Watlow Series 935B Manual de usuario Pagina 34

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