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5. Press the Return Key for at least 6 seconds (maximum 16 seconds), then release. This enters the
low calibration figure into the controller’s non volatile memory.
6. Press and release the Scroll key. « HCAL » appears on the PV display. This indicates the high calibration
point.
7. Increase the simulated input signal to coincide with high process signal (e.g. 100 degrees).
8. Use the Raise and Lower Keys until the PV display represents the simulated high input.
9. Press the Return Key for at least 6 seconds (maximum 16 seconds), then release. This enters the
high calibration figure into the controller’s non-volatile memory.
10.Turn power off to the unit, remove all test wiring and replace sensor wiring (observing polarity).
3.9
Automatic tuning
The STATOP 4849 controller is equipped with an auto-tuning facility which will set arbitrary control
settings and remove much of the tiresome procedure of manually setting control parameters at plant
start-up. To initialise auto-tuning, use the following procedure :
1. Ensure that controller is correctly configured and installed. If configuration or calibration are not set,
refer to preceding sections.
2. Ensure Proportional Band " Pb " is not set at « 0 ».
3. Ensure process temperature is well (at least 20%) below setpoint. Cold start-ups work best.
4. Press Return Key for at least 6 seconds (maximum 16 seconds). This initialises the Auto-Tune function.
(To abort auto tuning procedure press Return Key and release).
5. The decimal point in lower right corner of display flashes to indicate Auto-Tune is in progress. Auto-
Tune is complete when the flashing stops. Upon completion of Auto-Tune the new P-I-D settings are
automatically entered into the controller’s non-volatile memory.
NOTES :
■
If the " AtEr " display occurs, the automatic tuning process is aborted due to the system operating in
ON-OFF control (Pb = 0). The process will also be aborted if the setpoint is set too close to the
process temperature or if there is insufficient capacity in the system to reach setpoint (e.g. inadequate
heating power available).
■
Please be patient ! Depending on the particular process, automatic tuning may take up to two hours.
Processes with log time lags will take the longest to tune. Remember, while the display point flashes
the controller is auto-tuning.
3.10 Ramp / Soak / Dwell Functions
The STATOP 4849 controller can be configured to act as either a fixed setpoint controller or as a single
ramp controller on power up. This function enables the user to set a predetermined ramp rate to allow the
process to gradually reach setpoint temperature, this producing a " Soft Start " function.
A dwell timer is incorporated within the STATOP 4849 and the alarm relay can be configured to provide
either a dwell function or a soak function to be used in conjunction with the ramp function.
Summary of Contents for Statop 4849
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