gefran 2500 User Manual

Auto-Tuning
Enabling the auto-tuning function blocks the PID parameter settings.
It can be one of two types: permanent (continuous) or single-action (one-shot).
* Continuous auto-tuning is activated via the Stu parameter (values 1, 3, 5). It continuously reads system
oscillations, immediately seeking the PID parameter values that reduce the current oscillation. It does not
engage if the oscillations drop below 1.0% of the proportional band.
It is interrupted if the set-point is changed, and automatically resumes with a constant set-point. The calculated
parameters are not saved if the instrument is switched off, if the instrument is switched to manual, or if the
configuration code is disabled. The controller resumes with the parameters programmed before auto-tuning
was enabled.
The calculated parameters are saved when the function is enabled from the digital input or from the A/M
(start/stop) key if the procedure is interrupted.
* One-shot auto-tuning can be enabled manually or automatically. It is activated via the Stu parameter (as can
be
seen on the table, the values to be set depend on whether Self-tuning or Soft-start is enabled.).
It is useful for calculation of PID parameters when the system is around the set-point. It produces a variation on
the control output at a maximum of ± 100% of the current control power limited by h.PH - h.PL (hot), c.PH -
c.PL (cold), and assesses the effects in timed overshoot. The calculated parameters are saved.
Manual activation (Stu code = 8, 10, 12) via direct setting of the parameter or via digital input or via key.
Automatic activation (Stu code = 24, 26, 28 with error band of 0.5%) when the PV-SP error exceeds the
preset band (programmable to 0.5%, 1%, 2%, 4% of full scale).
NB: at power-up, or after a change of set-point, automatic activation is inhibited for a time equal to five times the
integral time, with a minimum of 5 minutes.
The same time has to run after one-shot.
One-shot auto-tuning is not active for PVs lower than 5% and higher than 95% of scale.
Controls
Control output with proportional action only if propor-
tional heating band overlaps proportional cooling band.
PV = process value
SP = heating setpoint
SP+cSP = cooling setpoint
Control output with proportional action only if propor-
tional heating band overlaps proportional cooling band.
h_Pb = proportional heating band
c_Pb = proportional cooling band
time
PV
c_Pb
h_Pb
SP+cSP
SP
+100%
Control output
0%
-100%
time
PV
c_Pb
h_Pb
SP+cSP
SP
+100%
Control output
0%
-100%
Heating/Cooling control with relative gain
In this control mode (enabled with Ctr = 14 parameter) the type of cooling has to be specified.
Cooling PID parameters are therefore calculated based on heating parameters according to the specified ratio.
(for example: C.ME = 1 (oil), H_Pb = 10, H_dt = 1, H_It = 4 implies: C_Pb = 12,5, C_dt = 1, C_It = 4)
We advise you to apply the following values when setting output cycle times:
Air T Cool Cycle = 10 sec.
Oil T Cool Cycle = 4 sec.
Water T Cool Cycle = 2 sec.
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gefran 2500 Specifications

General

Brand	gefran
Model	2500
Category	Controller
Language	English