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4.8 – REACHING OF THE SET POINT WITH CONTROLLED SPEED AND AUTOMATIC COMMUTATION BETWEEN TWO SET
POINT (RISE RAMP, FALL RAMP AND DWELL TIME)
All the parameters referred to the ramps functioning are contained into the group
“
]
rEG”.
It's possible to reach the set point in a predetermined time (in any case longer than the time the plant would naturally need).
This could be useful in those processes (heating or chemical treatments, etc.) on which the set point has to be reached
gradually, in predetermined times.
Once the instrument has reached the first Set Point (SP1) it’s possible to have the automatic commutation on the second Set
Point (SP2) after a programmed time, obtaining in this way a simple automatic thermic cycle.
These functions are available for all the programmable control types (PID single and double action, ON/OFF and Neutral
Zone ON/OFF).
The functioning is defined by the following parameters :
"SLor"
- Gradient of rise ramp (Process value < Set point) expressed in unit/minute
"SLoF"
- Gradient of fall ramp (Process value > Set point) expressed in unit/minute.
"dur.t"
– Dwell time of Set Point SP1 before the automatic commutation on Set Point 2 SP2 (expressed in min. and sec.)
The functions are deactivated when the relative parameters are = InF.
When the Set Point value is changed or at the switching on, the instrument automatically determines which one of the two
value “SLor” or “SLoF” it has to use.
Note:
In case of PID controller, whether it’s desired to effectuate the autotuning whilst the ramp function is active, this one will
not be executed until the tuning cycle is not finished.
It’s therefore recommended to start the autotuning avoiding to activate the ramp function and, once the tuning is finished, do
deactivate the autotuning (“Auto” = OFF), do program the desired ramps and, if it’s desired the automatic tuning, do enable
the Selftuning function.
Examples : start from values lower than SP and with decreasing of SP.
