Dynamic Set Point (Rise Ramp); Alarm Functioning (Al1) - Eliwell EWTQ 905 Manual

cally stops the cycle in progress.
The values calculated by Auto-tuning are auto-
matically stored in the instrument's memory at
the end of the correct PID parameters tuning.
To activate the SELF-TUNING function proceed
as follows
1) Program and activate the desired Set Point.
2) Program par. "Cont" =Pid.
3) Program par. "Func" according to the process
to be controlled through output 1rEG.
4) Program an output as 2rEG if the instrument
controls a dual-action plant
5) Program par. "SELF" = yES
6) Exit from the parameter programming.
7) Connect the instrument to the controlled
plant.
8) Activate Self-tuning selecting par. "tunE" in
the main menu (or by correctly programming
key F).
When the Self-tuning function is active, the led
AT/ST is permanently lit up and all the PID para-
meters ("Pb", "Int", "dEr", etc.) are no longer
visualized.
To stop the Auto-tuning cycle or deactivate the
Self-tuning function select one of the control
types : "rEG", "OPLO" or "OFF" from the menu
"SEL". If the instrument is switched off during
Auto-tuning or with the Self-tuning function
activated, these functions will remain activated
the next time it is switched on.

DYNAMIC SET POINT (RISE RAMP)

All the parameters referring to the ramps func-
tioning are contained in the group "]rEG".
It is possible to reach the set point in a prede-
termined 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.) where the set point has to be
reached gradually, in a predetermined time.
Once the instrument has reached the first Set
Point (SP1) it is possible to have automatic
switching to the second Set Point (SP2) after a
set time, thus obtaining a simple automatic
thermic cycle.
These functions are available for all the pro-
grammable controls (PID single and double
action, ON/OFF and Neutral Zone ON/OFF).
The function is determined by the following
parameter:
"SLor" - Gradient of rise ramp (Process value <
Set point) expressed in unit/minute.
Note: In case of PID control, if Auto-tuning is
desired whilst the ramp function is active, this
will not be carried out until the tuning cycle has
been completed.
It is therefore recommended that Auto-tuning
be started avoiding activating the ramp function
and, once the tuning is finished, deactivate
Auto-tuning ("Auto" = OFF), program the
desired ramps and, if it automatic tuning is
desired, enable the Self-tuning function.
Examples with starts from values lower than
SP and with decreasing of SP.
PV
[Unit]
SP1
change
SP1 Value
EWTQ 905

ALARM FUNCTIONING (AL1)

The alarm is depending on the process value
(AL1) and before to set his functioning it's nec-
essary to establish to which output the alarm
has to correspond to.
First of all it's necessary to configure, in the
parameters group "]Out", the parameters rela-
tive to the outputs required as alarm ("O1F" ,
"O2F") programming the parameter relative to
the desired output as follows :
= ALno if the alarm output has to be ON when
the alarm is active, while it's OFF when the
alarm is not active
"AL1t" – ALARM TYPE : the alarm output can behave in six different ways.
PV
AL1
OUT
AL1
off
LoAb = ABSOLUTE LOW ALARM: The alarm is
activated when the process value goes below
the alarm threshold set on parameter "AL1".
With this mode is possible to program the mini-
mum and the maximum set of "AL1" by "AL1L"
and "AL1H" parameters.
PV
SP1
-AL1
OUT
AL1
off
LHAb = ABSOLUTE BAND ALARM: The alarm
is activated when the process value goes under
the alarm threshold set on parameter "AL1L" or
goes higher than the alarm threshold set on
parameter "AL1H".
PV
AL1H
AL1L
OUT
AL1
off
HidE = DEVIATION HIGH ALARM: The alarm is
SP1
activated when the process value goes above
the value [SP + AL1]. With this mode is possible
to program the minimum and the maximum set
of "AL1" by "AL1L" and "AL1H" parameters.
time [min.]
HAL1
ON ON
time
off off
LoAb
HAL1
ON ON
time
off off
LodE
HAL1
HAL1
ON ON
time
off off
LHAb
= ALnc if the alarm output has to be ON when
the alarm is not active, while it's OFF when the
alarm is active
= ALni if the alarm output has to be ON when
the alarm is not active, while it is OFF when the
alarm is active but with reverse led indication
(led ON= alarm OFF).
Have now access at the group "]AL1", and pro-
gram on par. "OAL1" , to which output the
alarm signal has to be sent.
The alarm functioning is instead defined by
parameters (see Group "]AL1" (parameters
relative to alarm AL1):
PV
AL1
ON
OUT
AL1
off off
HiAb
HiAb = ABSOLUTE HIGH ALARM: The alarm is
activated when the process value goes higher
than the alarm threshold set on parameter
"AL1". With this mode is possible to program
the minimum and the maximum set of "AL1"
by "AL1L" and "AL1H" parameters.
PV
AL1
SP1
ON
OUT
AL1
off off
HidE
LodE = DEVIATION LOW ALARM: The alarm is
activated when the process value goes below
the value [SP + AL1]. With this mode is possible
to program the minimum and the maximum set
of "AL1" by "AL1L" and "AL1H" parameters.
PV
AL1H
SP1
AL1L
ON ON
OUT
AL1
off off
LHdE
LHdE = DEVIATION BAND ALARM: The alarm
is activated when the process value goes below
the value [SP + AL1L] or goes above than the
value [SP + AL1H]
HAL1
ON
time
off
HAL1
ON
time
off
HAL1
HAL1
time
off
5/8