Configuration Of Pid Gradient; Pid Valve Configuration; Pid Alarm Configuration - gefran 3850T Use And Installation Manual

4.15.4.5. Configuration of PID Gradient

The gradient page is used to set a gradient on variation of
the PID SetPoint or variation of power.
There are two parameters for gradient on variation of the
SP:
• GRAD INC: SP increase gradient
• GRAD DEC: SP decrease gradient
• GRAD OUT: gradient of the variation in output power,
acting on the variation of delivered power (%) per sec-
ond and active all the time.
If GRAD INC and GRAD DEC are used, the SSP variable will
show the current set point.
GRAD INC and GRAD DEC are expressed in the units of
measurement of the PV / seconds or minutes. The time
base may be set by pressing the appropriate button. GRAD
OUT is expressed as a percentage.
These parameters are only active when PID is set to
automatic, Self Tuning is disabled and there is no active
programmer for the PID in question.

4.15.4.6. PID valve configuration

The Valve page lets you configure valve control. This type
of control is compatible with both regulation in cascade and
regulation as a ratio. The page only opens if Valve mode
was set in the Synoptic page for the PID.
To open the valve page, double-click the Base button and
select Valve from the drop-down menu. The Valve page can
be opened from other pages in the Base section by touch-
ing key 4 on the left.
At the top of the screen is the number of the PID under
examination, which may be changed using the - and +
buttons.
Turn the PID on and off with the EN button. The key turns
80703B_MHW_2850T/3850T_02-2019_ENG
green when the PID is enabled.
The value can be entered with the virtual keyboard by
touching some parameters.
The available parameters are:
• SP: Setpoint, value to be reached and maintained.
• PV: Process value, current value (read only).
• travel time: indicates the time, in seconds, the valve
motor requires to move it from the "fully closed" to
"fully open" position or vice versa.
• Man: touch the key to enable or disable manual regula-
tion. The key turns green when on.
• T_LO: Minimum pulse: expressed as a percentage
(with a resolution of 0.1%) of the actuator time, it
represents the minimum valve position variation cor-
responding to the minimum power variation provided
by the controller (power under which the actuator does
not respond physically to the command).
Increasing T_LO decreases the wear of actuator to the
detriment of positioning precision. The minimum pulse
duration can be set in T_ON as a percentage of the
actuator time. When you set T_LO, the same value is
automatically set in T_ON.
• T_HI: Impulsive tripping threshold: expressed as a per-
centage (with resolution of 0.1%) of the actuator time,
it represents the deviation of position (required posi-
tion - real position) under which the switching request
becomes impulsive.
T_HI is only active with T_OF = 0. The kind of impul-
sive approach allows fine control of the valve position,
which is useful especially in cases of high mechanical
inertia.
• T_ON: is the minimum time of the control valve pulse
expressed as a percentage of the actuator time. You
should set T_ON to the same value as T_LO.
• T_OF: is the minimum time between two valve ON
commands expressed as a percentage of the actuator
time.
Setting T_OF = 0 excludes the function.
Setting T_OF ≠ 0, valve switching becomes impulsive
throughout the position deviation (pulse ON Time = T_
ON and OFF time = T_OF). A value set in T_OF <T_ON
is forced to T_ON.
A bar graph displays the level of valve opening, even in per-
cent. 0% means valve fully open, 100% valve fully closed.
Warning! The valve opening indication is linear, a percent-
age value of the total valve travel time, result of a pure linear
calculation.
The opening reading is real at the travel limits and in the
middle.
In order to have a real information about the phisical posi-
tion of the valve on all the travel, so the real opening for the
fluid flow, a position feedback signal must be used.
Power displays the percent power calculated at that time
by the PID and if used for heating (red LED) or cooling (blue
LED).
Heat/Cool selects the valve operating mode: Heat controls
a heating valve, Cool a cooling valve.
Valves without feedback should e used only if their flight
time is greater than 5 seconds. Under this time, estimate
resolution is worse than 0.5%

4.15.4.7. PID alarm configuration

4. CONFIGURATION
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